EDITORIAL COMMENT
Left Main Percutaneous Coronary Intervention Crossing the ThresholdTime for a Guidelines Revision!*
Jeffrey W. Moses, MD*,
Martin B. Leon, MD and
Gregg W. Stone, MD
Columbia University Medical Center/New York Presbyterian Hospital and the Cardiovascular Research Foundation, New York, New York
* Reprint requests and correspondence: Dr. Jeffrey W. Moses, Columbia University Medical Center and Cardiovascular Research Foundation, 161 Fort Washington Avenue, New York, New York 10032 (Email: jm2456{at}columbia.edu).
Key Words: percutaneous coronary intervention • left main CAD • chronic CAD
Surgery with coronary artery bypass grafting (CABG) has been the standard of care for obstructive left main coronary disease for more than 3 decades. The benefits of CABG as exemplified in the Coronary Artery Surgery Study coupled with the dismal early outcomes of percutaneously treating left main disease with balloon angioplasty created a "forbidden zone" for interventionalists (1,2).
Over the last several years, this "terra incognita" has been invaded by interventionalists on a widespread scale. A current literature search revealed more than 200 peer-reviewed citations in the past 30 months (including more than half a dozen editorials in major cardiology journals) dedicated to the subject of left main percutaneous coronary intervention (PCI). Much of these data stem from a renewed enthusiasm for left main intervention with drug-eluting stents (DES), reinforced by meta-analyses of randomized trials indicating equivalent 5- to 10-year rates of mortality and myocardial infarction in patients undergoing multivessel PCI compared with CABG (3,4). Favorable recent studies of left main DES include single-center registries (5), propensity-matched cohorts compared with CABG (6), meta-analyses of multicenter registries (7,8), and most importantly, the 705-patient left main subset analysis of the SYNTAX (Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) randomized trial (9). The diversity and richness of these data sets are themselves a clear indication that left main PCI is now in widespread clinical practice across the globe.
In this context, LE MANS (Unprotected Left Main Stenting Versus Bypass Surgery) Registry collaborators should be congratulated. In this issue of the Journal, they report an 11-year collaborative effort that began in 1997 in a single country to evaluate the outcomes of left main PCI (10). In the course of this investigation, they also conducted a previously published modest-sized successful randomized trial comparing bare-metal stenting with CABG (11). The highly selected 252 patients in the current report represent a heterogeneous cohort, given the evolution of technique and technology during the course of the study inclusion time span. Nonetheless, certain conclusions can be drawn from their observations: 1) left main stenting in skilled hands can be performed with low morbidity and mortality with no late "catch-up"; 2) DES have improved clinical outcomes compared with bare-metal stents, principally by substantially reducing the need for repeat revascularization; 3) the rates of early, late, and very late thrombosis are low despite the limited use of dual antiplatelet therapy after 2 years with both stent types; and 4) long-term survival after left main stenting is excellent in those patients with left main disease without concomitant 3-vessel disease.
The power of these observations are somewhat limited by a lack of randomization against surgery (or even a matched control group from the 1,700 CABG surgeries performed in these centers during this period), the small numbers of patients followed beyond 4 years, and the even smaller numbers treated with DES with late follow-up. Nonetheless, there is striking concordance when these findings are compared with both recent large observational registries and emerging data from the left main subset of the SYNTAX trial, in which paclitaxel-eluting stents compared with CABG in patients with left main disease and either low- or moderate-risk coronary artery anatomic complexity resulted in comparable or lower rates of composite major adverse cardiovascular events.
Thus, in 2009, the weight of evidence supports the position that: 1) left main PCI with DES of the ostium or shaft can be performed with very low morbidity and mortality and with very low rates of repeat revascularization; 2) stenosis of the distal left main can be effectively treated with a single "crossover" stent in the majority of cases and has become the current preferred strategy; 3) stent thrombosis of the left main segment is infrequent; and 4) PCI with DES will result in noninferior outcomes to CABG in many patients with unprotected left main disease, although selected patients with very complex and/or triple-vessel disease still benefit from a primary surgical approach.
Numerous technical issues remain that need to be addressed in future clinical studies. Many would dispute the LE MANS group predilection for direct stenting. Many experienced left main treatment aficionados strongly favor aggressive lesion preparation and/or intravascular ultrasound guidance. The threshold for stenting both limbs of the distal left main bifurcation and the optimal bifurcation technique vary considerably among operators (12). And lastly, special consideration must be given to patients in whom long-term dual antiplatelet therapy may be problematic because of compliance issues, bleeding diatheses, or concomitant use of vitamin K antagonists.
Based upon the mounting evidence, there can be little dispute at this juncture that PCI can be offered as a safe alternative to CABG for a significant number of patients with left main disease, particularly nondiabetics without extensive concomitant coronary artery disease. Left main PCI no longer needs to be confined to those patients who adamantly refuse or who are at unacceptably high risk for CABG. As such, there is now sufficient clinical trial data to justify a relaxation of the American College of Cardiology/American Heart Association guidelines, such that left main PCI is no longer a Class III indication.
From a broader perspective, left main disease should be viewed as an extreme case of chronic coronary artery disease with a particularly large area of myocardium at risk in which revascularization is the preferred initial treatment strategy. The concept of appropriately risk stratifying patients is vital to the question of which patients with chronic coronary artery disease benefit from revascularization in general and by PCI in particular. Recent data from the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial, including the nuclear substudy and analysis of patients with silent ischemia, indicate that in patients with an important ischemic burden, PCI is superior in reducing ischemia and in improving outcomes compared with medical therapy alone (13,14). This position is also supported by the recently published JSAP (Japanese Stable Angina Pectoris) and BARI (Bypass Angioplasty Revascularization Investigation) 2-dimensional randomized control trials, indicating superiority of revascularization versus medical therapy in patients with either documented ischemia or a large amount of myocardium at risk (15,16). Such observations should be placed in context with the SYNTAX trial, in which PCI with DES was either superior or equivalent to CABG as a revascularization strategy in patients with isolated left main disease or accompanying single- or double-vessel disease (9). Only in the most complex patients with left main and associated 3-vessel disease was CABG a superior revascularization choice. Thus, in circumstances of significant myocardium at risk (including the extreme case of left main disease), PCI improves clinical outcomes and provides a preferred therapy alternative, even in patients with so-called "stable" coronary artery disease.
Undoubtedly, there is sufficient equipoise to justify a definitive multicenter, prospective, randomized, controlled trial comparing DES with CABG to more clearly identify the optimal revascularization pathways for individual patients with unprotected left main disease. Such a trial must have sufficient power to determine important differences in critical clinical end points such as death, myocardial infarction, and stroke, and also must be stratified to examine important anatomic, clinical, technique-related, and ischemic variables. However, the results from such a definitive study are many years away, and in the interim, practicing physicians must make clinical decisions on the basis of the best available evidence. The long-term LE MANS data adds to the growing literature indicating that in many patients, left main stenting can be offered as a safe and effective alternative to surgery. However, because quality assurance indicators are often "guidelines driven," until there is a change in the formal guidelines to more accurately reflect the consensus shift in physician practice, the approach to left main revascularization will remain suspended in the past, reflecting the conundrum of infrequently revised guidelines and appropriateness criteria based on outdated literature (17). The rapid advancement of medical technology combined with the telescoping and globalization of evidence-based medicine requires that critical practice guidelines be continuously updated to provide our patients with the safest, most effective, and least invasive therapies in a timely fashion.
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Footnotes
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Dr. Moses has served as a speaker for Cordis and Abbott (modest).
* Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology. 
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References
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