Longitudinal association of electrocardiogram abnormalities with major adverse cardiac events in people with Type 2 diabetes: the Hoorn Diabetes Care System cohort

Aims To investigate the association of (changes in) electrocardiogram (ECG) abnormalities with incident major adverse cardiac events (MACE) in people with Type 2 diabetes (T2D) without pre-existing cardiovascular disease (CVD). Methods and results A prospective longitudinal study of 11 993 people with T2D without known CVD from the Hoorn Diabetes Care System cohort. Annually repeated measurements (1998-2018), included cardiovascular risk factors, over 70 000 ECG, and self-reported cardiovascular events. ECG abnormalities were classified according to the Minnesota Classification as prolonged PR duration, prolonged QRS duration, left QRS-axis, QS pattern, ST-segment/T-wave abnormalities, or tall R-wave. The association of ECG abnormalities with MACEs was assessed using time-dependent Cox-regression models, adjusted for time-varying cardiovascular risk factors, and medication use [hazard ratios (HRs) with 95% confidence intervals (CIs)]. During a median follow-up of 6.6 (IQR, 3.1-10.7) years, 5445 (45.4%) of the participants had an ECG abnormality (prevalent or incident) at any of the median 6 (IQR, 3-10) annual ECG recordings, and 905 people (7.5%) had a MACE (529 coronary heart disease (CHD), 250 heart failure (HF), and 126 sudden cardiac arrest (SCA)). After adjustment, most ECG abnormalities were associated with HF: prolonged QRS duration [HR, 4.01 (95% CI, 2.67-6.03)], QS pattern [2.68 (0.85-8.49)], ST-segment/T-wave abnormalities [4.26 (2.67-6.80)], and tall R-wave [2.23 (1.33-3.76)]. Only QS pattern [2.69 (1.20-6.03)] and ST-segment/T-wave abnormalities [2.11 (1.48-3.02)] were associated with CHD. These associations were robust across age, sex, hypertension, or estimated CVD risk subgroups. Conclusion In people with T2D without pre-existing CVD, ECG abnormalities related to decelerated conduction, ischaemia, and hypertrophy are predominantly early signs of emerging HF, while only abnormalities related to ischaemic disorders are signs of CHD. Lay Summary In this cohort study of 11 993 people with Type 2 diabetes (T2D) that were still free of cardiovascular disease (CVD), the people with electrocardiogram (ECG) abnormalities were up to four times as likely to experience heart failure and up to twice as likely to experience a heart attack, regardless of their age, sex, blood pressure, or estimated risk of CVD. center dot Most ECG abnormalities are related to a higher risk of heart failure, but only ECG abnormalities that indicate reduced oxygen supply to the heart are related to a higher risk of a heart attack. center dot Periodical ECG examinations can help detect developing heart disease in an early stage for all people with T2D still free of CVD.