Venous thromboembolism in patients with implantable cardioverter-defibrillators

To examine the incidence of venous thromboembolism (VTE) and its risk factors among patients with implantable cardioverter-defibrillators (ICDs).

All first-time ICD recipients in Denmark during 2000–12 were identified from medical databases. Incident VTEs were ascertained, overall and according to gender, age, Charlson Comorbidity Index score (no, moderate, or severe comorbidity), prior pacemaker or cardiac resynchronization therapy (CRT-D) implantation, and ICD type (single-chamber, dual-chamber, or CRT-D). We computed the risk of VTE within 3 months and 5 years of implantation, taking death into account as a competing risk. We used Cox proportional hazards regression to compute hazard ratios as estimates of incidence rate ratios (IRRs). Among 8132 ICD recipients, 136 VTEs were diagnosed during up to 13 years of follow-up (median = 3.0 years). The VTE incidence rate was thus 4.5 per 1000 person-years [95% confidence interval (CI): 3.7–5.2]. Venous thromboembolism risk was 0.3% (95% CIs ranging from 0.1 to 0.7%) within 3 months following ICD implantation regardless of comorbidity level. Within 5 years following implantation it was 1.4% (95% CI: 0.8–2.3%), 1.3% (1.0–1.8%), and 3.2% (95% CI: 2.4–4.1%) for patients with no, moderate, and severe comorbidity, respectively. Overall, severe comorbidity conferred a 2.7-fold higher incidence rate ratio than no comorbidity (95% CI: 1.6–4.6). Incidence rate ratios did not differ by gender, age, or ICD type.

Three-month risk of VTE following ICD implantation was 0.3% regardless of comorbidity level. Five-year risk of VTE following ICD implantation was 1.9% and more than twice as high for patients with severe comorbidity as for patients without comorbidity.