Prognostic value of coronary CTA vs. exercise treadmill testing: results from the Partners registry.

Abstract

We sought to compare the complementary prognostic value of exercise treadmill testing (ETT) and coronary computed tomographic angiography (CTA) among patients referred for both exams. We studied 582 patients without known coronary artery disease (CAD) who were clinically referred for ETT and CTA within 6 months. Patients were followed for cardiovascular (CV) death, non-fatal myocardial infarction (MI), or late revascularization (>90 days), stratified by Duke Treadmill Score (DTS) and CAD severity (≥50% stenosis). Mean age was 54 ± 13 years (63% male). In median follow-up of 40 months, there were 3 CV deaths, 7 non-fatal MIs, and 26 late revascularizations. ETT was inconclusive in 23%, positive in 31%, and negative in 46%. CTA demonstrated no CAD in 37%, non-obstructive CAD in 28%, and obstructive CAD in 35%. Among low-risk ETT patients (n = 326), there were 3 MI, 10 late revascularizations, and the frequent presence of non-obstructive (32%, n = 105) and obstructive CAD (27%, n = 88). When present, ETT features (i.e., angina, DTS, ischaemic electrocardiogram changes, and exercise capacity) individually failed to predict CV death/MI after adjustment for Morise score. Conversely, both obstructive CAD [HR 4.9 (1.0-23.3), P = 0.048] and CAD extent by segment involvement score >4 [HR 3.9 (1.0-15.2), P = 0.049] predicted increased risk for CV death or MI. Patients with a low-risk ETT have an excellent prognosis at 40 months, despite the frequent presence of non-obstructive (32%) and obstructive (27%) CAD. In patients with an intermediate- to high-risk ETT (DTS <5), CTA can provide incremental risk stratification for future CV events.