Long-term outcomes in young patients with atrioventricular block of unknown aetiology

Abstract

Aims: Atrioventricular block (AVB) of unknown aetiology is rare in the young, and outcome in these patients is unknown. We aimed to assess long-term morbidity and mortality in young patients with AVB of unknown aetiology.

Methods and results: We identified all Danish patients younger than 50 years receiving a first pacemaker due to AVB between January 1996 and December 2015. By reviewing medical records, we included patients with AVB of unknown aetiology. A matched control cohort was established. Follow-up was performed using national registries. The primary outcome was a composite endpoint consisting of death, heart failure hospitalization, ventricular tachyarrhythmia, and cardiac arrest with successful resuscitation. We included 517 patients, and 5170 controls. Median age at first pacemaker implantation was 41.3 years [interquartile range (IQR) 32.7-46.2 years]. After a median follow-up of 9.8 years (IQR 5.7-14.5 years), the primary endpoint had occurred in 14.9% of patients and 3.2% of controls [hazard ratio (HR) 3.8; 95% confidence interval (CI) 2.9-5.1; P < 0.001]. Patients with persistent AVB at time of diagnosis had a higher risk of the primary endpoint (HR 10.6; 95% CI 5.7-20.0; P < 0.001), and risk was highest early in the follow-up period (HR 6.8; 95% CI 4.6-10.0; P < 0.001, during 0-5 years of follow-up).

Conclusion: Atrioventricular block of unknown aetiology presenting before the age of 50 years and treated with pacemaker implantation was associated with a three- to four-fold higher rate of the composite endpoint of death or hospitalization for heart failure, ventricular tachyarrhythmia, or cardiac arrest with successful resuscitation. Patients with persistent AVB were at higher risk. These findings warrant improved follow-up strategies for young patients with AVB of unknown aetiology.

Keywords: Atrioventricular block; Follow-up; Long-term outcomes; Pacemaker implantation; Unknown aetiology; Young.

Atrioventricular block of unknown aetiology presenting before the age of 50 years and treated with pacemaker implantation was associated with a three- to four-fold higher rate of the composite endpoint of death or hospitalization for heart failure, ventricular tachyarrhythmia, or cardiac arrest with successful resuscitation. CI, confidence interval.

Figure 1

Patient inclusion in the period from 1 January 1996 until 31 December 2015. ^aThe control cohort was matched for age and gender.

Figure 2

Cumulative incidence of the primary endpoint^a in patients <50 years when receiving their first pacemaker due to atrioventricular block compared with the general population.^b CI, confidence interval. ^aComposite of death from any cause, heart failure hospitalization, ventricular tachyarrhythmia hospitalization, and cardiac arrest with successful resuscitation. ^bControls from the general population were matched 10:1 for age and gender. Dashed line represents median follow-up time.

Figure 3

Cumulative incidence of the primary endpoint^a in patients^b with persistent or intermittent atrioventricular block compared with the general population.^c AV, atrioventricular; CI, confidence interval. ^aComposite of death from any cause, heart failure hospitalization, ventricular tachyarrhythmia hospitalization, and cardiac arrest with successful resuscitation. ^bPatients <50 years when receiving their first pacemaker due to atrioventricular block. ^cControls from the general population were matched 10:1 for age and gender. Dashed line represents median follow-up time.

Figure 4

Cumulative incidence of secondary endpoints among patients^a and the general population.^b AV, atrioventricular; CI, confidence interval. ^aPatients <50 years when receiving their first pacemaker due to atrioventricular block. ^bControls from the general population were matched 10:1 for age and gender. Deaths were considered competing risk in the non-fatal endpoints. Non-cardiovascular deaths were considered competing risk in the cardiovascular death endpoint.