530Myocardial fibrosis affects left ventricular contractile reserve: noninvasive assessment by cardiac magnetic resonance and stress echo

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Background: Fibrosis is a common endpoint of many pathological processes affecting the myocardium, influences regional and global left ventricular (LV) function and can be accurately measured with late post-gadolinium myocardial enhancement (LGE) cardiac magnetic resonance.Aim: To assess the value of resting function and contractile reserve evaluated by stress echocardiography in predicting myocardial fibrosis. Methods. We studied 42 patients (32 men; 63±12 years) with idiopathic (n=21) or ischemic (n=21) dilated cardiomyopathy (EF <40% by selection). They underwent, on separate days and within 1 week, stress echo with exercise (n=13), dobutamine (n=28, up to 40 mcg/kg) or dipyridamole (n=1, up to 0.86 mg/kg). By selection, no patient had inducible ischemia with stress echo. We measured LV ejection fraction (EF, Simpson method) and wall motion score index (WMSI) by 2D-echo at rest and peak stress. LGE was semiauthomatically quantified and expressed as left ventricular mass percentage (LGE%).Results: Resting Ejection was 29±7%. LGE score was 13.6±18.2 (range 0-60). WMSI was 2.1±0.3 at rest and 1.9±0.4 at peak stress (p<.0001). LGE was correlated with peak WMSI (r=.6, p<0.01, see figure) and - more weakly - with resting WMSI (r=.47, p=.009), whereas no correlation was detected with resting EF (r=.2, p=ns) or peak EF (r=.1, p=ns).Conclusion: Severity of myocardial fibrosis by LGE correlates with contractile reserve during stress echo in a broad range of myocardial fibrosis in patients with ischemic and non-ischemic dilated cardiomyopathy.

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