Most healthcare workers think of interventional cardiology as a well-established medical specialty. However, it would be good to reflect on its true origin because for those who were already part of it even before our specialty was born, the present time is just another step in the timeline of interventional cardiology.

Origins

Today, interventional cardiology has reached its peak after 40 years in the making. I would say that the revolution of this medical specialty started with the arrival of therapeutic procedures. There is no doubt that the pioneer of this specialty was Dr. Andreas Grüntizg, who surprised the entire world with the very first coronary angioplasty. However, it was Dr. Alain Cribier the genius who revolutionized the field of valvular therapeutics. Dr. Cribier taught us how to treat aortic stenosis dilating the valve with a specially designed balloon. But let’s focus on vascular diseases leaving other valvular conditions and structural problems of cardiology for some other time.

Some of the anecdotes that already out there are not well-known. For example, in 1974 in Frankfurt, in a congress held by Dr. Paul Lichten, a young radiologist called Dr. Andreas Grüntzig presented a poster on a brand-new technique called percutaneous transluminal angioplasty used in a dog’s left anterior descending coronary artery. This would mark the beginning of a new clinical era just a year later.1 In 1977, Dr. Grüntzig performed the very first angioplasty in a human being.

But even Dr. Andreas Grüntzig, who said that balloons were the solution to many heart conditions, also used to say that we would need much more if we really wanted to solve the problems posed by coronary obstruction. Dr. Grüntzig developed this technique in Switzerland. Afterwards, he moved to Emory, Atlanta, United States to work with Dr. Spencer King. Unfortunately, shortly after he started living in the United States, he died in a plane crash.

The next decade would witness the birth of multiple innovations, excellent some of them, others somehow weird to say the least. All sorts of lasers to burn, seal or perform selective ablations, hot-tip catheters, cooling devices and scrappers, and scaffolds we would eventually call stents.2 The word “stent” came from a “dentist” who used some type of scaffold in his oral treatments. He used to call that scaffold stent. There is no translation for stent into Spanish. However, stents were the new hallmark to treat coronary obstructions treated with angioplasty. This new metal structure called stent met the requirement of placing a scaffold inside the artery to prevent “the walls from crumbling down”. The Argentinian pioneer who started using stents for the first time was Dr. Julio Palmaz. He was a radiologist who had studied at La Plata School of Medicine, Buenos Aires, Argentina. Afterwards, he moved to the United States where he lives today. It was in the United States were here designed his stent back in 1987. The stent was designed to treat peripheral arterial diseases, especially of the lower limbs. His predecessor in the management of peripheral arterial diseases was Dr. Charles Dotter, a.k.a. “crazy Charles”. At the time, he used a “telescopic” treatment to treat obstructions. He would place 2 gradually larger tubes inside the arteries to dilate the obstructions. The probably most implanted coronary stent at the time was called the Palmaz stent, which would later be called the Palmaz Schatz stent because Dr. Schatz added a 1 mm bridge between two 7 mm-stent segments. With this addition the stent became more flexible and navigated the coronary arteries much better. The stent was characterized by its significant radial strength which, unlike the other stent used at the time, the so-called Gianturco Roubin stent with little radial strength but very much used to contain dissections and prevent acute occlusion. Dr. Palmaz usually attends the meetings held in our country and often visits and is a member of our college. The first report on the use of stents in human beings dates back to March 29th, 1986. I was Dr. Ulrich Sigward who used them for the first time in Switzerland. Also, we should mention Dr. Paul Puech with a mesh-covered self-expanding stent called Wallsttent.3

I still can remember that when we started using Palmaz stents in human beings in Argentina we had to administer anticoagulant therapy, which was very complicated due to bleeding and the large number of thrombotic occlusions reported. The technique we used for implantation was to mount the stent “by hand” before the angioplasty by squeezing it firmly into the balloon so it would not move, which sometimes happened. Also, stent deployment happened at very low pressures, and stents were underexpanded at times, which is something that conventional angiographies would not capture at the time. These problems were closely associated with the massive use of coronary stents. But in 1995, Dr. Antonio Colombo developed a new stenting technique in Milan, Italy. It was published in Circulation that year. A multicenter study on this unique technique was published the next year with what were called the “MUSIC criteria”.4 This technique simply consisted in implanting stents at very HIGH pressure to later check their proper expansion using IVUS (intravascular ultrasound) by completely covering the atherosclerotic plaque. With this correct expansion with good entry and exit of coronary flow and, above all, with the proper stent APPOSITION to the vessel wall, ANTICOAGULATION WAS AVOIDED and, consequently, all bleeding issues. Only dual ANTIPLATELET therapy was used. In addition, the proper expansion of the stent reduced acute occlusions dramatically.

We could say that: 1) Balloon angioplasty was “saved” by stent angioplasty, and 2) stent angioplasty was “saved” by Colombo with IVUS and high pressure.

Afterwards, in 1994 when the effectiveness of the stent was confirmed during coronary angioplasty, 2 multicenter studies were published with high rates of approval and massive use among interventional cardiologists. The STRESS trial was conducted in the United States, and the BENESTENT trial5 in Europe and ARGENTINA. We felt honored to be asked to participate in the latter as representatives of our country. These studies gained the stent the approval it needed from international regulatory agencies.

However, we still had unfinished businesses with coronary stents like stent restenosis due to myointimal cellular proliferation. Basically 2 different research lines were created for the management of restenosis, one was intracoronary radiation and the other one was based on the use of drug-eluting stents. Intracoronary radiation was inferior compared to drug-eluting stents and fell into oblivion. Then, drug-eluting stents kept moving forward. Basically, different drugs were used like the antiproliferative drugs paclitaxel, and sirolimus. Sirolimus or rapamycin largely exceeded the effectiveness of paclitaxel. In 1999 the tremendous potential of rapamycin (sirolimus-eluting stent) had already been confirmed in the experimental work in animals conducted by Dr. Robert Falotico in Cordis headquarters based in New Jersey, United States.6

Back in 2002, the NEJM published the very first prospective, randomized, and multicenter study led by Dr. Marie-Claude Morice that compared rapamycin-eluting stents to regular stents with a 6-month follow-up to assess restenosis. The result of the RAVEL trial7 conducted in Europe was devastating. Rapamycin-eluting stents had a rate of in-stent restenosis of 0% compared to non-pharmacological stents. The following year, 2003, a similar study called the SIRIUS trial was published in the United States with the same results. The very first rapamycin-eluting stent implanted in humans was performed by Dr. Edoardo Souza in Brazil back in 1999.

Parallel to rapamycin-eluting stents, other studies with paclitaxel-eluting stent were conducted called the TAXUS trials. In time, the effectiveness of sirolimus largely proved to be superior to paclitaxel, a drug not currently used for drug-eluting stents. Maybe the most important legacy that TAXUS trials left us was a score that was developed to know the morbidity and mortality rates of patients treated with stenting. It was conducted by Dr. Patrick Serruys and eventually referred to as the SYNTAX score.

After this first generation of stents, the second generation of stents starts what we would call “the stent war”. It marked the appearance of different stents with different metal structures, new drugs all derived from sirolimus, different classes of polymers and deployment times. Currently, there are polymer-free stents available with 2 drugs, all with a proven safety and efficacy profile. It is obvious that bare metal stents contributed significantly to the management of coronary artery disease. Catheter-based revascularization procedures have now proven better compared to surgical revascularization.

Advancements in the decision-making process: the multi-slice computed

tomography

So far we have made a description of the advancements made in interventional cardiology from the beginning until present day.

However, the biggest question that still remains is what new breakthroughs will show up in this thriving specialty with the capacity to change the decision-making process. Well, it seems that new diagnostic methods will probably be perfected in the field of ischemic heart disease

The most important change that is present and future at the same time is multslice computed tomography, which will probably be replacing diagnostic coronary angiography. Cath labs where cardiac catheterizations are performed will be spared for therapeutic procedures alone. This means that in the coming future, decision-making regarding percutaneous coronary intervention or surgical revascularizations will be based on non-invasive images only.8-11 Obviously, this prediction involves the disappearance of diagnostic cinefluoroscopy from conventional cath labs where cardiac catheterizations are performed, which in the future, will only be used as PCI capable cath labs.

Currently, numerous studies have been conducted to assess the decision-making process between the angiography and the computed tomography scan like the SYNTAX III Revolution clinical that compared decision-making process regarding revascularization between angiography and multi-slice computed tomography. However, once the computed tomography based decision-making process is behind us, the results of this decision-making are being assessed using multi-slice computed tomography. The ongoing Revolution CABG trial is conducting an ongoing investigation on planning and performing surgeries without previous cine coronary arteriography and multi-slice computed tomography guidance only. This will be an important first trial in humans that will be used to secure this concept.

Race is on for the conquest of other territories

Also, although we predicted some things would be lost, others will be gained too.

There are territories different from the coronary arteries that have already been conquered, some more consistently than others. Currently, the most important one is peripheral vascular territory—lower limbs mainly—which has been meticulously disputed by interventional radiologists mainly. However, this territory already has all the materials and resources needed to be handled correctly. The same thing happens with the management of aortic aneurysms, which is already part of structural heart diseases.

The “greatest” conquest of all for interventional cardiologists will be the cerebral territory, and they will be fighting this battle against interventional neurologists to treat strokes. Although the latter have already developed interventional procedures to treat hemorrhagic strokes, they don’t have the experience needed for the management of ischemic strokes.12 It is in this field that interventional cardiologists have already taken the lead since here one of the most important considerations to make is that patients need to be treated very fast. Interventional neurologists are not used to acting fast and still have not wrapped their minds around the fact that longer times equal more brain damage. The decade-long experience of treating acute myocardial infarctions has given interventional cardiologist the lead over interventional neurologists. Also, most of the elements used to treat ischemic strokes are perfectly well known by interventional cardiologists.

Interventional cardiology probably has other unfinished businesses we cannot anticipate today. However, the important takeaway is that this medical specialty does not begin and end in the management of coronary artery disease. A totally different thing are structural heart diseases, but I won’t be referring to them in this Editorial.

I wouldn’t want to go without leaving a final message on our medical specialty. This message revolves around the terms used to refer to our own specialty: interventional cardiology. This denomination is too encapsulated within the practice of heart procedures, which may have already shaped our mindset and thoughts tremendously. In turn, this may have limited us when our scope of action should go far beyond the coronary arteries since our playground is the entire human arterial tree. Therefore, this denomination should not be an obstacle to restrict our actions to coronary arteries alone. We already know how to treat cardiovascular diseases in the entire body, and this is what we should be doing. Also, we know how to handle different etiologies, not just etiologies of atherosclerotic origin. In the future our specialty will undoubtedly have to come to terms with other medical specialties dedicated to vascular procedures. Also, collaboration with interventional cardiologists, interventional radiologists, interventional neurologists, and vascular surgeons will be a common thing. This will eventually change our amazing specialty dramatically putting us, once again, in a new and different stage of evolution.

Rubén Piraino

Associate Editor of the Argentinian Journal of Interventional Cardiology

1. Gruntzig A. Transluminal dilatation of coronary-artery stenosis. Lancet 1978;1:263.

2. Baim DS, Kent KM, King SB III, et al. Evaluating new devices. Acute (in-hospital) results from the new approaches to coronary intervention registry. Circulation 1994;89:471-81.

3. Serruys PW, Strauss BH, Beatt KJ, et al. Angiographic follow-up after placement of a self-expanding coronary-artery stent. N Engl J Med 1991;324:13-7.

4. Serruys PW, Di Mario C. MUSIC Criteria. Circulation 1995;91:1891-3.

5. Serruys PW, de Jaegere P, Kiemeneij F, et al. A comparison of balloon expandable-stent implantation with balloon angioplasty in patients with coronary artery disease. Benestent Study Group. N Engl J Med 1994;331:489-95.

6. Rensing BJ, Vos J, Smits PC, et al. Coronary restenosis elimination with a sirolimus eluting stent: first European human experience with 6-month angiographic and intravascular ultrasonic follow-up. Eur Heart J 2001;22:2125-30.

7. Morice MC, Serruys PW, Sousa JE, et al. RAVEL. New Engl J Med 2002;346(23):1773-80.

8. Modolo R, Collet C, Onuma Y, Serruys PW. SYNTAX II and SYNTAX III trials: what is the take home message for surgeons? Ann Cardiothorac Surg 2018;7:470-82.

9. Collet C, Onuma Y, Andreini D, et al. Coronary computed tomography angiography for heart team decision-making in multivessel coronary artery disease. Eur Heart J 2018;39:3689-98.

10. Collet C, Miyazaki Y, Ryan N, et al. Fractional Flow Reserve Derived From Computed Tomographic Angiography in Patients With Multivessel CAD. J Am Coll Cardiol 2018;71:2756-69.

11. Norgaard BL, Leipsic J, Achenbach S. Coronary CT Angiography to Guide Treatment Decision Making: Lessons From the SYNTAX II Trial J Am Coll Cardiol 2018;71:2770-2.

12. Widimsky P. When will acute stroke interventions be as widely available as primary PCI? EuroIntervention 2017;13:1269-72.

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