Prognostic Value of Left and Right Coronary Flow Reserve Assessment in Nonischemic Dilated Cardiomyopathy by Transthoracic Doppler Echocardiography

Background: Coronary flow reserve (CFR) in the left anterior descending artery (LAD) can be reduced in nonischemic dilated cardiomyopathy (DCM). The aim of this study was to assess the prognostic value of CFR in LAD and in the posterior descending artery (PD) in DCM patients. Methods: Seventy-two DCM patients (44 men, mean age 64 6 13 years) underwent dipyridamole (0.84 mg/kg in 6 minutes) stress echo. CFR was defined as the ratio between maximal vasodilation and rest peak diastolic flow velocity in LAD and PD. Results: CFR was abnormal in LAD in 42 out of 72 patients and in PD in 31 out of 55. All patients completed the clinical follow-up, and 56 patients completed the echocardiographic follow-up. During median follow-up of 42 months, 33 events (7 deaths, 26 major cardiac events) occurred. Event rate was markedly higher for patients with reduced CFR compared with DCM patients with normal CRF in LAD (0 vs 19 events; P!.001) and in PD (1 vs 13 events; P!.001). CFR in LAD and in PD were significantly related to the change in end-systolic volume during follow-up (r 5 0.481, P!.001; and r 5 0.407, P 5 .028; respectively). Preserved CFR in both LAD and PD was associated with better (P ! .0001) event-free survival compared with abnormal CFR (log rank: 28.1; P ! .0001). Conclusions: In DCM patients, impairment of CFR in LAD and PD is related to a worse outcome; CFR impairment is more relevant when it occurs in LAD. PD evaluation may be redundant and time-consuming, because the additive value is small and the feasibility suboptimal.