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.