Remembering the past to understand better and prepare the future may be a fruitful exercise. Having started coronary surgery (CABG) in 1968, 50 years ago, I have witnessed different periods. I have been one of the actors of a major paradigme shift in the revascularization procedures, i.e., the arterial stenting. I have also been one of the promotors of the most innovative techniques, un-properly called robotic surgery, in an attempt to circumvent the problems of a conventional CABG.
This wide perspective enables, at a time of technological tsunami, some reflexion for the future.

At start, very few cardiac surgeons could percieve the real role that CABG was going to have in the management of patients with coronary diseases. In addition, at that time, the technology was not geared to the needs of the surgeons. CPB itself was carrying a significant risk of iatrogenic complications with a massive consumption of blood products and a major inflammation. Myocardial protection did not exist. The instruments tailored for the specific requirements of small vessels surgery were not available. The operative loops and microscopes were in an infancy stage. The suture materials were not suitable for the of surgery on small vessels. Finally, the operative techniques were not appropriate. The importance of preserving the myocardium during the procedure was not yet demonstrated. The cause of the " stone heart syndrom " responsable for post operative cardiogenic shock had not been identified.
Not surprisingly, the clinical results were less encouraging than expected. The cardiologists were then quite reluctant to refer patients.

Various progress totally changed the situation within a relatively short period. Firstly, myocardial preservation techniques. At that time, the research programs performed were focused on the myocardial preservation to allow safe protection of the viability of the cardiac homograft after harvesting. Hypothermia appears to be one of the major components of the protocole. The scope of these studies were then extended to every routine cardiac procedures, including CABG.
Secondly, instrumentation. The progress in the instrumentation has been a major step forward. The development of coronary microsurgical instruments, inspired by the neurosurgeons, (Yasargyl in Vienna), and plastic surgeons, (Guy Owens in Melbourne, Alain Gilbert in France) has been made possible by the enthusiasm of some manufacturers. Ultra thin pick ups, fine needleholders meeting the requirements of fine surgery in a deep operative field, were designed and made available for cardiac surgeons.
In the mean time, in the early 70', a systematic evaluation of the healing process of the micro arterial anastomosis, of the venous autograft in a micro arterial interposition showed the role of the tissue mechanical trauma, of the tissue ischemia, of the suture technique itself and on the patency of the anastomoses. This led to the specific training protocoles and the organization of intensive courses in basic microsurgery dedicated to vascular surgeons.
It may be interested to note that the " giants " of cardiac surgery were not interested in adopting a precise, meticulous surgery and had a limited confidence in the future of the CABG surgery. Charles Dubost, my mentor, used to tell us, at start of a coronary case " do it yourself, now. When you are a senior resident, this stupid surgery will be gone ". Actually, the combination of a good myocardial preservation and a fine micro surgical technique for the distal coronary suture totally changed the panorama : post operative death rate decreased dramatically. Good patency rate of the grafts could be demonstrated by early post operative angiographic control. The first good data, in the mid 70's, were the starting signal of CABG surgery [1-4]. The numbers grew exponentially. A major change in the treatment of angina pectoris had occurred. The use of anti coagulant or anti aggregate therapy, a good physical rehabilitation and the strict control of the risk factors have significantly contributed to the improvement of the image of CABG. A ten years' period started in the mid 70' : the golden age of coronary surgery and the absolute reign of the surgeon (Figure 1).

The world of coronary surgery started being challenged in the late 70's : CABG starts to be the target of heavy attacks (Figure 2). The first one came from Swizterland. Andreas Gruentzig showed that balloon angioplasty could open an arterial stenosis. In the early 70's, he published his experience in peripheral arterial diseases and then moved to the coronary arteries. The first case of coronary angioplasty was performed in May 1977. The outcome was quite spectacular. However, it became obvious, with gaining experience, that the risk of re-stenosis, in the weeks and months following the dilatation, was the Achilles' tendon of the technique.
Novel alternative treatments were evaluated. The direct coronary endarterectomy was aiming at a complete restoration of the coronary artery diameter. The results, despite an potent anticoagulation and anti-aggregant therapy were quite disappointing. Direct percutaneous coronary recanalization using various types of Laser beam was evaluated in a few centers. Initial enthusiasm about this application of laser therapy turned rapidly into serious disappointment. Another quite original technique was evaluated: the Transmyocardial Laser Revascularization (TMR) creating transmural channels, permitting a direct perfusion of the ischemic myocardium from the ventricular chamber. This was achieved by a precise laser therapy (either with a Holmium:YAG laser or CO2 one), directly to an area of the heart muscle. Approximately 10-50 channels were made in each targeted region of the heart muscle. The technique gained rapidly a lot of attention, but it became obvious, with more experience, that the real impact on both clinical symptoms and survival did not meet the expectations.

In the early 80', a disruptive technique for the treatment of arterial lesions was published : a metallic coil could be introduced into the aorta, retrogradely, and positioned precisely under fluoroscopic control to maintain the vessel open, to reinforce a fragile arterial wall or to cover an aneuvrysm. For the small history, at that time, a Swedish engineer, retired in Swizerland, discovered at the Lausane Emergency Receiving Center how the wrist fracture of his aged wife was treated : a vertical traction on the fingers equiped with a " chinese glove ". The progressive traction permitted a slow reduction of the wrist fracture. When you pull on a flexible cylinder, you reduce the diameter of the cylinder ; when you release the traction, the flexible expandable tube gets back to its initial diameter. Transfering that to arterial coils : traction on the coil permits to reach a diameter allowing intra arterial progression. Releasing the traction, as the coil has reaches the planned landing zone, let the coil get back to its initial size and reinforce, as expected, the arterial wall. A new approach of the treatment of restenonis was born.

The Swedish retired engineer started a company, Medinvent, near Lausane. We were asked to evaluate the self-expandable device on animal models. The perfect endothelialization of the device could be observed on pig aortas, regardless of the structure of the coil, metallic or polyurethane, with a minimal sclerotic change of the media and no adventia response. The experimentation was then performed on smaller size pig vessels, the carotid and the femoral artery, with identical good results. Some micro thrombi deposits on the inner surface were however observed leading the coronary surgeon I am to worry about the fate of such devices in very small caliber arteries. In the mean time, it was considered that the word " coil " was quite cumbersome and inappropriate in the medical community. The coil took the name of " stent ", after the retired engineer Hans Wallsten ! [5].

Actually, the real development of arterial stenting started in the field of coronary arteries. However, the leading cardiologists did not expressed unbounded enthusiasm, leading us to approach the vascular interventional radiologists. Roussseau, from Toulouse, did the first 'in man' implantation. A young cardiologist at the CHUV in Lausane, Ulrich Sigwart, was quite enthusiastic and performed rapidly, in 1988, the first clinical cases of implantation of the Medinvent auto expandable stent in coronary arteries. The innovation was very well recieved at the meeting of the American College of Cardiology. The technique was adopted in almost every center of interventional cardiology. At the same period of time, Palmaz and Schatz published their own experience, with a non self expandable device. The fantastic adventure of a crazy idea had started, which was going to change totally the management of coronary patients. A market of billions of dollars was born [5].

The development of stenting has been fast. The technique is easily performed under local anesthesia through a single needle puncture. Obviously, this technique is far less aggressive than a sternotomy. Return to normal life is immediate. However, the risk of the acute thrombosis of the stent and its progressive restenosisis are still a concern. Biomaterial research should resolve the problem: new stent design, drug eluding stents, biodegradable stents are coming. The search of the ideal stent, the Holy graal, is quite safe: the next stent will be better than the one used before, and if the new stent fails, the procedure can be repeated. During this period, the surgical activity declined significantly. From 2001 to 2008, the number of CABG dropped, in the USA, from 1742 cases per million adult to 1081, as the number of PCI remained stable (3827). The business (about 6 billions USD per year) dropped by 23%. As a whole, the future the coronary surgery did not look favorable (Figure 3).

In the mean time, large multicenter randomized prospective trials (RCT) have been carried out by the medical and surgical scientific societies and heavly sponsored by the stent companies. One of them, the SYNTAX trial (Synergy of Taxus DES and Surgery) brought about the best informations. The patients, included in the trial, were selected, after a medical and surgical confrontation, for either a randomization (stent vs CABG) or two registries, one for stents, one for CABG. The publications of the results at one and five years follow up were accepted in the best journals (NEJM). The criticism usually made to large RCTs, performed on highly selected groups of patients, did not apply to this trial as it concerned all comers patients in experienced centers. The major consequence of the trial has been the publication of precise guidelines for the treatment of coronary artery diseases in every clinical situation (acute and stable), for every category of lesion, and association of risk factors.

The guidelines, accepted by the whole community, have dramatically changed the management of the patients and lead to a " peace treaty ". The optimistic scenario depicted in Figure 4 finally prevailed.

The creativity in the medical community is unbounded. The imperious necessity of opening new markets to maintain a high profitability and a two digits annual growth rates is driving the biomedical industry. In the mean time, the numerical revolution, based on artificial intelligence, deep learning and soon machine learning is changing the whole world. The consequences are immense, with a cascade of changes and a huge impact of every aspect of the health care delivery.

The surgeons have tried to respond to the progression of the interventional cardiology. They came up with new less invasive surgical techniques : small incisions, beating heart surgery without cardiopulmonary bypass. They proposed to improve long term results by using arterial conduits. Rapid anastomotic devices for the distal suture and for the proximal aortic suture of venous or arterial conduits were assessed. External graft support and pharmacological conditioning of the graft were evaluated... The most innovative progress was supposed to be the totally endoscopic coronary artery bypass, the TECAB, using the daVinci (Intuitive Surgical, Inc.) telemanipulator [6]. The experience started in the late 1900'. The cost issue made the developement quite slow. In addition, it appeared rapidly, in the early 2000', that the technology was actually not ready : the mechanical stabilization of the ventricle during the TECAB procedure itself was quite difficult, performing safely the coronary anastomosis was a real issue. The Intuitive Surgical re-oriented its development in the other specialities (urology, gynecology...) with a remarkable success. As a whole, the surgical community itself has not been convinced that these attempts of a minimally invasive technique were as safe and reproducible than conventional techniques. Rate of adoption remained quite low. This accounts for the reluctance from the cardiological community to consider these innovations as a real progress and the defiance from the patients.

In the mean time, the interventional cardiologists and the industry, has been very active and innovative. Totally new concepts have been brought up to characterize more precisely the coronary lesions and treat them percutaneously. At the diagnostic stage, multimodal imaging is developing rapidly. It combines non invasive techniques (MRI, 3D ultrasons, intravascular ultrasonography, optical resonance tomography, flow analysis and functional flow reserve...) to new systems based on conventional principles (3D rotational angiography). These various modalities may be integrated in the same machine, with a clear final goal : a more precise evaluation of the lesions and a more individualized therapy. Pre-operative simulation will very soon help in the selection of the best option in its smallest details (size of the catheter, optimal route, optimal landing zone of the stent...), the better radioprotection of the patient and the interventional cardiologist (robot for catheterization).

Evaluation and promotion of these innovations has been quite remarquable on a methodological point of view [7]. Training programs and huge meetings have been organized. The biomedical industry has played a major and growing role in the scenario : funding projects and new start ups, building huge conglomerates with an almost limitless financial power, sponsoring most of the clinical studies and playing a significative role in the decisions of the regulatory and health care agencies. The recent start of the " early feasability trial " policy at the FDA is permitting an enormous number of clinical trials. The result of this multi- facettes approach is that there is today almost no limit to any kind of percutaneous interventions for repair of the heart structure. Interestingly, this evolution is supported by the general population which is waiting eagerly for more precise early diagnosis and more successful methods to address the coronary diseases (diagnosis and treatment), to minimize its impact on quality and duration of life. It is easier to get a stent than to correct risk factors and have a good lifestyle!

The technological tsunami is impacting the organization of hospitals and the daily practice. It makes mandatory, for obvious financial reasons, the development of hybrid suites, combining the possibility of a surgical intervention and sophisticated percutaneous procedures. This has a huge impact on the organization of the hospitals.

This means also a total revolution in the relationship between the two actors, the cardiac surgeon and the interventional cardiologist. The key decision (" what is the technology which fits the most to the individual patient " ?, and not anymore " which technique fits the best to the doctor " !) will be shared in an happy family of high performers without egos during a permanent communication. Each party will integrate the issues of the partner. In this patient centered decision making procedure, guidelines are the golden rule, and experience of everybody will be potentialized by other's experience. This change in the relationship between diverse cultures will require a lot of commitment from each part of the team.

It will, at the very end, impose to reconsider the whole health care policy : the present rule, the 'fee for service' is not anymore suitable. The concept of payment for the added value will soon prevail. It might help to end the present uncontrolled rise in health care expenditures. Progress in machine learning should facilitate the transition to a system based on real facts.

The past 50 years have permitted a huge development of active treatment of coronary artery diseases. Surgery has open the way. Interventional cardiology, supported by a large variety of technical innovations, has grown explosively. This has a huge impact on patient's life and on health care delivery systems. Further developments are still to come based, on other specialties such as genetic diagnostic, gene editing and engineering, non invasive tissue characterization.

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7. Morice MC, Serruys PW, Kappetein AP, et al. Outcomes in patients with de novo left main disease treated with either percutaneous coronary intervention using paclitaxel-eluting stents or coronary artery bypass graft treatment in the Synergy Between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery (SYNTAX) trial. Circulation. 2010;121(24):2645-253.