Matching between regional coronary vasodilator capacity and corresponding circumferential strain in individuals with normal and increasing body weight

Background. To define the relationship between regional coronary vasodilator capacity and myocardial circumferential strain at rest in normal weight, overweight, and obese individuals with normal global left-ventricular function. Methods and Results. Myocardial blood flow at rest and during pharmacologic vasodilation was measured with 13N-ammonia PET/CT in mL/g/minute in normal weight control (CON, n = 12), overweight (OW, n = 10), and obese individuals (OB, n = 10). In addition, resting myocardial function was evaluated as circumferential strain (εc, %) by MRI. Global myocardial flow reserve (MFR) did not differ significantly between CON and OW (2.98 ± 0.96 vs 2.70 ± 0.66, P = .290), whereas it declined significantly in OB (1.98 ± 1.04, P = .030). Further, global εc (%) was comparable between CON, OW, and OB (20.24 ± 0.03, 20.23 ± 0.02, and 20.23 ± 0.04) but it was lowest in OB when normalized to the rate-pressure product (N εc: 20.31 ± 0.06, 20.32 ± 0.05, and 20.26 ± 0.08). When MFR of the three major coronary territories was correlated with corresponding εc, a positive association was observed in CON (r = 0.36, P = .030), in OW (r = 0.54, P = .002), and also in OB when relating N εc to coronary vascular resistance during pharmacologic vasodilation (r = 20.46, P = .010). Conclusions. Higher coronary vasodilator capacity is related to corresponding regional circumferential strain at rest in non-obese individuals, while this is also observed for reduced MFR in obesity.