Left bundle branch block in chronic heart failure-impact on diastolic function, filling pressures, and B-type natriuretic peptide levels.

BACKGROUND: For patients with chronic heart failure (CHF), left bundle branch block (LBBB) is associated with impaired systolic function and increased morbidity and mortality, but data on diastolic function are scarce. In this patient population, we attempted to define the impact of LBBB on diastolic function, filling pressures, and brain natriuretic peptide and its circulating N-terminal precursor (NT-proBNP) levels.
METHODS: A total of 94 patients with stable CHF (48 with complete LBBB, 46 without intraventricular conduction delay and normal QRS duration) underwent conventional 2-dimensional/Doppler echocardiography and Doppler tissue analysis of mitral annular velocities. As a measure of left ventricular filling pressures, the ratio of peak early mitral flow velocity to peak early diastolic mitral annular velocity was derived. NT-proBNP measurements were carried out on a bench-top analyzer (Elecsys-2010, Roche Diagnostics, Mannheim, Germany).
RESULTS: Patients with or without LBBB did not differ with respect to the cause of CHF or ejection fraction, but in LBBB deceleration time was shorter (163 +/- 66 vs 205 +/- 95 milliseconds, P = .021) and a restrictive mitral filling pattern was more frequent (35% vs 11%, P = .005). In such patients, the ratio of peak early mitral flow velocity to peak early diastolic mitral annular velocity was higher (14.5 +/- 6.2 vs 10.6 +/- 5.2, P < .001) and NT-proBNP was elevated (3553 +/- 3725 vs 850 +/- 896 pg/mL, P < .01) as compared with patients without LBBB.
CONCLUSION: For patients with CHF and comparable systolic performance, LBBB is associated with more severe diastolic dysfunction, elevated filling pressures, and higher NT-proBNP levels. These findings may contribute to increased morbidity and mortality of such patients.