AMSTERDAM – In patients with acute ST-segment elevation myocardial infarction, stenting of significant coronary stenoses not responsible for the infarction as well as the infarct-producing lesion led to substantially better outcomes than an intervention that only targeted the infarct-related stenosis in a randomized, multicenter trial with 465 patients.
The results appeared to refute the prevailing recommendation from cardiology societies to limit the percutaneous coronary intervention (PCI) done during acute treatment of ST-segment elevation myocardial infarction (STEMI) to the infarct-related lesion, especially when the secondary lesions are not clearly causing ongoing hemodynamic instability.
The new findings "make it clear that preventive PCI is a better strategy than restricting a further intervention to those patients with refractory angina or a subsequent myocardial infarction," Dr. David S. Wald reported on Sept. 1 at the annual congress of the European Society of Cardiology. Simultaneous with Dr. Wald’s report, the results appeared in an article published online (N. Engl. J. Med. 2013 [doi:10.156/NEJMoa1305520]).
Current guidelines on management of STEMI recommend PCI for the infarct-related artery only (Eur. Heart J. 2012;33:2569-619; Circulation 2013;127:529-55), primarily because, until now, scant evidence existed that a different strategy helped patients. "This uncertainty has led to variations in practice, with some cardiologists performing immediate preventive PCI in spite of the guidelines, some delaying preventive PCI until recovery from the acute episode, and others limiting the procedure to patients with recurrent symptoms or evidence of ischemia," noted Dr. Wald, an interventional cardiologist at the Wolfson Institute of Preventive Medicine of the Queen Mary University of London.
Mitchel L. Zoler/IMNG Medial Media
Dr. David Wald
Dr. Wald acknowledged, however, that his study did not address whether patients would be better served by a staged approach that delayed preventive PCI of significant, noninfarct related stenoses in a second PCI procedure, whether the benefits extend to treating noninfarct stenoses that occlude less than half of a coronary artery, and whether a similar strategy would help patients with non-ST–elevation MI (NSTEMI).
The Preventive Angioplasty in Acute Myocardial Infarction (PRAMI) trial enrolled consecutive patients of any age at five U.K. centers during April 2008 to January 2013. The study focused on STEMI patients because patients with a NSTEMI often do not have a clearly identifiable infarct-related artery. In addition, to qualify for entry, the patient’s infarct-related artery had to have been successfully treated by PCI and they had to have at least one other coronary artery with at least 50% stenosis judged treatable by PCI. Patients with coronary anatomy more appropriately treated with bypass surgery were excluded. The enrolled patients averaged 62 years of age, about three-quarters were men, and about 18% had diabetes. Roughly two-thirds had a second coronary artery with a greater than 50% stenosis, and the remaining patients had two coronary arteries with a significant lesion.
After successful treatment of the infarct-producing artery, patients with additional, significant lesions judged appropriate for PCI were randomized to either have their other significant lesions treated during the same procedure or to undergo no further intervention. This resulted in an average of 1.36 additional arteries undergoing PCI in the 234 patients randomized to the more aggressive protocol.
Following the PCI procedures, all patients received standard medical treatment: daily treatment with aspirin and a second antiplatelet drug, clopidogrel (Plavix), prasugrel (Effient), or ticagrelor (Brilinta). About 95% of patients in both study arms also received treatment with a statin, and about 90% received a beta-blocker and an angiotensin-converting enzyme inhibitor.
During an average follow-up of 23 months, the combined rate of death from cardiac causes, nonfatal MI, or refractory angina – the study’s primary endpoint – occurred in 9% of the patients randomized to immediate PCI of their noninfarct-related stenoses and in 23% of the 231 patients in the control arm, a statistically significant difference. The 14-percentage-point absolute reduction in endpoints translated into a 65% relative risk reduction. The rate of cardiac death or nonfatal MI was 5% in the patients who received added PCI while in the catheterization laboratory and 12% among those only treated in their infarct-related artery, also a statistically significant difference.
Additional analyses also showed statistically significantly lower rates of both nonfatal MI and refractory angina in the patients treated in multiple arteries when these endpoints were tallied individually and a strong trend toward fewer cardiac deaths in these patients as well. Kaplan-Meier analysis showed that the risk reduction in the preventive-PCI group was evident after 6 months of follow-up and then increased with continued follow-up.
These results were not materially affected by patient age, sex, diabetes status, infarct location, or the number of coronary arteries with significant stenoses. In addition, the complication rates, including procedure-related strokes, bleeding requiring transfusions or surgery, and contrast-induced nephropathy requiring dialysis, were similar in the two study arms.