Insulin resistance-related differences in the relationship between left ventricular hypertrophy and cardiorespiratory fitness in hypertensive Black sub-Saharan Africans.

BACKGROUND

Left ventricular hypertrophy (LVH) is associated with impaired cardiorespiratory fitness (CRF), a surrogate marker of poor outcome. Insulin resistance (IR) plays a central role in all stages of cardiovascular disease continuum. This study evaluates IR-related differences in the relationship between left ventricular mass (LVM) and CRF in asymptomatic newly diagnosed hypertensive Black sub-Saharan Africans.

METHODS

In this cross-sectional observational study, 126 asymptomatic newly diagnosed hypertensive participants (50.5 ± 9.5 years) underwent comprehensive resting transthoracic echocardiographic examination and maximal incremental cardiopulmonary exercise test (CPET). CRF was estimated in maximal oxygen uptake (VO2max). CPET results were compared between participants with and without LVH. Multivariate analysis examined the influence of IR on the observed differences.

RESULTS

Those with LVH had lower VO2max (15.7 ± 5.5 mL min kg vs. 18.4 ± 3.7 mL min kg; = 0.001) than those without LVH. In patients with IR, LVM ( = -0.261, = 0.012), LVM indexed to body surface area (LVMIbsa; = -0.229, = 0.027), and LVM indexed to height to an allometric power of 2.7 (LVMIh; = -0.351, = 0.001), and VO2max were negatively correlated. In hypertensive patients without IR, these same parameters and VO2max have no significant correlation. Body mass index (BMI), LVM, and LVMIbsa emerged as independent determinants of VO2max, explaining 46.9% of its variability (overall = 0.001) in IR participants, a relationship not found in participants without IR.

CONCLUSIONS

IR may participate in the deterioration of CRF associated with LVH. Measures to improve insulin sensitivity should be considered for improving CRF and therefore the prognosis of insulin-resistant hypertensive patients. Targeting IR in hypertensive patients with LVH could improve prognosis.