Impact of myocardial diastolic dysfunction on coronary flow reserve in hypertensive patients with left ventricular hypertrophy.

ABSTRACT

BACKGROUND: The aim of the study was to assess the possible association, in hypertensive patients, between left ventricular myocardial diastolic dysfunction and coronary flow reserve (CFR) in relation to the presence of left ventricular hypertrophy (LVH). METHODS: Twenty-eight untreated hypertensives (22 males, 6 females, mean age 53.1 years), free of coronary artery disease, were enrolled in the study. Standard Doppler echocardiography, color Doppler tissue imaging of the posterior septum during dobutamine stress and second harmonic Doppler of the distal left anterior descending coronary vessel, at baseline and after maximal hyperemia induced by dipyridamole, were performed. CFR was estimated as the ratio between hyperemic and baseline diastolic velocities. Hypertensives were divided into two groups according to the left ventricular mass index 15 without LVH (left ventricular mass index < 51 g/m2.7) and 13 with LVH (left ventricular mass index > 51 g/m2.7). The two groups were comparable for sex prevalence, age, body mass index, baseline heart rate and blood pressure. RESULTS: Color Doppler tissue imaging did not show any significant difference of both the baseline and high-dobutamine septal systolic peak velocities between the two groups. The ratio between myocardial early and atrial peak velocities (Em/Am ratio) was lower in patients with LVH, either at baseline (p < 0.01) or at high-dose dobutamine (p < 0.0001). Also, CFR was lower in the presence of LVH (p < 0.01). After adjusting for age, body mass index, left ventricular mass index, diastolic blood pressure and high-dose dobutamine heart rate by a multiple linear regression analysis, the high-dose dobutamine Em/Am ratio was an independent contributor of CFR in the overall hypertensive population (beta = 0.65, p < 0.0001) (cumulative r2 = 0.38, p < 0.0001). CONCLUSIONS: The combined use of second harmonic Doppler and color Doppler tissue imaging identifies, in arterial hypertension, an association between myocardial diastolic properties and CFR, independent of the presence of LVH. In hypertensive patients free of coronary artery stenosis, left ventricular myocardial diastolic dysfunction may be a determinant in the impairment of the coronary microvessel vasodilation capacity or a marker of silent ischemia involving the microvascular circulation.