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.

Abstract and Introduction

Abstract

Background: Approximately 20,000 permanent pacemakers (PPMs) are implanted annually for bradycardia or atrioventricular (AV) block after cardiac surgery. Little is known about the long-term pacing and mortality outcomes and the temporal trends of these patients.
Methods: We examined 6,268 consecutive patients who underwent cardiac surgery at the Minneapolis Veterans Administration Medical Center between 1987 and 2010. Patients who had a PPM within 30 days of cardiac surgery were identified. Pacemaker interrogation records were retrospectively reviewed and mortality was ascertained.
Results: Overall, 141 (2.2%) patients underwent PPM implantation for high-degree AV block (55%) and bradycardia (45%), 9 ± 6 days after surgery. Age, diuretic use, cardiopulmonary bypass time (CPBT), and valve surgery were independent predictors of PPM requirement. After 5.6 ± 4.2 years of follow-up, 40% of the patients were PPM dependent. Longer CPBT (P = 0.03), PR interval >200 ms (P = 0.03), and QRS interval > 120 ms (P = 0.04) on baseline electrocardiogram predicted PPM dependency. In univariable analysis, PPM patients had a higher long-term mortality than those without PPM (45% vs 36%; P = 0.02). However, after adjusting for age, sex, type of surgery, and CPBT, PPM requirement was not associated with long-term mortality (hazard ratio 1.3; 95% confidence interval 0.9–1.9; P = 0.17). Compared to before, incidence of PPM implantation increased after the year 2000 (1.9% vs 2.6%; P = 0.04).
Conclusion: The majority of patients who require PPM after cardiac surgery are not PPM dependent in the long term. Requiring a PPM after surgery is not associated with long-term mortality after adjustment for patient-related risk factors and cardiac surgical procedure.

Introduction

About 1% of patients who undergo coronary artery bypass graft (CABG) surgery and 6–8% of patients who undergo heart valve surgery require permanent pacemaker (PPM) implantation postoperatively for bradycardia or atrioventricular (AV) block.^[1–6] Considering that about 500,000 CABG and 200,000 valve surgeries are performed annually in the United States,^[7] approximately 20,000 PPM are implanted each year in this context. Advanced age, preexisting cardiac conduction system disease, prolonged cardiopulmonary bypass time (CPBT), and valve surgery are known risk factors for requiring PPM after cardiac surgery.^[6,8–11] A risk score to identify the patients with a higher likelihood of requiring postoperative PPM has also been developed.^[12]

Although the risk factors and indications for postcardiac surgery PPM are well described, critical gaps of knowledge remain. Data on long-term outcomes of PPM recipients after cardiac surgery are limited. Although there is evidence to suggest that AV conduction improves over time in some patients,^[4,6,13,14] incidence and predictors of this phenomenon have not been established. Further, long-term survival of patients who received PPM in comparison to those who did not is unknown. Also, to what extent improvements in cardiac valve technology and surgical techniques that took place in the last decade have impacted the incidence of postcardiac surgery PPM requirement is also unknown. Thus, the objectives of this retrospective cohort study of more than 6,000 postcardiac surgery patients are two-fold: first, to determine long-term clinical outcomes, specifically, pacemaker dependency and survival in recipients of PPM; and second, to examine the secular trends in the incidence of postcardiac surgery PPM implantation.

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Cite this: Long-term Mortality and Pacing Outcomes of Patients with Permanent Pacemaker Implantation after Cardiac Surgery - Medscape - Mar 01, 2011.

Abstract and Introduction
Methods
Results
Discussion
References

Table I. Baseline Characteristics of the 6,268 Patients Who Underwent Crdiac Surgery*
Variables	All Patients (n = 6,268)	Pacemaker Patients (n = 141)	Nonpacemaker Patients (n = 6,127)	P Value
Age	66 ± 10	69 ± 9	66 ± 10	<0.0001
Male	99%	99%	99%	0.9
HTN	80%	85%	80%	0.3
DM	30%	29%	30%	0.3
CVD	21%	24%	21%	0.4
COPD	22%	26%	22%	0.2
Smoker	21%	18%	21%	0.5
Prior heart surgery	10%	14%	10%	0.09
Prior MI	46%	39%	46%	0.1
PVD	29%	31%	29%	0.6
Digoxin use	10%	16%	10%	0.015
Diuretic use	37%	60%	36%	<0.0001
NYHA class III/IV	35%	50%	34%	<0.0001
LV ejection fraction	0.5 ± 0.1	0.5 ± 0.09	0.5 ± 0.1	0.31
Estimated mortality†	4.6 ± 5.7	7.9 ± 7.1	4.3 ± 5.4	<0.0001
Cardiac bypass Time (minutes)	135 ± 51	168 ± 61	134 ± 51	<0.0001
Ischemic time (minutes)	92 ± 41	121 ± 46	92 ± 40	<0.0001

*Continuous data are presented as mean ± standard deviation.
†Estimated mortality risk equals operative mortality estimated by the validated Veterans Affairs Continuous Improvement in Cardiac Surgery Program risk score.
COPD = chronic obstructive pulmonary disease; CVD = cerebrovascular disease; DM = diabetes mellitus; HTN = hypertension; LV = left ventricular; MI = myocardial infarction; NYHA = New York Heart Association; PVD = peripheral vascular disease.

Table II. Incidence of Pacemaker Implantation in Relation to Type of Cardiac Surgery
Type of Surgery	No. of Patients	Patients with PPM n (%)
CABG only	4,678	43 (0.9%)
AVR ± CABG	1,059	64 (6%)
MVR ± CABG	185	14 (7.6%)
Valve repair ± CABG	168	2 (1.2%)
GVR ± CABG	57	0 (0%)
Double valve ± CABG	49	8 (16.3%)
Other surgery*	72	10 (13.9%)
Total	6,268	141 (2.2%)

*Procedures classified as "Other surgery" were atrial or ventricular septal defect closure, myectomy, atrial myxoma removal, pericardiectomy, aneurysmectomy, tricuspid valve replacement, maze procedure, or heartnet procedure. AVR = aortic valve replacement; CABG = coronary artery bypass graft surgery; GVR = great vessel repair; MVR = mitral valve replacement.

Table III. Predictors of Requiring a Permanent Pacemaker Implantation after Cardiac Surgery
Variables	Odds Ratio	95% Confidence Interval	P Value
Univariable predictors
Age (years)	1.05	1.05–1.07	<0.0001
Diuretic use	2.57	1.83–3.61	<0.0001
Digoxin use	1.76	1.11–2.80	0.017
Ischemic time (minutes)	1.01	1.01–1.02	<0.0001
CPB time (minutes)	1.01	1.01–1.01	<0.0001
NYHA class III/IV	1.93	1.37–2.72	<0.0001
Prior heart surgery	1.51	0.94–2.45	0.09
Prior MI	0.72	0.51–1.03	0.07
Estimated mortality	1.06	1.04–1.08	<0.0001
Surgery other than CABG	7.08	4.92–10.18	<0.0001
Multivariable predictors
Age	1.03	1.01–1.05	0.015
Diuretic use	1.71	1.09–2.67	0.019
Surgery type	4.96	2.98–8.26	<0.0001
CPB time	1.00	1.00–1.00	0.05

CPM = cardiopulmonary bypass; NYHA = New York Heart Association; MI = myocardial infarction.

Table IV. Comparison of PPM Dependent versus Nondependent Patients after Cardiac Surgery*
Variable	Nondependent (n = 54)	Pacemaker Dependent (n = 36)	P Value
Age	68 ± 11	71 ± 9	0.19
Male	99%	99%	0.36
HTN	79%	83%	0.67
DM	29%	25%	0.72
CVD	23%	22%	0.96
COPD	16%	17%	0.89
Smoker	18%	8%	0.22
Prior heart surgery	7%	11%	0.48
Prior MI	33%	31%	0.85
PVD	31%	31%	0.96
Digoxin use	7%	14%	0.28
Diuretic use	47%	61%	0.20
NYHA class III/IV	53%	42%	0.30
LV ejection fraction	0.52 ± 0.08	0.53 ± 0.08	0.84
High-degree AV block indication	53%	64%	0.34
CABG only	24%	31%	0.54
Estimated mortality†	6.1 ± 4.8	7.3 ± 5.6	0.32
Cardiac bypass time (minutes)	152 ± 48	186 ± 74	0.03
Ischemic time (minutes)	115 ± 42	132 ± 52	0.16
Follow-up length (days)	2,000 ± 1,864	2,069 ± 1,141	0.03
Ventricular pacing (%)	51 ± 42	91 ± 22	<0.0001
AV block on electrocardiogram	13%	17%	0.73
PR > 200 ms	24%	50%	0.03
QRS > 120 ms	28%	50%	0.04
Long-term mortality	18%	25%	0.4

*Continuous data are presented as mean ± standard deviation.
†Estimated mortality risk equals operative mortality estimated by the validated Veterans Affairs Continuous Improvement in Cardiac Surgery Program risk score.
CABG = coronary artery bypass grafting; CHB = complete heart block; HTN = hypertension; DM = diabetes mellitus; CVD = coronary vascular disease; COPD = chronic obstructive pulmonary disease; LV = left ventricular; MI = myocardial infarction; PVD = peripheral vascular; NYHA = New York Heart Association.

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