Endocardial versus midwall measurement of left ventricular function in mild hypertension: an insight from the Harvest Study

Abstract

Objective: To compare endocardial and midwall measurement of left ventricular fractional shortening in assessing cardiac systolic function in hypertension.

Setting: Seventeen hypertension clinics in northeast Italy.

Main outcome measures: Left ventricular endocardial fractional shorteningcircumferential stress relationship versus midwall shortening-stress relationship in the subjects divided according to relative wall thickness (RWT) and left ventricular mass indexed by body surface area.

Patients: Borderline-to-mild hypertensives [n = 635, aged 33 +/- 0.3 years (mean +/- SEM), office blood pressure 146 +/- 0.4/94 +/- 0.2 mmHg (means +/- SEM)] in the Harvest Study and 50 normotensive controls with similar age and sex distributions.

Methods: Blood pressure was measured by 24 h ambulatory monitoring. Left ventricular dimensional and functional indices were assessed by M-mode echocardiography.

Results: In the subjects divided into quintiles of RWT, the left ventricular shortening-stress relationship was increased in a parallel fashion when calculated by endocardial and by midwall measurements for RWT < or = 0.35. Instead, for greater RWT values (> or = 0.37) endocardial measurement constantly gave large values than did midwall measurement. Both the endocardial and the midwall shortening-stress relationships progressively decreased with increasing RWT. However, the endocardial shortening-stress relationship remained greater than normal at any RWT, whereas the midwall shortening-stress relationship was decreased for RWT > or = 0.37. In a multiple-regression analysis RWT was the most potent predictor of the endocardialmidwall shortening difference, left ventricular mass and 24 h systolic blood pressure being the second and third most potent predictors.

Conclusions: We found a parallel increase in indices of cavity emptying and of myocardial contractility in mild hypertensive subjects with normal left ventricular geometry. When the RWT is increased, ejection phase indices may be normal in the presence of decreased myocardial contractility.