Comparison between apical and infundibular pacing in patients with primaryor ischaemic dilated cardiomyopathy

Dual chamber pacing has been proposed as an alternative treatment to patien ts with cardiac failure refractory to optimal medical therapy. The influence of the site of ventricular pacing was studied in 15 patients with an average age of 68.7 +/- 8.7 years with dilated cardiomyopathies and an average left ventricular ejection fraction of 22.3 +/- 6.8%. Three temp orary USCI electrodes were positioned in the right atrium, the right ventri cular outflow tract (RVOT) and the right ventricular apex, The average dura tion of the QRS complexes and the, haemodynamic parameters (PAP, PCP and ca rdiac index) were measured in sinus rhythm and during DDD apical, RVOT and simultaneous apical and RVOT pacing. The RVOT and simultaneous pacing significantly reduced the QRS duration (13 5 +/- 14 ms and 137 +/- 17 ms, p < 0.0001 respectively) compared with apica l pacing (150 +/- 19 ms). The mean PAP and mean PCP remained unchanged in t he different modes of pacing but the cardiac index increased significantly during RVOT pacing (2.99 +/- 0.67 l/min/m(2)) and simultaneous pacing (3 +/ - 0.77 l/min/m(2)) compared with apical pacing (2.66 +/- 0.62 l/min/m(2)) ( p < 0.001 and p < 0.01 respectively) and compared with sinus rhythm (2.62 /- 0.7 l/min/m(2)) (p < 0.001 and p < 0.005 respectively). This study suggests that better results may be obtained with RVOT screw in lead than with the traditional right ventricular apical electrode.