Introduction: Biventricular pacing improves functional status in the majority of patients with drug-refractory heart failure, dilated cardiomyopathy, and interventricular conduction delay. The aim of this study was to analyze the baseline clinical and functional data of a cohort of patients implanted with a biventricular stimulation system in a single-center experience, to verify if the pathophysiologic characteristics of patients affect outcome, and to determine if preliminary identification of the right candidates for the new therapy is possible with noninvasive parameters.
Methods and results: Since March 1999, 52 patients with advanced heart failure (idiopathic cardiomyopathy 50%, ischemic cardiomyopathy 35%, other etiology 15%) and left bundle branch block underwent cardiac resynchronization and were followed prospectively. Paired analysis over mean (+/- SD) follow-up of 348 +/- 154 days showed an overall significant decrease of QRS width (baseline 194 +/- 33.2 msec vs follow-up 159.6 +/- 20.1 msec), New York Heart Association (NYHA) functional class (baseline 3.2 +/- 0.5 vs follow-up 2.3 +/- 0.5), quality-of-life score (baseline 54 +/- 25 vs follow-up 25 +/- 16), and increase of maximal VO2 (baseline 12.6 +/- 2.5 mL/kg/min vs follow-up 15.0 +/- 3.3 mL/kg/min). There were 80% responders (documented, persistent decrease > or = 1 NYHA class) and 20% nonresponders (same NYHA class or decline of status; need for heart transplant; death due to progressive pump failure). No significant differences in baseline clinical and functional variables between the two subgroups were observed. In responders, there was a highly significant global improvement of all variables; in nonresponders, no parameters changed between baseline and follow-up.
Conclusion: These data confirm the role of biventricular pacing in improving the functional status of the great majority of a selected patient population having advanced heart failure and left bundle branch block with wide QRS complex. Basal demographic, clinical, and functional characteristics are not helpful in preliminary selection of responders. Simple evaluation of NYHA class confirms favorable outcome (improvement of functional and hemodynamic status).