The Heritability of Supraventricular Tachycardia: A Nationwide Study in Danish Twins

BACKGROUND: Supraventricular tachycardia (SVT) is a common type of arrythmia leading to patient distress and substantial health care utilization. Although the mechanistic underpinnings of SVT are well elucidated, the etiologies remain unknown.

OBJECTIVES: This study aimed to determine to what extent SVT may be heritable using a classical biometrical twin study design.

METHODS: Monozygotic and same-sex dizygotic twin pairs born in Denmark, in which one or both members were diagnosed with SVT between 1977 and 2024, were identified through the Danish Twin Registry and the Danish National Patient Registry. The risk in the co-twin following the index-twin's diagnosis was estimated by using Cox proportional hazards models. Heritability of SVT was assessed by using probandwise concordance rates and biometrical models.

RESULTS: Of 32,324 twin pairs (12,006 monozygotic and 20,318 dizygotic pairs), at least one SVT diagnosis was identified in 663 twin pairs. After an SVT diagnosis in the index-twin, the risk of SVT was significantly higher in monozygotic co-twins compared with dizygotic co-twins (HR: 3.61; 95% CI: 1.35-9.63; P = 0.01), which remained significant after adjusting for age and sex (HR: 3.3; 95% CI: 1.24-8.89; P = 0.01). The probandwise concordance rate was significantly higher in monozygotic twins compared with dizygotic twins (9% vs 3%; P < 0.001). Biometrical models indicated that 35% of SVT risk could be attributed to genetics and 65% to unique environmental components.

CONCLUSIONS: Based on a large nationwide population of monozygotic and same-sex dizygotic twins, this is the first study to quantify the genetic and environmental contributions to SVT.