Resting coronary flow and long-term clinical outcomes in dilated cardiomyopathy.

Compensatory high resting coronary flow (rCF) is a major determinant of low coronary flow reserve in patients with dilated cardiomyopathy (DCM). We sought to assess if angiography-derived rCF was associated with left ventricle reverse remodeling (LVRR) and clinical outcomes in DCM. Angiography-derived rCF was derived based on TIMI frame count and validated using invasive continuous thermodilution absolute flow (n = 48). The association between rCF and clinical outcomes was evaluated in a prospectively enrolled cohort of patients with DCM who underwent coronary angiography to rule out coronary disease (n = 110). The primary endpoint was the composite of all-cause death, rehospitalization for heart failure, relevant ventricular arrhythmias, appropriate implanted cardiac defibrillator intervention, and cardiac transplantation or left ventricular assist device implantation. LVRR was evaluated after at least 12 months of guidelines-directed medical therapy (GDMT). rCF was significantly correlated with thermodilution-derived resting coronary perfusion (rho = 0.411, p = 0.004). High rCF (≥ 2.32) was associated with impaired microvascular resistance reserve (AUC 0.721; 95% CI 0.572 to 0.870, p = 0.004). Among 110 patients of the prognostic cohort, 15 patients (13.6%) met the primary endpoint. rCF was higher in patients without LVRR (2.14 [1.67 to 3.0] vs. 1.87 [1.36 to 2.50], p = 0.036) and in those who met the primary endpoint (3.0 [1.87 to 3.75] vs. 1.87 [1.36 to 2.50], p = 0.004). Patients with rCF ≥ 2.32 had a higher rate of events compared with patients with preserved rCF (27.5% vs. 5.7%, log-rank p = 0.007; aHR 4.143 [95% CI 1.315 to 13.059], p = 0.015). In DCM patients, high rCF was associated with a reduced rate of LVRR after GDMT and adverse clinical outcomes at long-term follow-up.