Abstract 13461: Passive Myocardial Tension in Patients With Hypertension, Type 2 Diabetes Mellitus and Coronary Artery Disease
Both hypertension (HTN) and type 2 diabetes mellitus (DM) are known to cause left ventricular (LV) diastolic dysfunction based on non-invasive estimates. However, it is unclear which myocardial determinants of diastolic function are affected by these conditions. In the present study we tested the hypothesis that diagnosed HTN and HTN combined with DM (HTN+DM) increase passive myocardial tension (PMT), an important determinant of LV diastolic function. PMT was measured over a range of sarcomere lengths (SLs) from 2.0-2.6 μM in demembranated myocardial strips obtained by epicardial biopsy from patients (pts) with coronary artery disease (CAD) undergoing bypass grafting. All pts had normal LV ejection fraction and wall motion. HTN was diagnosed based on a clinical history and prescription of blood pressure lowering drugs. CAD pts without HTN or DM served as controls. The current analysis is restricted to the male pts, with analysis of females pending. In pts with HTN (n=13) the relation between SL and PMT was significantly elevated compared with controls (n=20; p = .02). Thus, for example, at SL 2.6 μM PMT was 11.7 ± 2.2 (±SE) mN/mm2 in HTN vs 8.0 ± 1.2 mN/mm2 in controls. A similar average increase in PMT was observed in pts with HTN+DM (n=13), but this did not achieve statistical significance. In HTN patients, PMT was not significantly correlated with LV mass index, left atrial volume or E/E’. Moreover, PMT was similar in HTN patients with (n=6) and without (n=6) LV hypertrophy. We conclude that diagnosed HTN is associated with increased PMT in male pts with CAD. LV hypertrophy is not a requirement for increased PMT and PMT is not predictive of clinical indexes of diastolic function. These results suggest that other functional abnormalities, i.e., calcium handling and/or myofilament properties, also contribute significantly to altered LV diastolic function in HTN. Surprisingly, coexistent DM was not associated with additional increments in PMT.
- © 2011 by American Heart Association, Inc.