Invasive Intervention or Not? How to Treat Coronary Disease
by Adrienne Mueller, PhD
June 1, 2020
Coronary disease, the cause of heart attacks, is the most common cause of death in the United States. Established treatments for coronary disease are noninvasive medical therapies such as lifestyle interventions and drugs, and invasive revascularization procedures to open arteries with stents or go around obstructions with bypass surgery. Unfortunately, these invasive methods do not yield clear and unambiguous improvements in patient outcomes. Observational studies suggest that patients with moderate or severe ischemia (lack of blood flow to the heart caused by narrowed coronary arteries) have better survival if they undergo revascularization.
A team of scientists formed the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) to analyze the best management strategy for patients with stable ischemic heart disease. Led by Dr. David Maron of Stanford University and Dr. Judith Hochman of New York University, they performed a clinical trial with over 5000 patients to determine whether invasive treatment actually improves outcomes for patients with coronary disease. They assigned patients with moderate or severe ischemia to two groups. The first group underwent an invasive management strategy, with invasive angiography followed by stenting or bypass surgery alongside noninvasive therapies. The second group was treated with a conservative strategy, with invasive procedures reserved for failure of medical therapy. They then determined whether invasive interventions improved patient outcomes, such as decreasing fatal and nonfatal heart attacks.
Statistically, the answer is no. At six months: a higher proportion of patients in the invasive-strategy group had cardiovascular events than in the conservative-strategy group (5.3% vs 3.4%). At five years, the opposite was true: 16.4% of patients in the invasive-strategy group had events compared to 18.2% of patients in the conservative-strategy group. At neither time point, six months or five years, were the differences between invasive-strategy outcomes and conservative-strategy outcomes statistically significant.
This study, recently published in the New England Journal of Medicine, draws important attention to the fact that invasive interventions may not actually improve clinical outcomes. A companion paper in the same issue of the journal described that patients assigned to the invasive strategy had greater improvement in symptoms than those assigned to the conservative strategy. The ISCHEMIA trial highlights the need for shared decision-making between patient and clinician when considering stenting or bypass surgery. The investigators hope to receive funding for long-term follow-up to see if a survival benefit emerges from an invasive strategy.
Lead author David Maron is the Director of the Stanford Prevention Research Center, Director of Preventive Cardiology at Stanford and member of Cardiovascular Institute, and senior co-author Robert Harrington is Chair of the Department of Medicine, Professor of Medicine, and Director of Clinical Investigation at the CVI.