PCI and surgery: The SYNTAX trial one year on

Reported from the ESC Congress 2009

Topics: Percutaneous Cardiovascular Intervention (PCI)

Date: 30 Aug 2009

Patrick Serruys, pictured left, and Scot Garg from Erasmus University Rotterdam, Netherlands, propose that the SYNTAX study has not changed contemporary practice, but has provided the missing evidence to justify the use of PCI in a select group of patients with complex disease.

In the 12 months following presentation of the preliminary results of the SYNTAX study here at the ESC, there has been extensive debate and discussion over the trial’s results, together with the SYNTAX score in defining the management of patients with triple vessel disease and left main stem lesions.

One year on, and the SYNTAX score has been introduced to the wider cardiology community through its own dedicated website (http://www.syntaxscore.com/), which, following its successful launch in May this year, has had over 15,000 hits. The score can be used to risk stratify patients; however, its primary role is to ensure that the angiograms of these complex patients are studied with the scrutiny they deserve, helping to aid the decision about the optimal method of revascularization.


The complex coronary artery disease seen in patients enrolled in the SYNTAX trial

In our clinical practice the SYNTAX score is playing a central role in the increasingly important assessment of the risk and benefit of performing a complex PCI. We are also finding it a vital piece of information to have for discussion with our surgical colleagues.

I am often asked whether the results of the SYNTAX study will change clinical practice. The study concluded that CABG remains the standard of care for these complex patients; however, the reality is somewhat different. An assessment of worldwide clinical practice in 2004 indicated that 29% of patients with complex disease were already having PCI, despite the absence of any supportive evidence and against all guidelines. The SYNTAX study, which was specifically designed to reflect real world practice, has indicated that in 2009, for two-thirds of patients with complex coronary disease, cardiac surgery is still the optimal method of revascularization. In the remaining one-third, PCI offers a suitable alternative. However, a full and frank discussion between doctor and patient is required to ensure that a completely informed decision is made.

One year on, I don’t think the SYNTAX study will change contemporary practice, but it has provided the missing evidence to justify the use of PCI in a select group of patients with complex disease. Historically, these patients were already being selected by interventionalists for PCI; these decisions are now justified by clinical evidence, and, by utilising the SYNTAX score, these patients can be identified more systematically. One important take-home message from the study is that the method of revascularization must be individualised taking into account not only coronary anatomy but also the patient’s co-morbidities and personal preference.

.....while cardiac surgeon Patrick Nataf from the Bichat Hospital in Paris finds a continuing synergy between PCI and CABG. Surgical revasularisation of the myocardium, he reports, has - like interventional cardiology - also witnessed major advances.
Advances in PCI have given this therapeutic option a key and irrevocable role in the management of CAD. The indications have spread to include triple vessel disease and left main stem lesions, which were classically considered exclusive surgical territory. Surgeons are thus confronted with performing more complex, multiple vessel coronary revascularization or after failure of PCI. It was high time to evaluate the two major techniques of myocardial revascularization in comparable populations.

SYNTAX, the results?
The Synergy between PCI with Taxus and Cardiac Surgery (SYNTAX) trial is a prospective clinical trial designed to compare current surgical and percutaneous techniques in patients with three-vessel or left main coronary artery disease (or both). The surgical technique for CABG, the approaches used for stent implantation, and the post-procedure medication were chosen according to local clinical practice. The primary endpoint, the non-inferiority of PCI as compared with CABG in the 12-month rate of major adverse cardiac or cerebrovascular events, was not demonstrated; CABG proved to be superior. In an analysis of secondary endpoints, the two treatment groups had similar rates of the primary composite endpoint (death from any cause, stroke, or myocardial infarctionn) (7.6% for PCI and 7.7% for CABG). Patients undergoing PCI were more likely than those undergoing CABG to require repeat revascularization (13.5% vs 5.9%) but were less likely to have a stroke (0.6% vs 2.2%).

The limits of the study?
The study has an excellent design and is a landmark in the field. However, the investigators did not discuss whether the strokes were related to the procedure or influenced by differences in the occurrence of atrial fibrillation, use of antiplatelet agents, or presence of risk factors for atherosclerosis. Among its other limitations is that patients who underwent CABG were less likely to receive optimal medical therapy (statins, aspirin or other antiplatelet agents, and ACE inhibitors or angiotensin II–receptor antagonists). Even more important is the choice of bypass conduit, which is a dominant factor in the long-term follow-up of CABG.

SYNTAX score, an excellent by-product
One interesting product of the study is the SYNTAX score. The more complex the coronary anatomy - ie, the higher the SYNTAX score - the better the outcomes of CABG as opposed to PCI. If the SYNTAX score is low, the two therapies seemed comparable in terms of outcomes. This Score taken together with the clinical profile will help in patient selection for the most appropriate technique.

Why SYNTAX does not represent the best surgical management of CABG?
“The internal thoracic artery: The drug eluting graft!”
Only 18.9% of patients in the SYNTAX trial had pure arterial CABG. While the saphenous vein has been considered as the predominant graft, venous graft atherosclerosis continues to be the major cause of late failure of CABG.


Complete myocardial revascularisation with exclusive mammary arterial gratfs

Parallel to improvement in interventional cardiology and progress from bare metal to drug-eluting stents, surgical revascularisation of the myocardium has also undergone major advances. The ITA has demonstrated superior long-term clinical results after CABG compared to saphenous vein grafts, with 85-95% freedom from significant stenosis at 7-10 years. Moreover, the ITA outperforms other arterial grafts, namely the radial and gastroepiploic arteries, and is now undeniably the conduit of choice for surgical revascularization. The structure of the ITA is adapted to arterial pressures and high flow rates, and produces greater amounts of relaxing factors, nitric oxide providing a superior reactivity to flow requirements in the coronary arteries.

The use of both ITA has demonstrated additional advantages over the use of single ITA in combination with vein grafts. Bilateral ITA grafting is an independent predictor of improved long-term survival and freedom from recurrence of angina, late MI, re-operation, angioplasty and other cardiac-related events.

Authors: Patrick Serruys and Scot Garg, Eramus University, Rotterdam, Netherlands

Patrick Nataf, Cardiac Surgery Department, Bichat Hospital, Paris, France

Notes to editor
The SYNTAX trial: one year on, Monday 31 August 16:30-18:00, Madrid – Zone 6, FPN 2856-2859