Dipyridamole-induced ischemia as a prognostic marker of future adverse cardiac events in adult patients with hypertrophic cardiomyopathy. Echo Persantine Italian Cooperative (EPIC) Study Group, Subproject Hypertrophic Cardiomyopathy.

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 > or = 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 (chi2=19.7, P=.0001), rest gradient (chi2=11.3, P=.0008), and age (chi2=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.