Elevated Resting Coronary Blood Flow Is Associated With Death, MI, and HF in All-Comer Patients With Chronic Coronary Syndrome.

BACKGROUND

The prognostic implications of bolus thermodilution-derived resting coronary blood flow in all-comer patients with chronic coronary syndrome are not known. We investigated the association of thermodilution-derived indices characterizing coronary flow with outcomes.

METHODS

Patients with chronic coronary syndrome with and without obstructive coronary artery disease were included before undergoing coronary angiography in this prospective observational study. Measurements of the index of microcirculatory resistance, baseline resistance index, resting coronary blood flow (CBF), and hyperemic CBF were obtained with thermodilution in the left anterior descending coronary artery. Cox-regression analyses adjusted for age, sex, number of diseased vessels, and estimated creatinine clearance, as well as Kaplan-Meier plots, were used to evaluate the relation between flow indices and the primary composite outcome of all-cause mortality, nonfatal myocardial infarction, or heart failure hospitalization.

RESULTS

Analyses included 410 patients with 55 events. Median follow-up was 5.4 years. Resting CBF was independently associated with the primary outcome (hazard ratio, 1.23 [95% CI 1.02-1.48]). Resting CBF was associated with the primary outcome in patients undergoing revascularization (hazard ratio, 1.30 [95% CI 1.04-1.64]) but not in patients not undergoing revascularization (hazard ratio, 1.15 [95% 0.82-1.60]; P interaction=0.771). Neither the index of microcirculatory resistance nor hyperemic CBF were associated with outcomes. Functional coronary microvascular dysfunction was associated with a higher incidence of death and nonfatal myocardial infarction versus no coronary microvascular dysfunction (log-rank P=0.041), whereas structural coronary microvascular dysfunction was not.

CONCLUSIONS

Elevated resting CBF in the left anterior descending coronary artery was associated with major adverse cardiovascular events in chronic coronary syndrome, whereas hyperemic microcirculatory resistance and flow were not.

REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT06306066.