Cardiac Arrhythmias and Conduction Abnormalities in Patients with Type 2 Diabetes
Authors: Rawshani Araz , McGuire Darren K. , Omerovic Elmir , Sattar Naveed , McMurray John J.V. , Smith Ulf , Redfors Björn , Bergfeldt Lennart , Eliasson Björn , Borén Jan , Bhatt Deepak L , Bergström Göran , Rawshani Aidin 
Published: August 2022

Aims/hypothesisThe association between type 2 diabetes (T2D) and the development of cardiac arrhythmias and conduction disturbances has not been extensively studied. Methods Arrhythmia was defined as atrial fibrillation and flutter (AF/AFl), ventricular tachycardia (VT) and ventricular fibrillation (VF), and conduction abnormality as sinus node disease (SND), atrioventricular (AV) block or pacemaker implantation, and intraventricular conduction blocks (IVCB). Incidence rates and Cox regression were used to compare outcomes, and to assess optimal levels for cardiometabolic risk factors and risk associated with multifactorial risk factor control (i.e., HbA1c, LDL-C, systolic blood pressure (SBP), BMI and eGFR), between patients with versus without T2D.ResultsThe analyses included data from 617,00 patients with T2D and 2,303,391 matched controls. During the study period, 219,444 developed AF/AFI, 33,511 cases of SND, AV-block or pacemaker implantation, 11,029 cases of IVCB and 10,110 cases of VT/VF. Patients with diabetes and the general population demonstrated a gradual increase in rates for AF/AFl and conduction abnormalities. For patients with versus without T2D, risks for cardiac arrhythmias were higher, including for AF/AFl (HR 1.17, 95% CI, 1.16 to 1.18), the composite of SND, AV-block or pacemaker implantation (HR 1.40, 95% CI, 1.37 to 1.43), IVCB (HR 1.23, 95% CI, 1.18 to 1.28) and VT/VF (HR 1.08, 95% CI, 1.04 to 1.13). For patients with T2D who had selected cardiometabolic risk factors within target ranges, compared with controls, risk of arrythmia and conduction abnormalities for T2D vs not were: AF/AFl (HR 1.09, 95% CI, 1.05 to 1.14), the composite of SND, AV-block or pacemaker implantation (HR 1.06, 95% CI, 0.94 to 1.18), IVCB (HR 0.80, 95% CI, 0.60 to 0.98), and for VT/VF (HR 0.97, 95% CI, 0.80 to 1.17). Cox models showed a linear risk increase for SBP and BMI, while eGFR showed a U-shaped association.Conclusion/interpretationIndividuals with T2D had a higher risk of arrhythmias and conduction abnormalities than controls, but excess risk associated with T2D was not evident among patients with T2D with all risk factors within target range. BMI, SBP and eGFR displayed significant associations with outcomes among patients with T2D.Research in contextTo investigate long-term trends in incidence rates for cardiac arrhythmias and conduction abnormalities among patients with T2D and the general population, and to investigate if cardiometabolic risk factor levels lower than recommended therapeutic target values was associated with lower risk for outcomes and risk associated with multifactorial risk factor control.Our results show that incidence of arrhythmias and conduction abnormalities is gradually increasing among both patients with T2D and matched controls. BMI, SBP and eGFR shows a clear risk association for cardiac outcomes in patients with diabetes. Finally, according to observational analyses, excess risk for arrhythmias among individuals with T2D and several risk factors within target range is associated with just slightly higher risk among patients with T2D, compared with matched controls.