Using digital subtraction coronary angiography (DSA), we evaluated the regional myocardial coronary blood flow reserve (rMFR) in 18 patients with hypertrophic cardiomyopathy (HCM). There were 13 patients with asymmetrical septal hypertrophy (ASH), and 5 with asymmetrical apical hypertrophy (AAH). Eight subjects without apparent cardiac abnormality served as controls. Relations between the rMFR and regional wall thickness as determined by echocardiography were also investigated. Peak contrast density (Cm) and time to Cm (Tm) were measured from digital angiograms at the middle and distal ventricular septum (VS) and at the apical and left ventricular posterior wall (PW). The rMFR of each region of interest was expressed as the ratio of Cm/Tm at the baseline and at peak hyperemic response induced by intracoronary administration of papaverine. The rMFR was significantly lower at the VS and apex in HCM than in controls: middle VS, 1.9 +/- 0.5 vs 3.9 +/- 0.5, p0.001; distal VS, 2.0 +/- 0.5 vs 4.4 +/- 0.9, p0.001; and the apex, 2.0 +/- 0.7 vs 4.5 +/- 1.6, p0.01. However, it did not differ at the PW; 2.6 +/- 0.9 vs 3.0 +/- 0.9 between the 3 groups. The middle VS and apex, where the wall was the thickest, had the lowest rMFR in ASH and AAH. Furthermore, at the VS and apex, a curvilinear relationship was observed between the rMFR and wall thickness (rMFR = -0.88 in WT + 2.39, r = -0.57, p0.02).(ABSTRACT TRUNCATED AT 250 WORDS)