The future of interventional cardiology

Academic journals devoted to the field of interventional cardiology have become an unmatched source of information over the last decade or so, keeping us up-to-date with the latest developments and broadening our horizons as interventional cardiologists. As we celebrate the arrival of a new peer-reviewed journal in interventional cardiology, REC: Interventional Cardiology,1 we take the opportunity to reflect on recent developments in cardiology and contemplate the future direction of this dynamic and diverse specialty.

The development of coronary catheterisation by Sones in 1958, followed by the introduction of dedicated coronary catheters by Judkins and Amplatz in 1967, and ultimately, the introduction of percutaneous coronary intervention (PCI) by Grüntzig in 1977 established interventional cardiology as a subspecialty of general cardiology.2 The first coronary stenting procedures conducted by Sigwart and Paul in 1986 and the subsequent development of drug-eluting stents with succeeding iterations, along with other advances in device technologies, transcatheter techniques, and adjunctive pharmacotherapies, have facilitated treatment of more and more complex patients- and lesion-subsets with PCI. Coincidentally, the development of percutaneous interventions for the management of structural heart disease resulted in the emergence of a new subspecialty of cardiac transcatheter interventions: structural intervention. The inception of transcatheter aortic valve implantation (TAVI) by Cribier in 2002 revolutionised the treatment of aortic stenosis.3 More recently, transcatheter edge-to-edge mitral valve repair has been shown to be beneficial for moderate-to-severe or severe structural or secondary mitral valve regurgitation.4^,5 Such advances have arguably resulted in structural intervention becoming the fastest growing subspecialty within the field of cardiology. The introduction of the electrophysiology study into clinical practice in the late 1960s, followed by the development of catheter ablation (initially through the delivery of high energy shocks to interrupt conduction, and later using radiofrequency current, the latter pioneered by Budde, Breithardt and Borggrefe) resulted in the widespread adoption of transcatheter therapies for the management of cardiac arrhythmias.6 In summary, the field of cardiac transcatheter interventions now includes three distinct subspecialties: coronary intervention, structural intervention, and catheter ablation.

The setting-up of subspecialties of transcatheter intervention is certainly beneficial to patients. It increases the availability of state-of-the-art cardiac care provided by highly-skilled physicians and allows the treatment of high-risk patients who would have previously been managed conservatively. Indeed, it has been shown that the management of patients by the relevant cardiology subspecialist reduces the length of hospital stay, cardiac readmissions, and mortality.7

However, the division of cardiology into niche subspecialties also has potential negative implications for patients and cardiologists alike. With respect to patients, highly subspecialised cardiologists may tend to be more focused on the condition or intervention at hand than on the patient as a whole. However, in our increasingly elderly cardiac patients, such conditions rarely occur in isolation: coronary artery disease, valvular heart disease, and cardiac arrhythmias frequently coexist. In addition, a cardiologist performing an intervention may not see the patient again before discharge and the success of the catheterization may be a distraction from the need to optimize other issues related to medical management, such as intensifying preventive therapies or optimising heart failure or antianginal medication. For both referring physicians and patients, the division of cardiology adds a degree of complexity to the referral process. It may be difficult for the referring physician to decide at the time of the referral what cardiology subspecialist will most appropriately manage the patient’s ailment.

Finally, for cardiologists, subspecialisation has resulted in more difficult training. Is it appropriate for trainees to start to perform catheter ablations before completing their basic cardiology training? Is it advisable that trainees start their training in structural intervention before being competent in performing coronary interventions? Either situation would seem ill-advised but the trade-off is longer training that adds to an already onerous training path in general cardiology.

There is also a risk of isolation from cardiology colleagues in other subspecialties. Ironically, at a time when both European and American guidelines for clinical practice recommend a multidisciplinary or “heart team” approach to the management of patients with valvular heart disease8^,9 bringing together interventional cardiologists, cardiac surgeons, cardiac imaging specialists, and anesthesiologists, the specialty of cardiology has never been so divided. Structural interventional cardiologists now frequently work more closely with cardiac surgeons than with other cardiologists. Whereas, in the past, ward rounds on the cardiology ward often included cardiologists from numerous subspecialties covering all aspects of cardiac care, nowadays, in many centres, interventional cardiac subspecialties work independently from general cardiology or other subspecialties. We are beginning to reach a point where it can be difficult to set up a heart team with our own cardiology colleagues.

Whom does such a structure serve? Subspecialisation is defined by the operator and his expertise. Arguably such a structure is more physician- than patient-oriented, with each subspecialty managing one condition rather than the patient as a whole. However, we should not lose sight of the big picture. Our management goals should be patient-centred rather than diagnosis- or procedure-centred. In patients requiring multiple interventions from different subspecialties, decisions on the appropriate order of such interventions should be made collectively with our colleagues and not in isolation. As we continue to treat older, more complex patients with a heavier co-morbidity burden, co-operation between cardiology (and non-cardiology) subspecialties will become more important than ever.

In summary, while the arrival of highly-specialised cardiologists should be welcome, the side-effect of the division of cardiology should be avoided. United as cardiologists, we are in a stronger position to provide better care for our patients, exchange ideas, learn from one another, and collaborate on projects. We need to learn to have the courage to call ourselves cardiologists rather than let our subspecialties define us. Otherwise, if the current trend continues, future clinical practice guidelines in cardiology will need to advocate for a multidisciplinary approach between cardiology subspecialties in patient-care, while the current recommendations for a heart team approach between medical and surgical disciplines will take lower priority.

CONFLICTS OF INTEREST

The authors declare no conflicts of interest.

REFERENCES

Instead of writing a conventional editorial I have tried to respond to the question of Dr Fernando Alfonso, Associate Editor of REC: Interventional Cardiology: “where are we going?” by letting myself be interviewed by a senior interventional cardiologist from South America, Dr Rodrigo Modolo, who is currently writing his PhD thesis in Rotterdam.

QUESTION: Professor, do we need another interventional cardiology journal?

ANSWER: Rodrigo, in the United States we have, ranked by their impact factors, 3 influential interventional cardiology journals: JACC: Cardiovascular Interventions, Circulation: Cardiovascular Interventions, and Catheterization and Cardiovascular Interventions.

In Europe, EuroIntervention is the journal of the EAPCI (European Association of Percutaneous Intervention). But we have a tendency to forget that the language of the South American continent is Spanish (…and Portuguese, as Dr Modolo reminded me), and the Spanish language represents one of the 3 most widely spoken languages in the world.

Revista Española de Cardiología currently has a major impact factor and faces the challenge of creating a new subspecialty journal, REC: Interventional Cardiology. It is a challenging decision but also a great opportunity.

Q.: Do you think that interventional cardiology has reached its peak maturity?

A.: Interventional cardiology has reached the peak of its 40 years of existence and it is difficult to predict the future. The advent and adoption of balloon angioplasty with an initial success rate of 80% to 85% and a restenosis rate of 30% will not happen again, nowadays. Bare-metal stents and drug-eluting stents were and are successful stories, but, purely as examples, directional atherectomy and laser for the treatment of coronary artery disease did not survive rigorous randomized controlled trials.1^,2

Q.: Prof. following Andreas Grüntzig, has there been in your view another major pioneer in the field?

A.: After Andreas Grüntzig, the second great pioneer was Alain Cribier, who has revolutionized the field of valvular treatment. Over the last decade, interventional cardiologists have systematically “copied the technical approach, tips and tricks of the surgeons” (eg, the Alfieri edge-to-edge clip technique for mitral repair)–and will keep doing so (figure 1).3 The 20th and the early 21st century have been and will be the centuries of implantable devices (starting with the pacemaker implanted by Åke Senning, a surgeon and pioneer). Today, “drugs and surgeon” seem to be being supplanted by permanently implanted devices, due to their benefits, cost-effectiveness, and other advantages.

Figure 1. Different approaches for mitral valve interventions. Reprinted from Taramasso et. al.,3 with permission from Europa Digital & Publishing. LV, left ventricular; TMVI, transmitral valve implantation.

However, we have attempted and we keep trying to replace permanent metallic implants by a bioresorbable template to facilitate a vascular or valvular restoration therapy with cellular colonization of the template. So far we have not convinced the interventional community.4,5 But a first attempt with a novelty in interventional cardiology is frequently imperfect, facing new enemies and sometimes it is doomed to disappear.

Q.: Fernando Alfonso asked you the question: “where are we going?” Could you provide him with your personal response?

A.: How could I possibly answer the question? I will try, but let me tell you that the history of interventional cardiology has so far been unpredictable and intimately related to the history of medicine, biology, physics, and other disciplines.

Q.: Why does interventional cardiology have to be related and connected to the world of molecular biology, biomechanics, epidemiology, physics, etc?

A.: Let me answer your question by telling you my recent perception of progress in medicine at a meeting in December 2018, at the Cardiovascular Symposium of Valentín Fuster in New York. In the last session I was a speaker, sandwiched between 2 giants in medicine: Eugene Braunwald and Alain Carpentier, the surgeon who revolutionized the treatment of the mitral valve. It gave me the opportunity to dialogue with the generation that preceded my generation and to ask them (it’s my turn) the question “where are we going?”

Dr Braunwald gave a very clear and succinct answer. Number 1, the use of genomics for the early detection and prevention of disease will fully emerge in the next decades. Number 2, the predominance of noninvasive imaging (multislice computed tomography scans, positron emission tomography, magnetic resonance imaging, and a combination of these imaging techniques) will be predominant and replace conventional diagnostic cinefluoroscopy as well as many other diagnostic tests. In our weekly research discussion and as a joke, the fellows and myself frequently evoke the “Imagomics” era (a combination of imaging and genomics). Number 3, the discovery of new biomolecules and physiological principles such as PCSK9 blockers (not only monoclonal antibodies against PCSK9 but microRNA inhibitors of PCSK9 production) and others such as iSGLT2, which inhibits sodium-glucose pump reabsorption in the kidney while differently affecting the afferent and efferent vessel of the kidney glomeruli, a drug that might have major effects not only on diabetes, but also on heart failure and proteinuria. With child-like enthusiasm Dr Braunwald described that drug as the “statin of heart failure”.

When he was asked about the relationship with percutaneous intervention his response was swift. The Fourier study on monoclonal antibodies against PCSK9 has already demonstrated a 22% reduction in coronary interventions, warning us, interventional cardiologists, that a drastic change in the treatment of stable angina may be on the horizon in the next decade.6

Early detection by genomics of coronary artery disease risk factors, early demonstration by noninvasive imaging of the subclinical phenotype of the disease and early treatment by biannual injection of microRNA to block the production of PCSK may potentially “eradicate” the disease as predicted by the 2 Nobel prize laureates for their discovery of low-density lipoprotein receptors, Michael Stuart Brown and Joseph L. Goldstein in 1985 in their inaugural lecture in Stockholm.7 He added that so far there is no real device treatment for heart failure, a complex multifactorial disease, although resynchronization and mechanical bipartition of the dyskinetic aneurysmal left ventricle are partially successful.8 As far as diabetes is concerned, a late key opinion leader in interventional cardiology did benefit from an implanted insulin micropump but beyond that device there is no specific device for the “causal” treatment of diabetes (such as renal denervation) and we still have to depend on pancreas transplantation.9

For his part, Alain Carpentier has for many years been focusing on the intrathoracic artificial heart as a final mechanical treatment of heart failure. His artificial heart CARMAT (Carpentier and Matra Company) is a marvel of technology, and has been implanted in 14 patients. These 2 giants, Braunwald and Carpentier, have obviously opposite but complementary views on the topic of heart failure.

Valentín Fuster, our host at this meeting in New York, relies strongly on primordial prevention (prevention in children between 3 and 5 years), primary and secondary prevention in an attempt to alleviate the burden of coronary artery disease in the decade to come.10 More modestly, at that meeting I reviewed our work on tailor-made decision-making between percutaneous coronary intervention and coronary artery bypass graft based solely on non- invasive imaging.11-14 Clearly one of my predictions is the disappearance of diagnostic cinefluoroscopy from conventional catheterization laboratories, which in future will have to be used exclusively in an interventional suite.11-14

After SYNTAX III, the Revolution CABG trial–on the verge of starting–on the planning and execution of surgery without prior cineangiography, thus guided solely by multislice computed tomography, will be an important first-in-man trial and a proof-of-concept.

Q.: Then, what about the “unpredictability” of the evolution of interventional cardiology?

A.: Dr Modolo, let me illustrate that unpredictability by the following anecdotes. In 1974, in Frankfurt, at a meeting organized by Paul Lichten and as a young catheterization laboratory physician, I went to see the poster of a young radiologist called Andreas Grüntzig. Honestly I could not anticipate that his technique, called percutaneous transluminal balloon angioplasty, applied on a dog’s left anterior descending coronary artery ligated by a piece of catgut, would ever mark the beginning of a new clinical era just 1 year later.15

In 1986 when I tried to follow and to apply the pioneering endeavor of Jacques Puel and Ulrich Sigwart with the Wallstent, I could not anticipate that I would report in the New England Journal of Medicine in 1991 a rate of acute or chronic occlusion above 20%!16

It took me 3 years to recover from this disastrous publication; in 1994 in the New England Journal of Medicine the results of the Benestent trial17 with the balloon expandable Palmaz-Schatz were embraced swiftly by the interventional community.

I must admit that in 1999 I immediately saw the tremendous potential of rapamycin (sirolimus drug-eluting stent) when I was exposed to the experimental animal work of Robert Falotico at the headquarters of Cordis in New Jersey.18

In 2002, I implemented a policy of unrestricted use of drug-eluting stents fiercely criticized at that time, but today fully endorsed by the interventional community.19

In 2004, Alain Cribier helped me to perform our first antegrade valve replacement at the ThoraxCenter; but it took me another year to start the CoreValve program in collaboration and competition with Eberhard Grube. In both institutions, initial cases were performed either with extracorporeal membrane oxygenation or TandemHearts. These historical anecdotes show that I was not and am still not a visionary pioneer but just a fast adopter, and that the future of interventional cardiology is quite unpredictable; Rodrigo, as another example, the surge, demise and the rebirth of renal denervation. So, do not ask me to be precise in futuristic prediction.

Q.: Thus you will not answer the question of Dr. Alfonso, where are we going?

A.: I will try to answer this question but the prediction would have to be checked over the next decade.

This decade is ending with a “war on stents”. All the clinical outcomes of the novel stents are in the range of 5% for target vessel failure (table 1), but 1 patient in 5 has residual angina.20 That has to be elucidated by sophisticated physiology that has to identify the epicardial stenotic lesion to be treated, for significant physiological reasons, the epicardial angiographic stenosis that should not be treated, and the presence of diseased microcirculation.21 We will have to resolve the concordance and discordance between fractional flow reserve and coronary flow reserve and find a biological treatment for the microvascular disease. Noninvasive imaging is also emerging to make the triage between the lesion that needs to be treated and those that have to be left alone (figure 2).

Table 1. Primary outcomes of recent stent trials

Figure 2. Introduction and evolution of coronary physiology in the clinical laboratory. CFD, computational flow dynamics; FFR_CT, fractional flow reserve in cardiac tomography; SFR, stenotic flow reserve.

In figure 2 I summarize the introduction and the evolution, which I have witnessed, of physiology in the clinical lab starting with the Young equation in 1975 and ending up with the quantitative flow ratio. I would not be surprised if I see a return of the so called “Vogel technique”,22 which combines the appearance time of the contrast medium in the epicardial vessel during conventional angiography and the videodensitometric assessment of the myocardial blush to assess the coronary flow reserve from cineangiography. Combined with the quantitative flow ratio, it may again become an appealing technology not requiring the use of the pressure wire, and providing the clinician with fractional flow reserve and coronary flow reserve simultaneously.

It is superfluous to describe the extraordinary explosion of structural heart treatment. Just to put history and prediction into perspective, in a keynote lecture at EuroPCR in May of 2007, I reviewed the outcomes of 677 patients with aortic stenosis treated worldwide with transcatheter aortic valve implantation. At that time, the ThoraxCenter had treated 61 patients (nearly 10% of the worldwide population with transcatheter aortic valve implantation!). Today, all 4 valves (with stenosis or regurgitation) have been treated and hundreds of thousands of patients have been treated. I have already mentioned in this interview the concept of restorative therapy aiming to replace the animal bioprosthesis fixed in glutaraldehyde. Certainly another decade will be necessary to achieve that goal. Alain Carpentier wants to put an end to the “cannibal activity” of heart transplantation.

Q.: Will interventional cardiology expand in other noncardiologic fields?

A.: In the next decade, the field of ischemic stroke treatment will have to be conquered more aggressively and become a successful story like “stent for life”. As pointed out by Petr Widimsky in a recent editorial in EuroIntervention,23 the bar for training in neurointervention for interventional cardiologists has maybe been set too high by neurointerventionists in their attempt to collaborate with interventional cardiologists. Fusion of specialized knowledge –neurointervention–and long battlefield practice of interventional cardiologists in revascularization of myocardial infarction has to be accomplished in the next decade.

Artificial intelligence, learning machines, and big data are today common in our scientific discussions. However my personal experience is that you need a specific target. With Imperial College, we are currently focusing on a fully automatic anatomic SYNTAX score derived from multislice computed tomography (segmentation, tortuosity, length of lesion, identification of long diffuse lesion, metric evaluation of calcium… all can be mastered by the so called artificial intelligence) (figure 3).

Figure 3. Automatic segmentation of the coronary tree derived from multislice computed tomography showing an accuracy of 97%.

Finally, big data has become a reality. Just a few weeks ago on all European TV screens we saw the first results obtained from 8 million data collected on implants, thereby detecting unusual and rare complications otherwise not reported by industries or physicians.

Finally, 2 very important clinical fields, as I mentioned earlier, diabetes and heart failure remain outside and beyond our device approach (so far…). In the previous decade, there was the tremendous hype that myogenesis would be a fast solution to this endemic cardiovascular entity.24 Bipartition of the dyskinetic aneurysmatic ventricle is only a very specific approach, close to a niche, and on the horizon there is at this point of time nothing very promising. Basic science will have to make major discoveries before we, interventional cardiologists, get seriously involved in the field of myocardial repair. But as usual we will be surprised by the ingen-iousness of the human mind. To end on an optimistic note, renal denervation almost died a few years ago as a consequence of rig-orously controlled trials with sham,25^,26 but this year there was clearly a rebirth or renaissance of renal denervation with 2 new positive trials using a sham arm as a comparator.27^,28

In the next decade, the wealth of knowledge stemming from the use of genomics, big data, and artificial intelligence will deeply affect our lives as human beings, physicians, and interventional cardiologists. More than ever, the new journal will have to guide us through the enormous flow of information.

CONFLICTS OF INTEREST

The authors declare no conflict of interest for the present editorial.

REFERENCES

Before speculating on where interventional cardiology is heading to, it may be helpful to reflect on its true origin. For many of you, early or halfway through your career, interventional cardiology may seem a well-established and mature subspecialty. For you it has always been a major component within the field of cardiology. However, for those of us who were already here before interventional cardiology even existed and have witnessed its birth, child- hood, and adolescence, interventional cardiology is just a moment in time. Currently, we feel pretty confident that we are treating coronary artery disease adequately with prompt interventions for the management of acute myocardial infarctions and chronic conditions with sophisticated instruments, excellent results, and satisfied patients. We also felt confident when we had balloons only. Yes, there were many failures back then, but interventional cardiology would have never flourished if it was not for optimism. I keep a video recording of our colleague and father of interventional cardiology, Andreas Gruentzig, MD, just before his untimely death. He said that balloons were the solution for many conditions, but also that we needed much more than that if we wanted to solve the obvious problems of coronary artery obstruction. The next decade would witness innovation attempts, some of them ranging from excellence to eccentricity1 All types of lasers to burn, seal, selectively ablate only abnormal tissue; hot-tip catheters; cold freezing instruments; cutters and scrapers; and finally scaffolds that we would call stents. Peripheral artery interventions followed a similar path. Although these came before coronary interventions, these techniques evolved slower. The ability to perform minimally invasive procedures for structural heart disease lagged behind. In the late 1980s, Alain Cribier, MD presented the idea of balloon dilatation of the aortic valve at our Emory courses2 We tried it for some time. Fifteen years later he implanted the first transcatheter aortic valve. It takes a while before ideas come to life. Back in 1990, we predicted that restenosis would be conquered by a device to hold the artery open combined with locally-delivered anti-proliferative agents. At first, we tried radiation, but cell-cycle inhibition stents eventually became the standard of care.

There were many difficulties then. Some were overcome, and some carried their own issues. What are the problems we face today, and how will they be approached in the future? The most successful coronary intervention occurs in the setting of acute myocardial infarctions. Making this technology widely available is still challenging because even though it can be done, myocardial salvage has not been completely solved. Innovations such as left ventricular support combined with reperfusion while paying special attention to microcirculation and its response to reperfusion deserve further research. We still do not know what to do with non-culprit but narrowed coronary arteries in the setting of myocardial infarctions.

Techniques for opening chronic total occlusions and bifurcation lesions have progressed, but we still don’t have dedicated devices for bifurcations, and reopening chronic total occlusions through the true lumen requires innovations that are still to come. Although percutaneous aortic valve implantation has evolved faster than any of us would have anticipated, long-term results are still awaited, and mitral and tricuspid valve replacements are still in their infancy. Peripheral endovascular therapies seem spectacular, but endo-leaks and aneurysm expansion have not been completely solved yet.

Also, the lines between disciplines are blurry. Stroke intervention is the most dramatic advance in the field. Will clot retrieval from cerebral arteries remain the scope of neurologists only? There are not enough of them, and cardiologists are entering their specialty. On the other hand, interventional cardiology will not be the sole domain of cardiologists. A recent approach to the excessive stroke rate from carotid stenting has resulted in the direct surgical exposure of the artery with stent implantation combined with reverse carotid blood flow enabled by a shunt via the femoral vein. This kind of innovations combine surgical skills and training together with catheter skills. An interdisciplinary collaboration that can be perfected in some healthcare systems. A trial sponsored by the National Heart, Lung, and Blood Institute (NHLBI) is now underway to assess the validity of a hybrid approach for the management of coronary revascularization, ie left internal mammary artery to the left anterior descending artery through minimally invasive techniques combined with drug-eluting stents for the management of other lesions.3

The problem of cardiovascular disease will not be solved with devices alone. Recognizing the progression of atherosclerosis not only in non-stented segments but also inside the stents will turn interventional cardiologists into preventive cardiologists. The dramatic breakthroughs in the management of lipids and the cardiovascular effects of new drugs for the management of diabetes means that interventional cardiologists must be competent in these fields as well, since these therapies may become the most relevant “devices” in the future. A total paradigm shift may be underway in the management of stable ischemic heart disease. Diagnosis is now moving away from ischemia detection only to non-invasive coronary imaging in the assessment of physiology and anatomy. Right now the U.S. is behind other countries when it comes to the implementation of CT angiography, but I predict it will become the diagnostic catheterization laboratory of the future. Ad hoc percutaneous coronary interventions during invasive catheterizations may have been acceptable so far, but now with the ability to define coronary obstructions and their physiological significance non-invasively, we can better plan medical therapy, percutaneous coronary interventions, or surgery. Unlike ad hoc percutaneous revascularizations during invasive catheterizations, this will allow true informed consents and facilitate proper diagnoses in patients who may not have agreed previously to an invasive diagnostic procedure.4

It will not reduce the number of interventions but it will certainly guarantee that only the correct ones are performed. A critical consideration for this subspecialty is what the training should look like in this rapidly changing field. Not everyone will be an expert in every aspect, which is why training and continuing medical education will create the expertise required.

The future is always unpredictabe but if the past teaches us anything is that the field of interventional cardiology has a challenging and rewarding future. It is a new field of expertise where there is still much to be done. The launch of this new journal will give you the opportunity to disseminate new knowledge that will shape the future. As my term as editor of JACC: Cardiovascular Interventions was coming to an end I wrote an editorial that was published both in our journal and EuroIntervention5 I called it “The golden age of publishing in interventional cardiology”. Well, that age has not passed yet. I believe that the ability to publish good papers in quality journals has stimulated young investigators to do what needs to be done. This journal will be unique because it will be published in both English and Spanish. I hope that those who feel more comfortable using Spanish will be stimulated not only to read about the advances made on interventional cardiology, but also to contribute to its progress with more publications of their own research. This journal should be popular not only in Spain but throughout the Spanish-speaking countries in the Americas. Congratulations and best wishes to the editors of REC: Interventional Cardiology for this important contribution to our field.

CONFLICTS OF INTEREST

None declared.

REFERENCES

Access to medical literature has seen dramatic changes over the last few years. In less than two decades it has gone from a paperbased system to an online digital sending system. The advances made on computing and, above all, the Internet has revolutionized not only the way manuscripts are sent, but also how fast these get to the public (including reference manager software adaptable to the different format of various journals). This revolution has also touched the way information is being accessed these days. The databases generated at the beginning of the 21st century are «prehistoric» compared to the ones we use today. The digitalization of clinical histories and the creation of software for data mining purposes have accelerated exponentially the preparation and analysis of the data included in the studies. Even researchers have a much more transversal training and it is common to see research teams that are savvy in statistics and that facilitate data analysis. However, all these important changes are nothing compared to the actual access to general medical information. Even though access to medical literature is not actually open (something we will refer to later), access to a great deal of information is just huge. And all this has resulted in an exponential increase in the amount of papers that scientific journals receive on a monthly basis. Also, this is accentuated by the growing productivity of emerging countries or powers, such as China, that has noticeably multiplied the number of scientific papers published over the last few years. As an example, one of the leading journals in the field of cardiovascular disease, the Journal of the American College of Cardiology (JACC), received some 4000 manuscripts every year (3200 original papers/reviews) in a five-year span of time ever since the Spaniard Valentín Fuster took over as editor-in-chief back in 2014. Due to the acceleration in the generation of knowledge and how technical different subspecialties have become, the audience of cardiology journals is particularly interested in certain areas. The large volume and ongoing specialization of the manuscripts being sent to journals, added to the limited number of monthly publications lead to reduced success rates, since quality interesting papers for the cardiological community end up being rejected. Following the JACC example, the acceptance rate of original papers/reviews in the aforementioned span of time was barely 9%. These circumstances have resulted in the creation of sister journals of major journals such as those specialized in interventionism, imaging, heart failure, or arrhythmias, among others. It is expected that this increase in the number of manuscripts submitted to journals will go on and with it, the number of cardiology and subspecialty journals. This growth not only does not dilute the relevance of these journals, but it also promotes medical science while increasing access to knowledge and how this knowledge is spread. A common practice of high-impact journals for high-quality papers that are considered highly specialized is to offer the authors the re-submission of the manuscript to sister journals. In the aforementioned years, around 4% of the original papers/reviews published by the JACC were re-submitted and ultimately accepted by JACC: Cardiovascular Interventions. This practice accelerates the process of publication and guides authors on the possible interest of the journal at hand.

It is a paradox that, with all the digitalization we have seen so far, the main scientific journals, particularly the cardiology ones, still have the classic format of a paper journal with a limited number of papers being published each year. We believe that the actual global tendency will put this format to rest any time soon. It was with this idea in mind that the digital format open access journals were born. But yet despite its appeal, its impact is nowhere close to that of classical journals, which opens the debate on what readers and authors of journal manuscripts are really looking for. In a general sense, readers want to have access to information to know about the advances being made and be briefed on a particular theme. On many occasions, the reader cannot evaluate whether the studies published have been done correctly, or whether the existing literature on a particular issue has been reviewed appropriately. That is why the reader is in a quest for «leading» journals with a quality seal that will guarantee that the material being published has passed all the filters and has, therefore, been appropriately arranged and exposed for the public. In this sense, the role of editors is just essential since, in a way, they bring their own imprint to the journal. There are several quality seals for the assessment of journals, among them, the impact factor (IF) is the most popular one to assess the impact a journal has made among its audience. The IF is an annual «official» estimate - it is the measure between the citations received during a year to the articles published in a journal over the two previous years and the number of articles published during the same period. The higher the IF the higher the quality of a journal. The IF is estimated annually by a private company (Clarivate Analytics) that establishes the ranking of journals within their field of expertise. There are other metrics for the assessment of the impact journals make (Google Scholar¹ is becoming more and more popular these days) but, as it occurs with the IF, these metrics are imperfect and do not make assessments of all the quality aspects included in a scientific journal. As the JACC editor-in-chief says in an editorial from 2017², the IF is a curious fanciful metrics, since the presence of a highly cited paper (clinical guidelines would be the most significant example here) plays a very important role in the journal overall IF, even if the remaining papers do not draw much attention. On the other hand, the author of a paper wants to be published in a journal that will give his or her study the highest visibility possible for all the professional implications this brings to the author. Again, the IF plays a very important role when it comes to deciding what journal a paper should be sent to for evaluation purposes. Also, scientists are always looking for national and international funding for their studies, and most assessment agencies measure CVs based on the number and quality of the publications included, which is estimated by the IF and its position relative to other journals in the field. There is, therefore, some sort of vicious circle where readers and authors alike end up looking for the same journals, and it is these journals that will eventually choose, first hand, the most relevant papers, which will, in turn, guarantee good citation levels, high IFs and, eventually, the audience’s interest. Although this system has been highly criticized, there are so many factors orbiting around metrics, that it is hard to imagine a future where readers and authors will abandon these parameters.

A very relevant issue for the editorial committee of a scientific journal is to know what the target audience looks like and, especially, what type of information will be transmitted to them. On this regard, journals can be purely scientific (with predominant original papers) or educational (with predominant reviews on issues of high clinical interest). Journals usually go for some sort of mixed format between the two. However, some purely educational journals have ended up having very high IFs in the field of cardiology such as Nature Reviews Cardiology, that back in 2017 was positioned among the top spots in its field of expertise.

Over the last few years, the Internet revolution has resulted in the creation and vertical growth of social networks that have become a significant ingredient to spread the papers that are being published in scientific journals³. Social networks are essential when it comes to spreading research not only among scientists and doctors, but also among the general public, thus contributing to promote health. This aspect of information spread to non-medical audiences is critical and has become more and more relevant through the years. Recently created metrics such as the Almetric scores measure the impact of journals based on the activity they generate in the social media⁴. A study conducted on the Altmetric scores of the four most relevant cardiology journals revealed some interesting data⁵: a) the Altmetric scores from cardiology journals are usually very high; b) over half of the most popular papers were not original papers but editorials, points of view, clinical practice guidelines, and consensus documents; c) the papers with the highest impact based on this metric were those based on nutrition and lifestyles; and d) open access papers did not have a higher impact compared to pay per read papers.⁵.

One final relevant controversial issue is the cost associated with the publication of a paper and the access to this paper. Several journals -certainly those with the highest IFs of all- usually sign exclusivity deals with major publishing houses that will be formatting, publishing, and editing the papers. In order to have access to complete papers, universities, research centers and even individual professionals pay a subscription fee. This pay per read system certainly limits the spread of knowledge. Several authors decide to pay a fee when their paper has been accepted by a journal so that it is open access, and anybody can have access to it without having to pay a subscription. This fee -usually between 2500€ and 4500€- is already included in the public funding received by the authors. The journals send the manuscript to external unpaid reviewers who are only moved by responsibility and altruism. Therefore, we face a complex situation where the creator of the paper -the author-, the evaluator -the external reviewer and, on many occasions, the editorial committee- and the end user -the reader- pay for the journal in such a way that the economic benefits only go to the distributor of the material -the publishing house- that has only participated in the editing and distribution stages. The fact that studies conducted with public funds are not open access and, therefore, cannot be read by the community and the public, is highly questionable. That is why in some European countries like Sweden they have decided to cancel all subscriptions with big publishing houses in an attempt to push forward the open access to science⁶.

In sum, at the present time, medical journals are undergoing major changes, mainly due to the advance of the Internet and the social media. The future of this road is hard to predict but it seems that journals will end up being completely digital and will go open access for the readers, and with quality seals different than the classical IFs. Due to the huge amount of information available, the creation of subspecialty journals is a tendency that will become more and more popular in order to update professionals on their specific fields of expertise. REC: Interventional Cardiology already possesses many of these future traits. For this reason, we strongly believe the future looks bright ahead thanks to its excellent editorial team and parenting from Revista Española de Cardiología.

Conflicts of interest

The authors declare no conflicts of interest whatsoever.