On Mar. 30, 2020, invasive procedures such as bypass surgery and stenting-commonly used to treat blocked arteries were no better at reducing the risk for heart attack and death in patients with stable ischemic heart disease than medication and lifestyle changes alone. However, such procedures offered better symptom relief and quality of life for some patients with chest pain, according to two new, milestone studies.

The studies, designed to settle a decades-old controversy in cardiology, appear online March 30 in the New England Journal of Medicine. While researchers released preliminary findings last November at the American Heart Association annual meeting, the papers published today report the official outcomes of the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA), the largest and one of the most consequential studies of its kind.

Funded by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health, the trial followed more than 5,000 patients with stable heart disease and moderate to severe heart disease for a median of 3.2 years. It compared an initial conservative treatment strategy to an invasive treatment strategy. The conservative treatment strategy involved medications to control blood pressure, cholesterol, and angina (chest discomfort caused by inadequate blood to the heart), along with counseling about diet and exercise. The invasive treatment strategy involved medications and counseling, as well as coronary procedures performed soon after patients recorded an abnormal stress test. The trial allowed tests that assess coronary blood flow restriction, called ischemia, to determine who could participate in the study.

By the end of the trial, the death rate between the two groups proved to be essentially the same: among the participants who had invasive procedures, 145 died, compared to 144 who received medication alone. The overall rate of disease-related events was similar among those who took medication alone: 352 experienced an event such as heart attack, compared to 318 who had invasive procedures.

Researchers noted one caveat; patients in the conservative strategy had fewer cardiovascular events during the first two years of the study. However, the invasive strategy patients had fewer events during the last two years, researchers noted, because of an uptick in heart attacks in that group in the first six months.