Heart Failure and Echocardiographic Changes During Long-term Follow-up of Patients With Sick Sinus Syndrome Randomized to Single-Chamber Atrial or Ventricular Pacing

Abstract

Background —In patients with sick sinus syndrome, choice of pacing mode has been implicated in the development of congestive heart failure. Methods and Results —A total of 225 consecutive patients with sick sinus syndrome and intact atrioventricular conduction were randomized to either single-chamber atrial pacing (n=110) or single-chamber ventricular pacing (n=115). Clinical assessment included New York Heart Association classification, medication, and M-mode echocardiography before pacemaker implantation, after 3 months, and subsequently once every year. At long-term follow-up (mean, 5.5±2.4 years), NYHA class was higher in the ventricular group than in the atrial group (NYHA class I/II/III/IV: 65/44/4/0 versus 84/22/2/1 patients, P =.010). Increase in NYHA class during follow-up was observed in 35 of 113 patients in the ventricular group versus 10 of 109 in the atrial group ( P <.0005). Increase in dose of diuretics from randomization to last follow-up was significantly higher in the ventricular group than in the atrial group (21±49 versus 8±42 mg furosemide/d, P =.033). The left ventricular fractional shortening decreased significantly in the ventricular group (from 0.36±0.12 to 0.31±0.08, P <.0005) but not in the atrial group (from 0.35±0.13 to 0.33±0.09, P =.087). The left atrial diameter increased significantly in both treatment groups (ventricular group: from 34±7 to 41±7 mm, P <.0005; atrial group: from 34±6 to 37±7 mm, P =.002), but the increase was significantly higher in the ventricular group than in the atrial group ( P <.0005). Conclusions —During long-term follow-up, ventricular pacing is associated with a higher incidence of congestive heart failure and consumption of diuretics than atrial pacing. This is accompanied by a decrease in left ventricular fractional shortening and an increased dilatation of the left atrium in the ventricular paced patients.