HEART-FAILURE AND ECHOCARDIOGRAPHIC CHANGES DURING LONG-TERM FOLLOW-UP OF PATIENTS WITH SICK SINUS SYNDROME RANDOMIZED TO SINGLE-CHAMBER ATRIAL OR VENTRICULAR PACING

Background-In patients with sick sinus syndrome, choice of pacing mode has been implicated in the development of congestive heart failure. M ethods and Results-A total of 225 consecutive patients with sick sinus syndrome and intact atrioventricular conduction were randomized to ei ther single-chamber atrial pacing (n=110) or single-chamber ventricula r pacing (n=115). Clinical assessment included New York Heart Associat ion classification, medication, and M-mode echocardiography before pac emaker 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 aerial group (NYHA class I/II/II I/IV: 65/44/4/0 versus 84/22/2/1 patients, P=.010). Increase in NYHA c lass during follow-up was observed in 35 of 113 patients in the ventri cular group versus 10 of 109 in the atrial group (P<.0005). Increase i n dose of diuretics from randomization to last follow-up was significa ntly higher in the ventricular group than in the atrial group (21+/-49 versus 8+/-42 mg furosemide/d, P=.033). The left ventricular fraction al 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 increase d 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=.0 02), but the increase was significantly higher in the ventricular grou p than in the atrial group (P<.0005). Conclusions-During long-term fol low-up, ventricular pacing is associated with a higher incidence of co ngestive heart failure and consumption of diuretics than atrial pacing . This is accompanied by a decrease in left ventricular fractional sho rtening and an increased dilatation of the left atrium in the ventricu lar paced patients.