The bioprosthesis type and size influence the postoperative incidence of permanent pacemaker implantation in patients undergoing aortic valve surgery

Background. Long-standing aortic stenosis (AS) causes significant progressive left ventricular dysfunction and may result in subendocardial ischaemia and conduction disorders. Though stentless bioprosthesis show better haemodynamic profiles compared with stented, yet debate exists about the differential effects of valve substitutes on the incidence of permanent pacemaker (PPM) implantation following aortic valve replacement (AVR). Methods. 510 consecutive patients aged 65-77 years with predominant AS accepted for isolated non-emergent AVR (360 received stented and 150 stentless) were studied over three years period. A stepwise logistic regression analysis was used and statistical significance was accepted at P < 0.05. Results. Mean age +/- standard deviation for the stented group was 70.43 +/- 7.2 and the stentless was 61.7 +/- 12.3. Perioperative (30-day) mortality was 1% (5 of the 510 patients). Smaller aortic prosthesis size was identified as a significant predictors of hospital mortality [univariate and multivariate analysis (P < 0.05)]. Risk factors identified for PPM by univariate analysis were: preoperative: age, left atrial enlargement (LAE), MI, left bundle branch block (LBBB), poor ejection fraction < 35% (P < 0.05), postoperative; bypass time > 100 min with x-clamp time > 70 min, concomitant aortic surgery and prosthetic valve size <= 21 mm (P < 0.05). Multivariate analysis identified the preoperative MI (P = 0.003), poor ejection fraction < 35% (P = 0.007), LAE, (P = 0.001) and LBBB (P = 0.002), the perioperative variables; bypass time > 100 min with x-clamp time > 70 min (P < 0.001) and prosthetic valve size <= 21 mm (P = 0.003). Test of interaction analysis identified valve type as an important predictor of PPM (P = 0.01) Conclusions. The results demonstrated that where stentless valves required longer bypass and cross clamp times, more stented valves were small (< 21 mm, P < 0.05). In precis, this suggests that prevalence of PPM seems to be dependent on the size and type of bioprosthesis used in patients undergoing isolated AVR and this incidence of PPM is twice in stentless group (18% vs. 9.1%, P = 0.01).