Familial Associations of Complete Atrioventricular Block: A National Family Study in Sweden.

BACKGROUND: Complete atrioventricular block (CAVB) is a major reason for implantation of permanent pacemakers, but knowledge of CAVB inheritance is sparse. This nationwide study aimed to determine the occurrence of CAVB in first-, second-, and third-degree relatives (full siblings, half-siblings, and cousins). METHODS: The Swedish multigeneration register was linked to the Swedish nationwide patient register for the period 1997 to 2012. All Swedish full sibling, half-sibling, and cousin pairs born to Swedish parents between 1932 and 2012 were included. Competing risks and time-to-event, subdistributional hazard ratios (SHRs) according to Fine and Gray and hazard ratios using Cox proportional hazards model were estimated using robust SEs and considering the relatedness of relatives (full siblings, half-siblings, cousins). Additionally, odds ratios (ORs) for CAVB were calculated for traditional cardiovascular comorbidities. RESULTS: The study population (N=6 113 761) consisted of 5 382 928 full siblings, 1 266 391 half-siblings, and 3 750 913 cousins. In total, 6442 (0.11%) unique individuals were diagnosed with CAVB. Of these, 4200 (65.2%) were males. SHRs for CAVB were 2.91 for full siblings (95% CI, 2.43-3.49), 1.51 for half-siblings (0.56-4.10), and 3.54 for cousins (1.73-7.26) of affected individuals. Age-stratified analysis showed higher risk in young individuals born from 1947 to 1986: SHR, 5.30 (3.78-7.43) for full siblings, SHR, 3.30 (1.06-10.31) for half-siblings, and SHR, 3.15 (1.39-7.17) for cousins. Similar familial HRs according to Cox proportional hazard model and ORs were obtained without any major differences. Apart from familial relationship, CAVB was associated with hypertension (OR, 1.83), diabetes (OR, 1.41), coronary heart disease (OR, 2.08), heart failure (OR, 5.01), and structural heart disease (OR, 4.59). CONCLUSIONS: Risk of CAVB among relatives of affected individuals depends on relationship degree, being strongest in young siblings. The familial association extending to third-degree relatives indicates presence of genetic components in the cause of CAVB.

Hospitalization rate of paroxysmal supraventricular tachycardia in Sweden.

INTRODUCTION: The hospitalization rate of paroxysmal supraventricular tachycardia (PSVT) in a nationwide study is not established. We determined age- and sex-specific hospitalization rates and time trends for hospitalized PSVT in the Swedish population between 1987 and 2010. METHODS: This nationwide study is based on the Swedish Hospital Discharge Register. The patients with first PSVT diagnoses between January 1987 and December 2010 were identified. RESULTS: A total of 42,765 individuals with PSVT were diagnosed (mean age 60 years; 44% males). The overall age- and sex-adjusted hospitalization rate was 20 per 100,000 person-years. The hospitalization rate increased with advancing age with highest hospitalization rates in individuals aged 80-84 years (67.12 per 100,000 person-years) and did not change significantly over time. A total of 20,011 (46.8%) patients had "lone" PSVT without any comorbidities. Lone PSVT patients were younger than PSVT patients with comorbidities (mean age 54 vs. 67 years, p = .0002). CONCLUSIONS: This study showed a slight preponderance for females and stable hospitalization rate of PSVT over time; the hospitalization rate increased with age. A high proportion of PSVT patients had no comorbidities. They were affected at a younger age than patients with comorbidities, which suggests an inherent predisposition. Key messages This study represents the first extensive and nationwide hospitalization study of PSVT. Hospitalization is highest in old age but a bimodal pattern was observed with a small peak in the first years of life. Patients with lone PSVT are younger than those with comorbidities; which suggests an inherent predisposition.