Depressed myocardial energetic efficiency is associated with increased cardiovascular risk in hypertensive left ventricular hypertrophy

Abstract

Myocardial mechano-energetic efficiency (MEE) can be easily approximated by the ratio of stroke work [i.e. SBP times stroke volume (SV)] to a rough estimate of energy consumption, the 'double product' [SBP times heart rate (HR)], which can be simplified as SV/HR. We evaluated whether MEE is associated with adverse prognosis in relation to the presence of left ventricular hypertrophy (LVH). Hypertensive participants of the Campania Salute Network (n = 12 353) without prevalent coronary or cerebrovascular disease and with ejection fraction more than 50% were cross-sectionally and longitudinally analyzed, over a median follow-up of 31 months. MEE was estimated by echocardiographic SV (z-derived)/(HR × 0.6). Due to the close relation with left ventricular mass (LVM) (P < 0.0001), MEE was normalized for LVM (MEEi) and divided into quartiles. The lowest quartile of MEEi (<0.29 ml/s per g) was considered 'low MEEi'. MEEi was greater in women than in men (P < 0.0001). Progressively lower MEEi was associated with older age, male sex, obesity, diabetes, LVH, concentric geometry, inappropriate LVM and diastolic dysfunction, more use of antihypertensive therapy, and higher BP (all P < 0.002). In Cox regression, after controlling for LVH, age, sex, and average follow-up SBP, low MEEi exhibited increased hazard of composite fatal and nonfatal cardiovascular end-points (P < 0.01), independently of antihypertensive therapy and associated cardiovascular risk factors. A simple estimate of low myocardial mechano-energetic efficiency is associated with altered metabolic profile, LVH, concentric left ventricular geometry, and diastolic dysfunction and predicts cardiovascular end-points, independently of age, sex, LVH antihypertensive therapy, and cardiovascular risk factors.