Background: Reduced coronary flow reserve (CFR) in hypercholesterolemic patients without evidence of ischemia has been reported. However, it remains uncertain whether this abnormality occurs without overt coronary atherosclerosis. This study aimed to clarify whether CFR is impaired even in anatomically normal coronary arteries in hypercholesterolemic patients and to compare CFR between familial hypercholesterolemic (FH) patients and secondary hypercholesterolemic (SH) patients.
Methods and results: Twenty-two patients with hypercholesterolemia (11 FH, 11 SH) and 11 control subjects were studied. Baseline myocardial blood flow (MBF) and MBF during dipyridamole loading were measured in segments perfused by angiographically normal coronary arteries with the use of positron emission tomography and 13N-ammonia, and CFR was calculated. Baseline MBF (mL/min per 100 g heart wt) in FH (81.3 +/- 31.4) and SH (70.0 +/- 20.7) patients was not different from that in control subjects (75.0 +/- 34.9). However, MBF during dipyridamole loading was significantly lower in FH patients (129 +/- 19.1) than in control subjects (322 +/- 174, P < .01) and SH patients (210 +/- 71.2, P < .01). CFR in FH patients (1.59 +/- 0.41) was also significantly lower compared with both control subjects (4.22 +/- 1.42, P < .01) and SH patients (3.00 +/- 0.96, P < .01). CFR in SH patients was also significantly lower than that in control subjects (P < .05). CFR correlated significantly with both plasma total cholesterol (r = .67, P < .01) and LDL cholesterol concentrations (r = .69, P < .01).
Conclusions: CFR was decreased even in anatomically normal coronary arteries in hypercholesterolemic patients. This abnormality was more prominent in FH patients.