Aims: Coronary flow-reserve (CFR) can be impaired in non-ischaemic dilated cardiomyopathy (DCM), unmasking a coronary microcirculatory dysfunction of potential prognostic impact. The aim of the present study is to evaluate the prognostic value of Doppler echocardiographic-derived CFR in patients with DCM.
Methods and results: We evaluated 129 DCM patients (85 male; age 62+/-11) by transthoracic dipyridamole (0.84 mg/kg in 10 min) stress echocardiography. All patients had an ejection fraction<40% (mean 32+/-7) and angiographically normal coronary arteries with NYHA class<or=3. CFR was assessed on left anterior descending artery using pulsed Doppler as the ratio of maximal peak vasodilation (dipyridamole) to rest diastolic flow velocity. All patients were followed-up for a median of 22 months. Mean CFR was 2.0+/-0.5. At individual patient analysis 46 patients had normal (CFR>2.0) and 83 had abnormal CFR. During follow-up, 18 patients died and 33 showed worsening of NYHA class. The worse event-free survival was observed in those patients with an abnormal CFR when compared with those having a normal CFR at high dose of dipyridamole (70 vs. 22%, at 75 months of follow-up, P<0.0001). In the multivariable analysis, severity of mitral insufficiency (HR=1.9, 95% CI=1.06-2.87), abnormal CFR (HR=4.0, 95% CI=1.1-15.6), resting wall motion score index (HR=6.9, 95% CI=1.5-30.7) were independent predictors of survival.
Conclusion: In DCM patients, CFR is often impaired. A reduced CFR during vasodilator stress is an independent prognostic marker of bad prognosis.