Admission heart rate affects in-hospital mortality for heart failure patients
medwireNews: A heart rate above and below a certain threshold was independently associated with higher rates of in-hospital mortality, show study findings.
Specifically, the lowest rates of in-hospital mortality occurred between heart rates of 70 to 75 beats per minute (beat/min), with heart rates above and below this range being associated with an increase in mortality mainly due to chronic heart failure (HF).
"To the best of our knowledge," write Gregg Fonarow (UCLA Medical Center, California, USA) and colleagues, "this is the first study to demonstrate a J-shaped relationship between mortality and heart rate in acute HF independent of known patient and hospital factors."
The study team examined almost 150,000 admissions between January 2005 and September 2011 for HF at 295 hospitals that took part in a program evaluating the association of admission heart rate with in-hospital outcomes.
Among the admitted patients, 77,850 had information on their presenting heart rhythm available with 68.6% being in sinus rhythm (SR) and 31.4% having/in atrial fibrillation (AF).
An analysis showed increased odds of in-hospital mortality per 10 beat/min increase in heart rate above 70 beat/min according to both an unadjusted and an adjusted analysis.
Mortality risk persisted to a lesser degree when the heart was above 105 beat/min upon admission and it incrementally declined as a patients' presenting heart rate approached 70 beat/min from either direction.
Overall, patients who presented in AF had a higher mortality (4.1%) than those in SR (2.6%). Furthermore, the mortality curve for AF patients plateaued when the heart rate reached above 105 beat/min, while mortality continued to rise for patients in SR above this rate.
"It may be that heart rates above 105 in patients with AF reflect the arrhythmia alone and not the underlying HF disease state," explain authors in the American Heart Journal. "Alternatively, this finding may reflect that these are the patients who receive more aggressive therapy to lower their heart rate acutely, which in turns improves their prognosis."
The authors point out that the nature of the relationship between heart rate and mortality is still being researched and say that better understanding is still at an early stage.
"Whether early reduction of heart rate will improve short-term outcomes in patients hospitalized with HF is worthy of further investigation," they conclude.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Peter Sergo, medwireNews Reporter