[Acute hemodynamic effects]

Several studies on the acute effect of cardiac resynchronization in patients with advanced heart failure (HF) and left bundle branch block (LBBB) have shown that left and biventricular stimulation increase pulse pressure and contractility, while patients with a QRS complex <150 ms may deteriorate during stimulation. Patients with LBBB, severe HF and a QRS width >150 ms underwent right, left and biventricular stimulation at different AV delays. Acute response was defined as > or =10% pulse pressure increase. 165 of 188 patients (88%) in sinus rhythm (47 women, mean age 62.5+/-10 years, ejection fraction 23+/-8%, NYHA class 3.1+/-0.3) were regarded acute responders. 10% of 103 patients with dilated cardiomyopathy and 16.5% of 79 patients with coronary artery disease were considered non-responders. 29 patients (81%) with 2 posterolateral veins were acute responders with 10 of them (33%) being responders in only one vein. 54 patients had a higher pulse pressure increase (10.7+/-10.6%) with atrio-left ventricular stimulation, 48 patients with atrio-biventricular stimulation (9.8+/-6.4%). At one-year follow-up, heart failure had significantly (p<0.0001) improved from NYHA class 3.1+/-0.4 to 2.1+/-0.7, VO(2)peak from 12.7+/-2.8 to 15.9+/-3.6 ml/min/kg. Left ventricular enddiastolic diameter being an indicator of reverse remodeling decreased from 80.5+/-10.5 to 73.3+/-13 (p<0.0001). Hemodynamic testing before CRT allows for the identification of acute non-responders as well as the best mode and site of stimulation and the optimal atrioventricular delay in responders.