Risk of venous thromboembolism in patients with congenital heart disease: a nationwide, register-based, case-control study.

Aims: Patients with congenital heart disease (CHD) have an increased risk of developing acquired cardiovascular diseases. However, the risk of venous thromboembolism (VTE) in patients with CHD is unknown. We aimed to investigate the incidence and risk of VTE in patients with CHD compared with matched controls without CHD.

Methods and results: Data from Swedish health registers were used to identify all patients with CHD between 1970 and 2017 in Sweden. Each patient with CHD was matched with 10 controls from the Swedish Total Population Register. The primary outcome of the study was an event of VTE. Follow-up was from birth until VTE, death, or the end of the study (2017). Cox proportional hazard models were used to investigate the risk of VTE in patients with CHD and controls. A total of 67 814 patients with CHD and 583 709 matched controls were identified and included in the study. During a mean follow-up of 15.9 (SD ± 12.5) years, 554 (0.8%) patients with CHD and 1571 (0.3%) controls developed VTE. The risk of VTE was 3.3 [95% confidence interval [CI] 2.6-3.4) times higher in patients with CHD than in controls. Patients with conotruncal defects had the highest risk of VTE (hazard ratio 7.06, 95% CI 5.52-9.03).

Conclusion: In our nationwide study, we found that the risk of VTE in patients with CHD was more than three times higher than in matched controls. The highest risk of VTE was in patients with the most complex lesions. Further research is crucial to clarify the underlying risk factors and prevent VTE in patients with CHD.