Cardiac size, autonomic function, and 5-year follow-up of chronic heart failure patients with severe prolongation of ventricular activation.

BACKGROUND

Chronic heart failure is characterized by left ventricular dilation and abnormalities of cardiac autonomic function. Up to 20% of patients with chronic heart failure have QRS prolongation, which can lead to asynchronous left ventricular contraction. We tested the hypotheses that in patients with chronic heart failure, QRS > 150 ms is a risk factor for additional abnormalities of ventricular morphology, heart rate variability, and increased mortality.

METHODS AND RESULTS

In 184 patients with left ventricular ejection fraction < 35%, QRS duration was > 150 ms in 53, and </= 150 ms in 131. We evaluated patients with baseline chest radiographs, echocardiograms, and Holter recordings. Patients with QRS duration above and below 150 ms were similar in age, sex, functional class, renal function, serum sodium, and ejection fraction. In patients with QRS > 150 ms, left ventricular end-diastolic and end-systolic diameters were greater than patients with QRS duration </=150 ms (P <.01). Patients with QRS > 150 ms had less low frequency R-R interval spectral power (P <.04). At 5 years 60% of patients with QRS > 150 ms had died compared with 35% of patients with QRS </=150 ms (P <.001). This increase in mortality was predominantly the result of an increase in progressive heart failure.

CONCLUSIONS

Chronic heart failure patients with QRS duration > 150 ms have exaggerated disturbance of cardiac autonomic function, and left ventricular remodeling and significantly higher mortality than patients with QRS duration </= 150 ms.