Brown, Jason2018-01-102018-01-102017-10https://hdl.handle.net/11299/192681University of Minnesota Ph.D. dissertation. October 2017. Major: Epidemiology. Advisor: Alvaro Alonso. 1 computer file (PDF); vii, 117 pages.Heart failure (HF) is a major public health burden, with over 6.5 million adults in the US suffering from the disease. Moderate to advanced-stage heart failure patients implanted with cardiac resynchronization therapy (CRT) devices suffer from increased mortality risk and frequent inpatient hospitalization. Efforts to reduce mortality and prevent HF-related hospitalizations in this population would be of significant benefit to the patients, as well as to the health care system. In this doctoral dissertation, we present three manuscripts examining associations between CRT device-measured and device-programmed parameters and patient mortality and HF-hospitalization. In the first manuscript, we examined the device-measured parameter of intrathoracic impedance, and whether an OptiVol® threshold crossing or time above OptiVol® threshold were associated with patient mortality and HF-related hospitalization. We found that patients with >15.1% of their follow-time above threshold had a 4.2 times greater risk of mortality and a 3.2 times greater risk of HF-hospitalization than those patients with <4.1% of follow-up time above threshold. In addition, a single OptiVol® crossing was associated with an 87% higher mortality rate, and a 70% higher HF-hospitalization rate. In the second manuscript, we examined the device-measured associations between biventricular pacing percentage, AF burden, and heart rate variability on patient mortality and HF-related hospitalization. We found a complex relationship between biventricular pacing percentage, AF, AVN ablation, and HRV where patients with <99% bi-V pacing percentage had an increased rate of mortality and hospitalization among those with no baseline device-measured atrial fibrillation. In addition, AVN ablation was associated with worse outcomes among those with high baseline HRV, suggesting that the potential loss of benefits of higher HRV must be weighed when performing an AVN ablation procedure. The third manuscript looked at parameters associated with an increased risk of 30-day HF-related rehospitalization. We found that parameters associated with kidney function to be of critical importance in evaluating the risk of patients at higher risk of rehospitalization within 30 days. Patients with a daily intrathoracic impedance measurement >8less than the reference impedance value on the day of discharge, a diagnosis of chronic kidney disease, no diuretic prescription, male sex, longer duration of heart failure at the time of index hospitalization, and those with a prior CABG procedure to have a higher risk of 30-day rehospitalization. Model AUC, NRI, IDI, and Hosmer-Lemeshow statistics indicated good model discrimination with respect to a previously published model with good calibrationenCardiac resynchronization therapyHeart failureImplantable cardioverter-defibrillatorIntrathoracic impedanceRehospitalizationThesis or Dissertation