Electrocardiographic Evolution in Kidney Transplant Recipients: A Single-Center Outcome Study

Background and aim. Chronic kidney disease (CKD) has emerged as a global health priority and a major cause of mortality worldwide. Most adverse events and deaths in patients with CKD and those undergoing dialysis patients are related to cardiovascular disease (CVD). Kidney transplantation remains the favored approach, as it is associated to an increase in the quality of life and reduced overall and cardiovascular mortality compared to dialysis. However, cardiovascular risk remains high in kidney transplanted patients, and cardiovascular risk stratification is fundamental both before and after surgery. ECG remains an accessible and easy tool that is recommended for perioperative for monitoring. This study aimed to investigate the role of postoperative ECG in kidney transplant recipients, by analyzing the emergence of new electrocardiographic alterations and their correlation with major adverse cardiovascular events (MACE) in the years following transplantation. Methods. This retrospective single-center observational cohort study included consecutive adult kidney transplant recipients who underwent transplantation at Padua University Hospital in 2021 and had both preoperative and postoperative 12-lead ECGs available. Baseline clinical, laboratory, electrocardiographic, perioperative, and outcome data were collected from the institutional records. The primary endpoint was a composite of major adverse cardiovascular events (MACE, defined as a composite of myocardial infarction, stroke, and cardiovascular mortality) heart failure, graft-related outcomes (including acute rejection and graft loss), and all-cause mortality. Cox regression analyses were performed to assess the association between incident T-wave inversion and MACE. Results. Among the 129 kidney transplant recipients, the median age was 48 years (IQR, 40–57), and 38 patients (29%) were women. Baseline ECG abnormalities were common, with pre-transplant T-wave inversion observed in 62 (48%) patients. After transplantation, incident T-wave inversion was the most frequent newly detected ECG abnormality, occurring in 25 (19%) patients. Patients with incident T-wave inversion had a higher prevalence of pre-transplant ST-segment depression than those without incident T-wave inversion (20% vs. 4%; p=0.014) and lower postoperative potassium levels (4.0 mmol/L [IQR, 3.7–4.4] vs. 4.4 mmol/L [IQR, 4.0–5.2]; p=0.024). The high-sensitivity cardiac troponin I levels were numerically higher in patients with incident T-wave inversion, although this difference was not statistically significant. Over a median follow-up of 47 months (IQR, 37–52), MACE occurred in 11 patients (9%). Incident T-wave inversion was associated with a numerically higher risk of MACE in the univariable analysis, without reaching statistical significance (HR, 2.34; 95% CI, 0.68–7.98; p=0.17). In the multivariable analysis, age at transplantation was independently associated with MACE (HR per year, 1.10; 95% CI, 1.03–1.17; p=0.003), whereas incident T-wave inversion retained a similar but non-significant point estimate (HR, 2.21; 95% CI, 0.64–7.58; p=0.20). Conclusions. Incident T-wave inversion was the most common newly detected ECG abnormality after kidney transplantation and was associated with pre-existing ST-segment depression and lower postoperative potassium levels. Although not independently associated with MACE, its persistent two-fold risk estimate suggests that incident T-wave inversion may represent a marker of perioperative myocardial vulnerability. Larger prospective studies are warranted to clarify whether systematic post-transplant ECG assessment improves cardiovascular risk stratification in recipients of kidney transplantation.