Coronary flow reserve in hypertrophic cardiomyopathy: relation with microvascular dysfunction and pathophysiological characteristics

Abstract

BACKGROUND.: The decrease in coronary flow reserve (CFR) in hypertrophic cardiomyopathy (HCM) predisposes to myocardial ischaemia, systolic dysfunction and cardiac death. In this study we investigate to which extent haemodynamic, echocardiographic, and histological parameters contribute to the reduction of CFR. METHODS.: In ten HCM patients (mean age 44+/-14 years) and eight heart transplant (HTX) patients (mean age 51+/-6 years) CFR was calculated in the left anterior descending coronary artery. In all subjects haemodynamic, echocardiographic and histological parameters were assessed. The relationship between these variables and CFR was determined using linear regression analysis. RESULTS.: CFR was reduced in HCM compared with HTX patients (1.6+/-0.7 vs. 2.7+/-0.8, p<0.01). An increase in septal thickness (p<0.005), indexed left ventricular (LV) mass (p<0.005), LV end-diastolic pressure (p<0.001), LV outflow tract gradient (p<0.05) and a decrease in arteriolar lumen size (p<0.05) were all related to a reduction in CFR. CONCLUSION.: In HCM patients haemodynamic (LV end-diastolic pressure, LV outflow tract gradient), echocardiographic (indexed LV mass) and histological (% luminal area of the arterioles) changes are responsible for a decrease in CFR. (Neth Heart J 2007;15:209-15.).

Figure 1

The capillary density of a victim of a car accident is represented in the upper panel. In the lower panel, the capillary density of a patient with hypertrophic cardiomyopathy is displayed. Note the decrease in the number of capillary vessels in hypertrophic cardiomyopathy (magnification 40 x).

Figure 2A

The relation between the coronary flow reserve (CFR) and left ventricular mass corrected for body surface area (LV mass/BSA, g/m²) in patients with hypertrophic cardiomyopathy (⋄) and cardiac transplant recipients (◼).

Figure 2B

The relation between the coronary flow reserve (CFR) and left ventricular end-diastolic pressure (LVEDP, mmHg) in patients with hypertrophic cardiomyopathy (⋄) and cardiac transplant recipients (◼).

Figure 3

Mechanisms underlying the reduction in coronary flow reserve in hypertrophic cardiomyopathy. LVOT=left ventricular outflow tract, LVEDP=LV end-diastolic pressure, CFR=coronary flow reserve.