Dipyridamole-Induced Ischemia as a Prognostic Marker of Future Adverse Cardiac Events in Adult Patients With Hypertrophic Cardiomyopathy

Abstract

Background Myocardial ischemia may play a role in the natural history of hypertrophic cardiomyopathy (HCM). To assess the relative prevalence and the prognostic value of dipyridamole-induced ischemia, 79 patients with HCM and without concomitant coronary artery disease (53 men; mean age, 46±15 years) underwent a high-dose (up to 0.84 mg/kg over 10 minutes) dipyridamole test with 12-lead ECG and two-dimensional echo monitoring and were followed up for a mean of 6 years. Methods and Results Twenty-nine patients (37%) showed ECG (ie, ST depression ≥2 mV) signs of myocardial ischemia during dipyridamole test (group 1), whereas 50 (63%) had a negative test (group 2). No patient had transient wall motion abnormalities during the dipyridamole test. During the follow-up, 16 events (ie, left ventricular or atrial enlargement, unstable angina, syncope, atrial fibrillation, and bundle-branch block) occurred in 29 patients in group 1 and 5 in 50 patients in group 2 (55% versus 10%, P <.001). Patients with a positive dipyridamole test showed worse 72-month event-free survival rates compared with patients with a negative test (36.2% versus 84.2%, P <.001). A forward stepwise event-free survival analysis identified dipyridamole test positivity by ECG criteria (χ 2 =19.7, P =.0001), rest gradient (χ 2 =11.3, P =.0008), and age (χ 2 =4.1; P =.0413) as independent and additive predictors of subsequent events. Conclusions ECG signs of myocardial ischemia elicited by dipyridamole are frequent in patients with HCM and identify patients at higher risk of cardiac events, suggesting a potentially important pathogenetic role of inducible myocardial ischemia in determining adverse cardiac events in these patients.