Incident Hemodialysis Electrolyte Analysis and Rhythm Trends (IHEART) - Project Summary/Abstract This R03 award will contribute to providing Dr. Katherine Ravi with the resources, additional training and protected time necessary to achieve her goal of becoming an independent clinical investigator. Dr. Ravi has completed her Master of Public Health and will continue to benefit from her outstanding institutional support and resources through the pursuit of didactic courses for continued formal education in biostatistics and study design through Harvard Catalyst and the Harvard Master of Medical Sciences in Clinical Investigation program, research conferences, leadership courses and training in the responsible conduct of research. These will complement her strong institutional support and will build upon her prior training in human investigation. Well over a million patients have initiated hemodialysis in the last decade in the United States alone, and their mortality rate during their first year on hemodialysis is nearly 20%. The risk of death is particularly high in the first 120 days after starting hemodialysis, with cardiac arrest of unknown cause occurring at a rate of 5.2 per 100 person-years during this period. It has been demonstrated that the first week of hemodialysis is associated with the highest rate of cardiovascular events. However, few studies have assessed cardiac rhythms during the particularly vulnerable hemodialysis initiation period. This R03 proposal (PAR-22-129), entitled “Incident Hemodialysis Electrolyte Analysis and Rhythm Trends (IHEART)” will investigate how cardiac rhythm morphology associated with sudden cardiac death evolves during the early stages of hemodialysis, and how serum electrolyte levels are associated with these changes. We will perform a cohort study on 30 patients initiating hemodialysis; we will recruit 33 patients total to allow for a 10% dropout rate. In Aim 1, we will compare QTc duration, ventricular ectopy, heart rate variability (all markers of sudden cardiac death and arrhythmia risk) and arrhythmia in week 1 and week 5 of hemodialysis initiation. In Aim 2, we will assess how electrolytes are associated with these changes, with a focus on ionized calcium levels. During this award period, Dr. Ravi will employ her excellent academic resources and mentorship at Brigham and Women’s Hospital to continue in her pursuit of skills and expertise required to attain R01 funding, allowing her to continue her critically important research and to train future clinical investigators.