Long-term Mortality and Pacing Outcomes of Patients with Permanent Pacemaker Implantation after Cardiac Surgery

Syed S. Raza, M.D.; Jian-Ming Li, M.D., Ph.D.; Ranjit John, M.D.; Lin Y. Chen, M.D.; Venkatakrishna N. Tholakanahalli, M.D.; Mackenzie Mbai, M.D.; A. Selcuk Adabag, M.D.

Disclosures

Pacing Clin Electrophysiol. 2011;34(3):331-338. 

In This Article

Results

Baseline Characteristics

The baseline characteristics of the 6,268 cardiac surgery patients are outlined in Table I. The mean age of the study patients was 66 ± 10 years. Overall, 141 (2.2%) patients underwent PPM implantation 9 ± 6 days (median 7 days; interquartile range 5.5–11) after cardiac surgery. Of the implanted pacemakers, 83% were dual chamber and 17% single chamber ventricular devices. The indications for PPM implantation were high-degree AV block in 55% of the cases and bradycardia in 45%, of which the majority (25% of the study cohort) were due to atrial fibrillation with slow ventricular rate. Patients who underwent PPM implantation were older and were exposed to longer ischemic and CPBTs than those who did not need PPM (Table I). PPM patients also had a lower functional capacity and were more likely to use digoxin and diuretics.

On preoperative ECG, 60% of the PPM patients had evidence of conduction block (48% in the His-Purkinje system and 12% in the AV conduction), 14% had atrial fibrillation, and 8% had sinus bradycardia. Preoperative ECG was normal in 18% of the PPM patients.

Surgical Procedures

Overall, 4,678 (75%) patients underwent isolated CABG. The distribution of PPM patients in relation to the type of surgery is outlined in Table II. Whereas <1% of the patients who underwent isolated CABG required PPM, 6–8% of those with aortic or mitral valve replacement and 16% of those with double-valve surgery required PPM (Table II).

Predictors of PPM

Univariate predictors of PPM were age, preoperative digoxin or diuretic use, New York Heart Association class, prior heart surgery, prior myocardial infarction, CPBT, estimated mortality, and undergoing surgery other than isolated CABG (Table III). Of these, age, diuretic use, CPBT, and surgery other than isolated CABG were independent predictors of requiring PPM in multivariable regression analysis (Table III).

Long-term Pacing Outcomes

Of the 141 patients who needed PPM, 90 (64%) had long-term follow-up for 5.6 ± 4.3 years. Of these patients, 36 (40%) were PPM dependent in the long term. Dependent patients were ventricularly paced 91 ± 22% of the time versus 51 ± 42% of nondependent patients (P < 0.0001) at their last visit. Overall, 49% of the patients with high-degree AV block and 38% of the patients with bradycardia at implantation were PPM dependent at follow-up (P = 0.34). Longer CPBT (186 ± 74 vs 152 ± 48 minutes; P = 0.03), PR interval >200 ms (50% vs 24%; P = 0.03), and QRS interval >120 ms (50% vs 28%; P = 0.04) on baseline ECG were associated with late PPM dependency (Table IV). In multivariable analysis, PR interval >200 ms was independently associated with late dependency (odds ratio 4.1; 95% confidence interval [CI] 1.2–17.4; P = 0.025).

Long-term Mortality Outcomes

Over a 7.2 ± 5 years of follow-up, 2,270 (36%) patients died. Patients who had PPM were more likely to die than those without PPM (hazard ratio 1.6; 95% CI 1.3–2.1; P < 0.0001) (Fig. 1). However, after adjusting for age, sex, estimated mortality, type of surgery, and CPBT in multivariable analysis, having a PPM was no longer associated with long-term mortality (hazard ratio 1.3; 95% CI 0.9–1.9; P = 0.17).

Figure 1.

Kaplan-Meier curves for long-term mortality in pacemaker versus nonpacemaker patients after cardiac surgery. Log-rank test P < 0.0001. However, having a pacemaker was not associated with mortality in multivariable analysis (hazard ratio 1.3; 95% confidence interval 0.9–1.9; P = 0.17).

Temporal Trends of PPM Implantation

There was an increase in the incidence of PPM implantation over time. Whereas 1.9% of the patients operated on or before the year 1999 had PPM implantation, this number increased to 2.6% among patients operated in the year 2000 or after (P = 0.04) (Fig. 2). The difference originated from a rise of PPM incidence after non-CABG surgery (from 5.2% to 7%)—particularly aortic valve replacement (from 4.5% to 7.2%)—while PPM incidence after CABG did not change (0.9%). Simultaneously, patients operated after 2000 were older (65 ± 9 vs 66 ± 10 years; P < 0.0001) and were more likely to be taking diuretics (31% vs 44%; P < 0.0001) compared to those operated before this date.

Figure 2.

Trends in pacemaker implantation after cardiac surgery.

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