Cardiac resynchronization therapy and other new approaches for the treatment of heart failure in the elderly.

Approximately 15% to 20% of patients with systolic heart failure have a QRS duration greater than 120 ms, which is most commonly seen as left bundle-branch block (LBBB). In LBBB, the left ventricle is activated through the septum from the right ventricle, resulting in a significant delay between the onset of right (RV) and left ventricular (LV) contraction. In patients with LV dysfunction, ventricular dyssynchrony caused by LBBB places the already failing left ventricle at an additional mechanical disadvantage. Ventricular dyssynchrony appears to have a deleterious impact on the natural history of heart failure, as a wide QRS complex has been associated with increased mortality in patients experiencing heart failure. On the basis of these observations, investigators hypothesized that patients with LV dysfunction and delayed ventricular conduction would benefit from pacing at sites that achieve a more favorable contraction pattern, and correct interatrial and/or interventricular conduction delays to maintain optimal atrial-ventricular (AV) synchrony. Multiple clinical trials of cardiac resynchronization therapy have demonstrated that it is safe and effective, with patients achieving significant improvement in both clinical symptoms as well as multiple measures of functional status and exercise capacity. Moreover, it has reduced measures of morbidity and mortality in several studies. Thus, cardiac resynchronization therapy should be routinely offered to eligible patients experiencing heart failure.