Preventive Angioplasty in Myocardial Infarction?
Abstract & Commentary
By Andrew J. Boyle, MBBS, PhD
Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco
Dr. Boyle reports no financial relationships relevant to this field of study.
Source: Wald DS, et al. Randomized trial of preventive angioplasty in myocardial infarction. N Engl J Med 2013;369:1115-1123.
Primary percutaneous coronary intervention (PCI) is the optimal treatment for patients suffering ST-elevation myocardial infarction (STEMI). Current guidelines recommend treating the infarct-related artery, also known as the culprit artery, during the initial primary PCI procedure, and strongly recommend against treating stenoses in other arteries at the same sitting (unless the patient is in cardiogenic shock). However, many patients with STEMI also have significant stenoses in other arteries, and there is a growing body of literature that demonstrates complete revascularization is associated with better long-term outcomes. Wald and colleagues extend the principle of complete revascularization to the setting of primary PCI. They performed a randomized, controlled trial of culprit-only PCI vs also treating stenoses > 50% in the non-infarct arteries (which they termed preventive PCI) at five centers in the United Kingdom.
The authors enrolled 465 patients presenting with STEMI (including three patients with left bundle-branch block) who were undergoing infarct-artery primary PCI and also had stenoses > 50% in other coronary arteries, and randomly assigned them to either preventive PCI (n = 234) or no preventive PCI (n = 231). They excluded patients whose other stenoses were chronic total occlusions or left main disease. The majority of patients received drug-eluting stents. The use of glycoprotein IIb/IIIa inhibitors and/or bivalilrudin was left to the operator’s discretion and these agents were used in 79% of cases. Importantly, further PCI after the index primary PCI was recommended only for refractory angina with objective evidence of ischemia. At discharge from hospital, the medical therapy was excellent in both groups (100% of patients on dual anti-platelet therapy, > 95% on statins, 90% on beta-blockers). The primary outcome was a composite of death from cardiac causes, nonfatal myocardial infarction, or refractory angina.
The data safety monitoring committee recommended that the trial be stopped early. During a mean follow-up of 23 months, the primary outcome occurred in 21 patients assigned to preventive PCI and in 53 patients assigned to no preventive PCI (infarct-artery-only PCI), which translated into rates of 9 events per 100 patients and 23 per 100, respectively (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.21-0.58; P < 0.001). HRs for the three components of the primary outcome were congruent: 0.34 (95% CI, 0.11-1.08) for death from cardiac causes, 0.32 (95% CI, 0.13-0.75) for nonfatal myocardial infarction, and 0.35 (95% CI, 0.18-0.69) for refractory angina. These benefits were statistically significant by 6 months after the index procedure. The authors conclude that in patients with STEMI and multivessel CAD undergoing infarct-artery PCI, preventive PCI in non-infarct coronary arteries with major stenoses significantly reduced the risk of adverse cardiovascular events as compared with PCI limited to the infarct artery.
This study will challenge current paradigms. The American College of Cardiology/American Heart Association guidelines give a class III recommendation for non-infarct artery PCI at the same time of primary PCI. Data from large registries indicate that staged PCI of non-infarct arteries resulting in complete revascularization leads to better outcomes than medical therapy in patients with STEMI. The current paper by Wald et al suggests that complete revascularization can be safely achieved during the initial procedure. Early reports of adverse outcomes from PCI to non-culprit arteries during primary PCI were in the era before intensive antiplatelet and statin therapy, and may therefore no longer be applicable. Perhaps optimization of medical therapy has expanded the role for PCI in these patients to now include multivessel PCI in the acute setting.
The results of this study are strengthened by the fact that all components of the primary combined endpoint were congruous and of similar magnitude, and by the statistically rigorous trial design and execution. It is important to note that the authors screened more than 2400 patients with STEMI to find 465 who fit their inclusion and exclusion criteria. Left main disease and chronic total occlusions were notable exclusion criteria. Also, they excluded patients with cardiogenic shock, who are known to benefit from multivessel PCI. Although this study makes a case for complete revascularization in selected patients with STEMI, it does not clarify when. It may well be that a staged procedure at a later date is the superior strategy. We probably should not change our practice until more data are available.