#2814 Characterization of cardiological manifestations in patients with sodium-wasting tubulopathies

Abstract

Abstract Background and Aims Bartter (BS) and Gitelman (GS) syndromes are rare tubulopathies caused by mutations affecting renal NaCl transporters, resulting in similar symptoms like muscle weakness, cramps, and electrolyte imbalances, with GS also presenting with hypomagnesemia. Treatment focuses on electrolyte and fluid balance, using supplements and drugs to inhibit prostaglandin production and RAAS activation. Electrolyte deficits in these conditions can extend the QT interval and increase the risk of potentially fatal cardiac arrhythmias. This study aims to profile BS and GS patients followed at our hospital, focusing on cardiological phenotyping. We assessed diagnostic, clinical, and lab data, particularly examining the link between electrolyte imbalances (like hypokalemia or hypomagnesemia) and electrocardiographic changes or cardiac symptoms during follow-up. Method We screened all BS and GS patients for study inclusion, requiring a genetic diagnosis with disease-causing mutations and comprehensive clinical and electrocardiographic data. We excluded cases lacking sufficient data. We gathered demographic and health information retrospectively, categorizing patients based on electrocardiographic results into groups: 1) persistent long QT interval, 2) transient long QT interval, and 3) no long QT interval. Data were summarized with medians, interquartile ranges, and frequencies. Results A total of 27 patients were enrolled in the study, 16 with Bartter Syndrome (BS) and 11 with Gitelman Syndrome (GS); median length of follow-up was 6 years (range 3-19). Only one patient was classified in group 1, with a constant QTc prolongation (446.3 ms); 8 patients (34.8%) fell into group 2 with median QTc values of 420 ms, all exhibiting hypokalemia and hypomagnesemia. The majority (14/23, 61%) were in group 3, with a median QTc of 399.2 ms and 79% displaying hypokalemia and hypomagnesemia. All 9 patients who experienced cardiac-related symptoms were adults, with 8 presenting these symptoms during intercurrent episodes. The study also compared clinical differences between BS and GS patients, noting a higher frequency of hypokalemia and hypomagnesemia in GS, whereas BS patients had more electrocardiographic alterations, although not statistically significant. No echocardiographic abnormalities were detected from the available data, and there were no recorded incidents of malignant arrhythmias or sudden death. Conclusion Electrocardiographic abnormalities in BS and GS patients fluctuate, often related to episodic events, with QT prolongation in one-third of cases but no severe cardiac complications, indicating a generally positive prognosis.