Implantable cardioverter defibrillators in type 1 diabetes regarding indications, complications and prognosis

Background Patients with diabetes are at increased risk of ventricular arrhythmias, and patients with type 2 diabetes (T2DM) are more frequently in demand of an implantable cardioverter defibrillator (ICD) for primary prevention due to ischemic heart disease as the underlying aetiology. Corresponding information on patients with type 1 diabetes (T1DM) is less well characterized. Purpose To compare indications, underlying aetiologies, prognosis, and complications of de novo ICD implantations among patients with T1DM and T2DM in comparison with individuals free from DM (No-DM). Methods In this retrospective nationwide cohort study, 13,016 Swedish patients undergoing de novo ICD implantation between 2010 and 2021 were included and followed until December 2021. Patients with T1DM (n=128) were compared with No-DM (n=10,045) and T2DM (n=2,843). Data were obtained through linkage of six national registries. Complications were assessed using chi-square tests, and time-to-event analyses for MACE and all-cause mortality were performed using Kaplan–Meier estimates and Cox proportional hazards regression models. Results Patients with T1DM were younger than those with No-DM and T2DM and had longer diabetes duration, lower BMI, and higher HbA1c compared with T2DM (all p<0.0001). Ischemic heart disease was more prevalent in T1DM than in No-DM (55.5% vs. 38.3%, p<0.0001) but was similar in prevalence to T2DM. Heart failure was more frequent in T1DM compared with No-DM (47.7% vs. 38.8%, p=0.0403) but less prevalent compared with T2DM (56.7%, p=0.0428). The proportion receiving ICD for primary prevention was similar between T1DM and T2DM (61.7% vs. 62.7%; p=0.8219) as well as in No-DM. Ventricular arrhythmias and symptom presentation were largely comparable between groups, although palpitations were less frequent in T1DM than No-DM (2.3% vs. 8.0%; p=0.0180). Periprocedural complication rates were overall low. Infection rates were higher in T1DM compared with T2DM (3.1% vs. 1.1%; p=0.0431), but not significantly different compared with No-DM (1.3%; p=0.0790). During follow-up, T1DM was independently associated with higher risk of MACE compared with both No-DM (HR 2.20, 95% CI 1.57–3.06, p<0.0001) and T2DM (HR 1.46, 95% CI 1.04–2.04, p=0.0285) and all-cause mortality was higher compared with No-DM (HR 2.22, 95% CI 1.60–3.07, p<0.0001 but similar between T1DM and T2DM (HR 1.05, 95% CI 0.75–1.47, p=0.777). Conclusions Patients with T1DM undergoing de novo ICD implantation represent a particularly high-risk population with excess cardiovascular morbidity and mortality despite younger age. Although ICD indications, arrhythmic presentation, and procedural complication rates were similar across groups, T1DM was independently associated with significantly increased risk of MACE and mortality compared with No-DM, underscoring the severe cardiovascular risk burden and need for intensified preventive and clinical management in this population.