Heart rate variability parameters among acute heart failure patients in a tertiary center in Nigeria

The morbidity and mortality associated with heart failure remain high despite advancement in its management hence underscoring the need for further detection of factors contributing to poor outcome. Heart rate variability (HRV) has been shown to predict outcomes in various cardiovascular disease and sudden cardiac death (SCD). This study therefore, was designed to define the relationship between 24-hour Holter electrocardiographic parameters at admission and the outcome of hospital admission among acute heart failure patients. The study was a hospital-based prospective cohort study. One hundred and fifty subjects with acute heart failure and same control subjects were recruited. All participants had clinical evaluation with 24 hours Holter ECG and Echocardiographic studies. Recruited subjects were closely monitored throughout the hospital admission period for clinical events. The outcomes of hospital admission were determined and documented accordingly. One hundred and forty cases and one hundred and forty controls were eventually analyzed. The mean ages of both cases and controls were similar, likewise their sex distribution and other anthropometric parameters. Heart rate variability analysis showed that proportion of R-R interval that differs by more than 50msec (pNN50) was significantly lower among in-hospital deaths compared to survivors. Also, at 30-days post discharge, both pNN50 and standard deviation of normal to normal R-R intervals (SDNN) were significantly lower among patients that died than in those that survived. There was weak positive correlation between Heart rate variability and myocardial systolic functions, while there was stronger negative correlation with diastolic functions.