Dipyridamole stress echocardiography stratifies outcomes of asymptomatic patients with recent myocardial revascularization.

BACKGROUND: Patients with previous myocardial revascularization, even if symptom-free, remain at risk of subsequent cardiac events, so that a non-invasive tool able to stratify this population is wishful.
OBJECTIVES: To assess the prognostic value of dipyridamole stress echocardiography (DipSE) in a population of asymptomatic patients following complete myocardial revascularization, either by coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI).
METHODS: We retrospectively evaluated 104 consecutive symptom-free patients (mean age 67+/-9.3 years, 75 males) with recent (<12 months) complete myocardial revascularization (48% PCI, 52% CABG) undergoing DipSE. Ischemia was defined as the onset of a new or worsening wall motion abnormality during DipSE. The composite end point of the study was cardiac death and non-fatal acute coronary syndrome.
RESULTS: Myocardial ischemia was identified in 23 patients (22.1%). During a mean follow up of 21 months, 7 (30.4%) out of these patients suffered cardiac events. Among the remaining 81 patients (77.9%) with negative DipSE results, 7 (8.6%) experienced cardiac events. At multivariable analysis only a positive DipSE (odds ratio 3.9, P=0.03), wall motion score index at peak of stress (OR 3.6, P=0.04) and a prior myocardial infarction (odds ratio 3.5, P=0.04) achieved statistical significance for cardiac events. Moreover, DipSE effectively stratified patients into a high and low risk group according to presence of inducible ischemia (event rate per year 16% vs 4.8%, P=0.02).
CONCLUSIONS: DipSE yields appropriate risk stratification and provides incremental prognostic value over clinical variables even in asymptomatic patients with prior complete myocardial revascularization. A negative DipSE portends a benign prognosis (<5% event rate/year) in such population.