ISCHEMIA Trial: Invasive Treatment Only Better for Angina Burden.
Abstract
Among patients with stable ischaemic heart disease and moderate-to-severe ischaemia on non-invasive stress testing, routine invasive therapy failed to reduce major adverse cardiac events compared with optimal medical therapy, although quality of life measurements in patients with angina did significantly improve.
In the largest study of its kind, the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial randomly assigned 5,179 patients with coronary artery disease at 320 sites in 37 countries to receive 1 of 2 treatment strategies: either “invasive” therapies including early stent implants or bypass surgery or so-called “conservative therapy”, where patients received only medication (e.g. aspirin, statins) and lifestyle advice. Prof. Judith Hochman (New York University School of Medicine, USA) presented that with a median follow-up of 3.3 years there were no differences between the 2 groups in the rate of occurrence for a group of 5 events: cardiovascular death, myocardial infarction (MI), hospitalisation for unstable angina, hospitalisation for heart failure, or resuscitation after cardiac arrest (HR 0.93; 95% CI 0.80-1.08; P=0.34) [1].
The curves crossed at 2 years follow-up, with absolute rates favouring the conservative therapy at 6 months by 1.9%. Yet, at 4 years, the data favoured early angiography followed by percutaneous coronary intervention (PCI) or bypass surgery by 2.2% (13.3% vs 15.5%, respectively). This poses the question of what even longer term follow-up will bring.
The major secondary endpoint of cardiovascular death or MI also showed no differences between the 2 groups (11.7% vs 13.9%; HR 0.90; 95% CI 0.77-1.06; P=0.21). All-cause death rates were similarly low between the invasive and conservative groups (6.5% vs 6.4%; HR 1.05; 95% CI 0.83 – 1.1).
In a parallel quality of life study, presented in the same session by Dr John Spertus (Saint Luke’s Mid America Heart institute, Kansas City, Missouri, USA), revascularisation provided greater relief for angina than conservative therapy, with half of the patients reporting to be angina-free at 1 year versus just 20% of those managed with conservative therapy alone [2].
Although the overall interpretation of this trial was negative, there were mixed findings with evidence for both harm and benefit. The data signifies that: 1) invasive therapy for stable ischaemic heart disease patients needs to be carefully considered in the context of angina burden and background medical therapy, and 2) there is a likelihood that optimal coronary revascularisation can be achieved with low procedural complications.