Electrocardiogram Characteristics and Outcomes in an Adult Congenital Heart Disease Population

The electrocardiogram (ECG) is a low-cost, readily available test that may detect dysrhythmia, chamber enlargement, and ischemia in an acquired heart disease population. Use of resting ECG to predict adverse events in an adult congenital heart disease (ACHD) population is unknown. ECG characteristics, outcomes, and vital status of 8130 adults born between 1945 and 2001 with at least two available ECGs during a 10-year surveillance period (2010-2019) were evaluated at baseline and at the end of surveillance. Outcomes included cardiac hospitalizations, cardiac surgery or intervention, or death during surveillance. Broad CHD anatomic groups were analyzed as follows: "left-sided," "right-sided," "single-ventricle," and "neither" to account for differences in loading conditions. Of the cohort, 7.2% died, and 33.0% remained alive without adverse events. ECG parameters associated with mortality include wider QRS duration (QRSd), longer corrected QT (QTc), greater QRS-T angle, left bundle branch block, and rhythm change. Those who died had longer mean baseline QRSd (107.3 ms vs. 101.83 ms, p < 0.0001) and QTc (434.94 ms vs. 425.20 ms, p = 0.0004). Change in QRSd (∆QRSd) was greater in the deceased group than alive (5.18 ms vs. 2.01 ms, p < 0.0001), and in alive with an adverse event compared to those alive without an event (2.78 ms vs. 0.42 ms, p < 0.0001). Mean QRS-T angle remained concordant in those without an adverse event but deviated in the adverse event group (5.65° vs. 22.91°) (p < 0.0001). ECG characteristics and changes over time are associated with adverse cardiac events and mortality in a CHD population. Further study is needed to develop an ECG-based risk model to identify at-risk CHD patients.