Left ventricular function and contractile reserve in patients with hypertension.

Abstract

An impaired contractile reserve (CR) may be an early manifestation of left ventricular (LV) systolic dysfunction in hypertensive patients. Using normotensive patients as controls, we examined LV CR and its correlates in hypertensive patients. One hundred and twenty-nine (68 men, aged 58.6 ± 9.5 years, 73 had hypertension) patients underwent dobutamine echocardiography. Patients with significant coronary or valvular disease, previous myocardial infarction or revascularization, and diabetes were excluded. LV ejection fraction (LVEF), global longitudinal strain (GLS), circumferential, and radial strain were measured at rest and at low-dose dobutamine. Absolute CR was calculated as the difference in LVEF and multi-directional strain between low-dose dobutamine and their corresponding resting values. Relative CR is the ratio of absolute CR to their corresponding resting values. Hypertensive patients, compared with controls, have significantly impaired GLS at rest (-16.8 ± 2.2% vs. -19.6 ± 1.5%, P < 0.0001) and at low-dose dobutamine (-17.9 ± 2.7% vs. -22.8 ± 2.6%, P < 0.0001). Absolute and relative GLS CR were significantly lower in hypertensive patients (-1.1 ± 2.1% vs. -3.2 ± 2.2% and 7.4 ± 13.9% vs. 16.4 ± 11.7%, respectively, both P < 0.001). Circumferential strain was preserved at rest but impaired at low-dose dobutamine in hypertensive patients (-23.0 ± 4.1% vs. -25.2 ± 3.4%, P = 0.002). There were no differences in LVEF or radial strain between the groups. LV wall thickness and systolic blood pressure correlated significantly with GLS at rest and at low-dose dobutamine. LV wall thickness is the only independent correlates of absolute CR. Compared with controls, hypertensive patients have impaired LV GLS at rest and impaired CR despite normal LVEF. Impaired CR correlated with LV wall thickness but independent of prevailing blood pressure.