On November 16, 2019, the article, “ISCHEMIA: Invasive Strategy No Better Than Meds for CV Events," was published in TCTMD. The story highlights a presentation from the 2019 American Heart Association Scientific Sessions that showed patients with severe but stable ischemic heart disease who underwent routine procedures like stent implantation or bypass surgery didn’t fare better in the long-term than those who received optimal medical therapy and lifestyle advice alone.
Dr. Thomas E. MacGillivray describes the article, what it means for the cardiothoracic surgery specialty, and his view on the topic of lifestyle changes and medications vs. stents or bypass surgery.
The major finding of the ISCHEMIA trial was that an initial conservative strategy of optimal medical therapy was as effective as the invasive strategy. At 6 months, conservative therapy appeared more favorable; whereas at 4 years, the invasive strategy looked better. The curves for the primary and major secondary endpoints crossed at the 2-year time point. The incidence of myocardial infarctions was similar in both groups, but procedural myocardial infarctions were higher in the INV group and spontaneous myocardial infarctions were higher in the CON group.
From the perspective of a cardiac surgeon, the findings of the ISCHEMIA trial do not add any new or disruptive information. This trial reinforces the well-established recommendation that optimal medical therapy is effective treatment for many patients with stable ischemic heart disease even with severe ischemia on stress testing. The ISCHEMIA trial does not negate or even contradict the multiple previous clinical trials demonstrating the superiority of surgical revascularization over medical therapy (or PCI) in patients with specific anatomic patterns of coronary artery disease. Of note, the ISCHEMIA trial excluded from enrollment patients with evidence-based benefit for revascularization including: significant left main disease, multi-vessel disease with severely impaired left ventricular function, ischemic heart failure, acute coronary syndromes, and unstable angina.
The trial included stable patients with at least a 50% stenosis on CCTA in one major epicardial vessel, the majority of which would not have met evidenced-based guidelines for surgical revascularization. Less than half of the patients had three-vessel coronary artery disease. Although 87% of the patients had disease in the left anterior descending artery (LAD), less than half of the patients had proximal LAD disease. Perhaps these findings explain why the majority (74%) of the patients who underwent revascularization received PCI rather than CABG. Although analyzed in this study as the same treatment, CABG vs. PCI are distinctly different interventions with demonstratively different outcomes.
The ISCHEMIA trial does not negate or even contradict the multiple previous clinical trials demonstrating the superiority of surgical revascularization over medical therapy (or PCI) in patients with specific anatomic patterns of coronary artery disease.
The conclusion of the ISCHEMIA trial implies that the two randomized groups received distinctly different treatments yet there were a large number of crossovers. That is, 20% of patients in the INV group did not undergo revascularization, and 23% of the patients in the CON group underwent revascularization in addition to OMT. This reflects the real world practice that optimal medical therapy and coronary revascularization are complementary rather than competitive management strategies.
In large trials, composite endpoints can be statistically clear yet clinically opaque. These data points, like the disease, may potentially progress over time. Perhaps with longer follow-up the conclusions will be different. In the meantime, the appropriate management of coronary artery disease continues to be optimal medical therapy with appropriate utilization of evidenced-based guidelines for revascularization.
Thomas E. MacGillivray, MD, is the Chief of Cardiac Surgery and Thoracic Transplant Surgery, as well as the Jimmy Howell Endowed Chair in Cardiovascular Surgery, at Houston Methodist Hospital.