The relationship between serum potassium levels and cardiac arrhythmias in left ventricular assist device (LVAD) recipients: a comprehensive analysis and prognostic evaluation.

Background: This study aimed to comprehensively analyze the relationship between serum potassium (K⁺) levels and the risk of de novo cardiac arrhythmias in left ventricular assist device (LVAD) recipients.

Methods: We performed a retrospective study using the INTERMACS registry. Data was collected on adult patients with available K⁺ measurements taken 1-month post-LVAD implantation. K⁺ levels were the main exposure of interest and were analyzed as a continuous and categorical variable (quartiles of baseline K⁺ distribution). The main outcome of interest was the occurrence of de novo arrhythmia events, either sustained (ventricular [VA] or supraventricular arrhythmia [SVA]) or not sustained (atrial fibrillation/flutter [AF]). All-cause mortality was evaluated as the secondary outcome. Multivariable adjusted time-dependent Cox regression models and natural splines were used to describe the relationship between the exposure and outcomes of interest.

Results: 10,570 patients met our inclusion criteria. A significant and consistent relationship was observed between the lowest quartile of longitudinal K⁺ and the risk of arrhythmic events (HR 1.28, 95% CI 1.08, 1.53, p = 0.005) as well as in the highest K⁺ quartile (HR 1.24, 95% CI 1.02, 1.49, p = 0.027). A similar relationship was confirmed in the stratified analysis of arrhythmia types for SVAs and AF. The data were reflected in a U shaped relationship. Similarly, the highest and lowest quartiles of longitudinal K⁺ were independently associated with a significant increase in the HR of death, which was reflected by a U shaped relationship.

Conclusions: Our study reveals a significant U shaped relationship between low and high K + levels and cardiac arrhythmias in LVAD patients, particularly SVAs and AF. Both high and low K + levels negatively impacted patient survival.