Time course of effects of cardiac resynchronization therapy in chronic heart failure: benefits in patients with preserved exercise capacity.
OBJECTIVE
To assess in patients with chronic heart failure the effect of cardiac resynchronization therapy (CRT) over 12 months' follow-up the time course of the changes in functional and neurohormonal indices and to identify responders to CRT.


METHODS
Eighty-nine patients (74.1 +/- 1 years, left ventricular ejection fraction [LVEF] < 35%), QRS complex duration >150 ms, in stable New York Heart Association (NYHA) class III or IV on optimal medical treatment were prospectively randomized either in a control (n = 45) or CRT (n = 44) group and underwent clinical evaluation, cardiopulmonary exercise testing (CPET), 2D-Echo, heart rate variability (HRV), carotid baroreflex (BRS), and BNP assessments before and at 6- and 12-month follow-up.


RESULTS
In the CRT group, improvement of cardiac indices and BNP concentration were evident at medium term (over 6 months) follow-up, and these changes persisted on a longer term (12 months) (all P < 0.05). Instead CPET indices and NYHA class improved after 12 months associated with restoration of HRV and BRS (all P < 0.05). We identified 26 responders to CRT according to changes in LVEF and diameters. Responders presented less depressed hemodynamic (LVEF 25 +/- 1.0 vs 22 +/- 0.1%), functional (peak VO(2) 10.2 +/- 0.2 vs 6.9 +/- 0.3 ml/kg/min), and neurohormonal indices (HRV 203.6 +/- 15.7 vs 147.6 +/- 10.ms, BRS 4.9 +/- 0.2 vs 3.6 +/- 0.3 ms/mmHg) (all P < 0.05). In the multivariate analysis, peak VO(2) was the strongest predictor of responders.


CONCLUSIONS
Improvement in functional status is associated with restoration of neurohormonal reflex control at medium term. Less depressed functional status (peak VO(2)) was the strongest predictor of responders to CRT.
Piepoli
Massimo F
MF
Heart Failure Unit, Cardiac Department, G. da Saliceto Polichirurgico Hospital, Piacenza, Italy. m.piepoli@ausl.pc.it
Villani
Giovanni Q
GQ
Corrà
Ugo
U
Aschieri
Daniela
D
Rusticali
Guido
G
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002908:Chronic Disease; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D020127:Recovery of Function; D016896:Treatment Outcome