Influence of myocardial fibrosis on left ventricular diastolic function: noninvasive assessment by cardiac magnetic resonance and echo.

BACKGROUND: Fibrosis is a common end point of many pathological processes affecting the myocardium and may alter myocardial relaxation properties. By measuring myocardial fibrosis with cardiac magnetic resonance and diastolic function with Doppler echocardiography, we sought to define the influence of fibrosis on left ventricular diastolic function. METHODS AND
RESULTS: Two hundred four eligible subjects from 252 consecutive subjects undergoing late postgadolinium myocardial enhancement (LGE) cardiac magnetic resonance and Doppler echocardiography were investigated. Subjects with normal diastolic function exhibited no or minimal fibrosis (median LGE score, 0; interquartile range, 0 to 0). In contrast, the majority of patients with cardiomyopathy (regardless of underlying cause) had abnormal diastolic function indices and substantial fibrosis (median LGE score, 3; interquartile range, 0 to 6.25). Prevalence of LGE positivity by diastolic filling pattern was 13% in normal, 48% in impaired relaxation, 78% in pseudonormal, and 87% in restrictive filling (P<0.0001). Similarly, LGE score was significantly higher in patients with deceleration time <150 ms (P<0.012), and it progressively increased with increasing left ventricular filling pressure estimated by tissue Doppler imaging-derived E/E' (P<0.0001). After multivariate analysis, LGE remained significantly correlated with degree of diastolic dysfunction (P=0.0001).
CONCLUSIONS: Severity of myocardial fibrosis by LGE significantly correlates with the degree of diastolic dysfunction in a broad range of cardiac conditions. Noninvasive assessment of myocardial fibrosis may provide valuable insights into the pathophysiology of left ventricular diastolic function and therapeutic response.