Incidence of and risk factors for sick sinus syndrome in the general population

Abstract

Background: Little is known about the incidence of and risk factors for sick sinus syndrome (SSS), a common indication for pacemaker implantation.

Objectives: This study sought to describe the epidemiology of SSS.

Methods: This analysis included 20,572 participants (mean baseline age 59 years, 43% male) in the ARIC (Atherosclerosis Risk In Communities) study and the CHS (Cardiovascular Health Study), who at baseline were free of prevalent atrial fibrillation and pacemaker therapy, had a heart rate of ≥ 50 beats/min unless using beta blockers, and were identified as of white or black race. Incident SSS cases were identified by hospital discharge International Classification of Disease-revision 9-Clinical Modification code 427.81 and validated by medical record review.

Results: During an average 17 years of follow-up, 291 incident SSS cases were identified (unadjusted rate 0.8 per 1,000 person-years). Incidence increased with age (hazard ratio [HR]: 1.73; 95% confidence interval [CI]: 1.47 to 2.05 per 5-year increment), and blacks had a 41% lower risk of SSS than whites (HR: 0.59; 95% CI: 0.37 to 0.98). Incident SSS was associated with greater baseline body mass index, height, N-terminal pro-B-type natriuretic peptide, and cystatin C, with longer QRS interval, with lower heart rate, and with prevalent hypertension, right bundle branch block, and cardiovascular disease. We project that the annual number of new SSS cases in the United States will increase from 78,000 in 2012 to 172,000 in 2060.

Conclusions: Blacks have a lower risk of SSS than whites, and several cardiovascular risk factors were associated with incident SSS. With the aging of the population, the number of Americans with SSS will increase dramatically over the next 50 years.

Keywords: epidemiology; pacemaker; sick sinus syndrome; tachy-brady syndrome.

Figure 1. Estimated number of incident sick sinus syndrome (SSS) cases per year, overall and by age group, United States, 2012–2060

The shaded area corresponds to the range of estimates based on the 95% confidence intervals of age-specific rates.

Figure 2. Meta-analyzed Multivariate Adjusted Hazard Ratios of Incident Sick Sinus Syndrome According to Participant Characteristics

^*Results from one multivariate model that includes all of the listed variables and study clinic as covariates. ^†Cardiovascular (CV) event denotes history of myocardial infarction (MI), heart failure (HF), or stroke at baseline. ^§Each row represents a separate multivariable model; each model was adjusted for baseline age, sex, race, study clinic, hypertension, diabetes, BMI, current smoking, LDL-cholesterol, and history of a CV event at baseline (MI, HF, or stroke).

Central Illustration. Epidemiology of Sick Sinus Syndrome

Demographic variables, such as increasing age, white race, and cardiovascular risk factors (obesity, hypertension, diabetes) may affect the sinoatrial node promoting the pathological and electrical substrate of sick sinus syndrome. Variables in the ECG and blood biomarkers could be used to characterize the substrate. Eventually, alterations in the sinoatrial node will lead to signs and symptoms of sinus node dysfunction resulting in a clinical diagnosis of sick sinus syndrome.