Intrinsic cardiac elastography in patients with primary mitral regurgitation: predictive role after mitral valve repair.

Abstract

Chronic volume-overload can impair systolic and diastolic myocardial properties. We tested the hypothesis that Intrinsic Cardiac Elastography may detect alterations in passive myocardial elasticity in patients with chronic severe mitral regurgitation (MR) and predict worsening left ventricular (LV) function after mitral valve repair (MVr). Comprehensive transthoracic echocardiography and cardiac elastography were performed in 80 patients with primary MR (prolapse and/or flail leaflets) of varying severity and compared with 40 normal subjects. In patients who underwent MVr (n = 51), elastography measurements were related to changes in left ventricular ejection fraction (LVEF) at short-term (3-4 days post-op) and mid-term (1year) follow-up. Most patients were asymptomatic or mildly symptomatic and had preserved LVEF (>60%). Intrinsic velocity propagation (iVP) of myocardial stretch, a direct measure of myocardial stiffness, was higher in patients with severe MR {median 2.0 [interquartile range (IQR) 1.5-2.2] m/s, range 1.1-3.4 m/s; n = 56} compared to normal subjects [median 1.7 (IQR 1.5-1.8) m/s; n = 40; P = 0.0005], but not in those with mild or moderate MR [median 1.7 (IQR 1.4-1.9) m/s; n = 24]. A higher iVP was associated with more severe LV volume-overload and LV and left atrial enlargement (P < 0.05 for all). In patients undergoing MVr, a higher iVP independently predicted a larger drop in LVEF post-intervention (short-term, P = 0.001; 1 year, P = 0.007), incrementally to pre-operative LVEF (P < 0.05). Non-invasive measurements of myocardial stiffness were able to predict functional deterioration after MVr for chronic primary MR. Further studies should investigate the mechanisms and practical utility of this novel measurement.