Indications for de novo pacemaker implantation, prognosis and complications in patients with and without type 2 diabetes mellitus

Background Patients with diabetes mellitus (DM) face higher risk of cardiovascular disease including arrythmias. Bradyarrhythmias are more frequent in patients with than those without DM and it seems like patients with DM have a higher need of pacemaker treatment compared to controls. The underlying mechanism behind this association is not fully explored. Purpose To assess differences in indications, complications, and outcomes between patients with and without type 2 DM (T2DM) with a newly implanted pacemaker. Methods This cohort study comprises adult patients who underwent de novo pacemaker implantation 2010–2021, using data from the Swedish ICD and Pacemaker Registry. Pacemaker indications (i.e.., etiology, ECG findings, symptoms) and complications during the first year after the implantation were analyzed using chi-square tests. T2DM was obtained from the Swedish National Diabetes Registry while comorbidities and outcomes like major adverse cardiovascular events (MACE) and all-cause mortality were evaluated by means of several national registries and Kaplan-Meier/Cox regressions models. Results Among 95,548 patients, 19% had T2DM before pacemaker implantation. T2DM patients had a mean DM duration of 12.8 years before the implantation. They were older (mean age 78.1 vs 76.7 years), overweight (mean BMI 29.4 kg/m²) and had a more frequent history of cardiovascular comorbidities compared to pacemaker patients without DM. Cardiac fibrosis (T2DM 80.3% vs. no DM 82.5%, p<0.0001) and ischemic heart disease (IHD) (9.5% vs. 6.0%, p<0.0001) were the most commonly reported reasons behind the need of pacemaker treatment. AV-block III and sick sinus syndrome were the most frequent ECG findings in both groups. Procedural complications were slightly lower in T2DM patients (4.0% vs. 4.3%, p<0.001), with electrode dislocation as the most common problem in both groups. The adjusted (patient demographics, IHD and heart failure) post implant risk of all-cause mortality (HR: 1.39, 95% CI [1.36-1.43]) and MACE (HR: 1.33, 95% CI [1.29-1.38]) was higher in patients with than without T2DM. Conclusions In patients undergoing pacemaker implantation, cardiac fibrosis is the most common underlying etiology irrespective of DM. T2DM was associated with a more dismal long-term outcome despite similar post-implant complication rates. Their elevated risks of all-cause mortality and MACE highlight the need for a comprehensive risk factor management to improve the prognosis.