A pilot study evaluating daily physical activity before and after cardiac resynchronization therapy.

Benefits of daily physical activity are well known, but there are limited data to describe physical activity in heart failure patients who receive cardiac resynchronization therapy devices. The purpose of this pilot study was to evaluate changes in physical activity (PA) levels before and 3 months after Cardiac Resynchronization Therapy (CRT) and determine relationships of PA to physical function and comorbidities, as well as describe changes in heart failure symptoms. This was a prospective pre-/post- design that included a convenience sample of 21 subjects using self- report questionnaires and 6-minute walk test (6MWT). In this sample, there was a 2.6 hour increase in high level PA (p = 0.024). 6MW distance improved 27% (p < .0001). Subjects experienced a 25% reduction in dyspnea (p = 0.015). Knowledge gained from this study adds to the understanding of the patient response to CRT. Further study is recommended to generalize findings and explore whether an intervention (cardiac rehabilitation) is indicated.

Cardiac resynchronization pacing therapy.

Approximately one third of patients with congestive heart failure and systolic dysfunction have an intraventricular conduction delay that is manifested as a QRS duration >120 ms. An intraventricular conduction delay adversely affects ventricular performance by causing dyssynchrony in ventricular activation. When ventricular dyssynchrony is present, simultaneous left and right ventricular pacing or cardiac resynchronization therapy can improve ventricular synchrony. This can lead to an improvement in hemodynamics, ventricular remodeling, mitral regurgitation, exercise capacity and quality of life. Candidates for cardiac resynchronization therapy include patients with advanced congestive heart failure that is refractory to medical therapy, a QRS duration >130 ms, left ventricular ejection fraction <0.35 and sinus rhythm. Because patients who are candidates for biventricular pacing are at high risk of sudden death, they should be considered for implantation of a biventricular pacing device that also provides defibrillation therapy. This paper reviews biventricular pacing for congestive heart failure, including results of acute hemodynamic studies and randomized clinical trials, patient and device selection, and procedural issues.