Risk Factors Associated With Atrioventricular Block

Abstract

Importance: Pacemaker implantations as a treatment for atrioventricular (AV) block are increasing worldwide. Prevention strategies for AV block are lacking because modifiable risk factors have not yet been identified.

Objective: To identify risk factors for AV block in community-dwelling individuals.

Design, setting, and participants: In this population-based cohort study, data from the Mini-Finland Health Survey, conducted from January 1, 1978, to December 31, 1980, were used to examine demographics, comorbidities, habits, and laboratory and electrocardiographic (ECG) measurements as potential risk factors for incident AV block. Data were ascertained during follow-up from January 1, 1987, through December 31, 2011, using a nationwide registry. A total of 6146 community-dwelling individuals were included in the analysis performed from January 15 through April 3, 2018.

Main outcomes and measures: Incidence of AV block (hospitalization for second- or third-degree AV block).

Results: Among the 6146 participants (3449 [56.1%] women; mean [SD] age, 49.2 [12.9] years), 529 (8.6%) had ECG evidence of conduction disease and 58 (0.9%) experienced a hospitalization with AV block. Older age (hazard ratio [HR] per 5-year increment, 1.34; 95% CI, 1.16-1.54; P < .001), male sex (HR, 2.04; 95% CI, 1.19-3.45; P = .01), a history of myocardial infarction (HR, 3.54; 95% CI, 1.33-9.42; P = .01), and a history of congestive heart failure (HR, 3.33; 95% CI, 1.10-10.09; P = .03) were each independently associated with AV block. Two modifiable risk factors were also independently associated with AV block. Every 10-mm Hg increase in systolic blood pressure was associated with a 22% higher risk (HR, 1.22; 95% CI, 1.10-1.34; P = .005), and every 20-mg/dL increase in fasting glucose level was associated with a 22% higher risk (HR, 1.22; 95% CI, 1.08-1.35; P = .001). Both risk factors remained statistically significant (HR for systolic blood pressure, 1.26 [95% CI, 1.06-1.49; P = .007]; HR for glucose level, 1.22 [95% CI, 1.04-1.43; P = .01]) after adjustment for major adverse coronary events during the follow-up period. In population-attributable risk assessment, an estimated 47% (95% CI, 8%-67%) of AV blocks may have been avoided if all participants exhibited ideal blood pressure and 11% (95% CI, 2%-21%) may have been avoided if all had a normal fasting glucose level.

Conclusions and relevance: In this analysis of data from a population-based cohort study, suboptimal blood pressure and fasting glucose level were associated with AV block. These results suggest that a large proportion of AV blocks are assocated with these risk factors, even after adjusting for other major adverse coronary events.

Figure 1.. Multivariable Adjusted Hazard Ratios (HRs) for Incident Atrioventricular (AV) Block

Incident AV block was defined as a hospitalization for second- or third-degree AV block during the follow-up. All covariates listed were included in multivariable models. Unless otherwise indicated, hazard ratios (HRs) were interpreted as a hazard for the presence (vs absence) of each categorical variable or for the increase of 1 unit of each continuous variable. To convert cholesterol to millimoles per liter, multiply by 0.0259; glucose level to millimoles per liter, multiply by 0.0555. ^aInterpreted as a hazard for every 5-year increase. ^bInterpreted as a hazard for every 10-mm Hg increase. ^cInterpreted as a hazard for every 20-mg/dL increase. ^dInterpreted as a hazard for every 10-millisecond increase.

Figure 2.. Cumulative Incidence of Atrioventricular Block Taking Death as a Competing Risk Into Account

Data are shown according to quartiles of fasting glucose level and systolic blood pressure. The quartiles for systolic blood pressure were less than 126, 126 to 136, 137 to 152, and greater than 152 mm Hg. The quartiles for glucose level were less than 87.3, 87.3 to 93.1, 93.2 to 100.4, and greater than 100.4 mg/dL (to convert to millimoles per liter, multiply by 0.0555).

Figure 3.. Multivariable-Adjusted Population-Attributable Risks of Systolic Blood Pressure and Fasting Glucose Level for Atrioventricular (AV) Block

The dark blue bars represent the population-attributable risk for the listed covariates. The light blue bars represent the population-attributable risk after censoring participants from the model at the occurrence of major adverse coronary events (MACEs) (unstable angina pectoris, myocardial infarction, angioplasty, and/or coronary artery bypass graft). All models were adjusted for age, sex, history of myocardial infarction, history of congestive heart failure, and total cholesterol level. In addition, models for systolic blood pressure were adjusted for fasting glucose level, and models for fasting glucose level were adjusted for systolic blood pressure. Error bars represent 95% CIs.