FAILURE OF SHORT ATRIOVENTRICULAR DELAY PACING TO IMPROVE HEMODYNAMICFUNCTION IN PATIENTS WITH CONGESTIVE HEART FAILURES

The hemodynamic effects of dual chamber pacing in patients with conges tive heart failure (CHF) remain controversial. In initial anecdotal re ports, right ventricular apical pacing with a 100-msec atrioventricula r (AV) delay was reported to cause marked improvement in hemodynamic a nd ventricular function in patients without a standard pacing indicati on. However, subsequent controlled studies failed to confirm these imp rovements in patients with CHF. To evaluate the effect of ventricular activation on the hemodynamic response to short AV delay pacing, we ev aluated 32 CHF patients undergoing pacemaker implantation. The day fol lowing implantation, a double blind randomized study was performed to evaluate hemodynamic changes during VDD pacing. Three lead configurati ons were used to alter ventricular activation: right ventricular apica l pacing (n=15), right ventricular septal pacing (n=13) and biventricu lar pacing (n=4). All patients had chronic CHF (NYHA class III or IV) with a mean ejection fraction of 0.21+0.05. Compared with intrinsic co nduction, there were no improvements in any hemodymamic parameter with short AV delay pacing. Subgroup analyses of patients with dilated car diomyopathy or with prolonged PR interval also failed to demonstrate a n improvement with pacing in any configuration. We conclude that VDD p acing with a 100-ms AV delay does not improve hemodynamic function in patients with severe CHF. Its use for primary hemodynamic indications remains unproven.