LONDON (FRONTLINE MEDICAL NEWS) – The majority of patients with severe heart failure had sleep-disordered breathing and, in most affected patients, this manifested as obstructive sleep apnea, in an analysis of more than 1,000 German heart failure patients enrolled in a multicenter registry.

“The vast majority of heart failure patients with sleep-disordered breathing [SDB] have obstructive sleep apnea, which differs from previous results,” said Dr. Olaf Oldenburg at the annual congress of the European Society of Cardiology. Possible reasons why this German registry had different findings, compared with prior reports, were its inclusion of heart failure patients with milder symptoms, inclusion of patients with preserved ejection fraction, and inclusion of more women, suggested Dr. Oldenburg, director of the sleep laboratory at the Heart and Diabetes Center of Ruhr University of Bochum in Bad Oeynhausen, Germany.

His finding that nearly two-thirds of the heart failure patients with SDB in this registry had obstructive sleep apnea and that one-third had moderate or severe obstructive sleep apnea was notable because this remains a form of sleep-disordered breathing that can be treated, he said. “There is still enough evidence to treat obstructive sleep apnea” in heart failure patients when it has a moderate or severe presentation, which is defined as causing 15 or more apnea-hypopnea events/hour during sleep. “Obstructive sleep apnea is definitely not a compensatory mechanism in heart failure,” Dr. Oldenburg said.

He highlighted the ongoing need to treat more severe obstructive sleep apnea in heart failure patients because this form of SDB sharply contrasts with the results of the SERVE-HF trial, also reported at the congress, which showed that in patients with advanced heart failure and central sleep apnea nocturnal treatment with adaptive servo ventilation failed to provide benefit and also appeared to boost patient mortality ( N Engl J Med. 2015 Sep 17;373[12]:1095-105 ).

Following that report “we need to think about which heart failure patients to treat” with nocturnal ventilation, and differentiate between heart failure patients with obstructive sleep apnea and those with central sleep apnea, Dr. Oldenburg said.

The data he reported came from the SchlaHF-XT (Sleep Disordered Breathing in Heart Failure)registry, which enrolled patients with heart failure and reduced or preserved ejection fraction and any New York Heart Association functional class treated either at German hospitals or in physician offices. He reported data for 1,186 fully assessed and classified patients, who averaged 68 years old and two-thirds of whom were men. Slightly more than half had heart failure with reduced ejection fraction, and about half had New York Heart Association class II heart failure, a quarter had class III heart failure, with the remaining patients divided roughly equally between class I and IV.

Screening for SDB showed that 24% had no SDB, 37% had mild SBD, 21% had moderate SDB, and 19% had severe SDB (percentages total 101% because of rounding). Among those with SDB, 64% had obstructive sleep apnea, 22% had central sleep apnea, and the remaining 14% had either a mixed form of sleep apnea or were not classifiable.

The analysis also showed that moderate and severe SDB, the forms that require treatment, occurred more often among patients with heart failure and reduced ejection fraction, 43%, compared with patients with heart failure and preserved ejection fraction, who had a 36% prevalence of SDB requiring treatment. Moderate or severe central sleep apnea occurred in 15% of patients with reduced ejection fraction and in 9% of patients with preserved ejection fraction.

A second report at the congress by Dr. Oldenburg showed that the duration of time when a patient’s oxygen saturation fell below 90% was a better gauge of the severity of SDB than was the traditional measure of the apnea-hypopnea index (AHI), the average number of apnea-hypopnea episodes a patient has during an hour of sleep. For this analysis, he used data collected on 963 patients with chronic, stable heart failure with reduced ejection fraction who underwent a comprehensive sleep study with pulse oximetry measurements during 2002-2013.

The results showed that while the measured AHI significantly linked with the 5-year mortality rate of these patients, the relationship became statistically insignificant after researchers adjusted for age, sex, body mass index, heart failure severity, ejection fraction, medications, and other clinical variables.

In contrast, the average time a patient spent with an oxygen saturation level below 90% overnight strong linked with 5-year mortality even after adjusting for all these covariables. The analysis showed that each hour of sleep a heart failure patient spent with an oxygen saturation level below 90% linked with a relative 16% reduction in 5-year survival. Patients in the quartile with the greatest amount of time spent with a oxygen saturation level below 90% had a 50% 5-year mortality rate, while those in the quartile with the least amount of time spent with severely depressed oxygen saturation had a 30% 5-year mortality rate.

Based on this finding “you need to look at the effect of SDB and not just the apnea-hypopnea index” when assessing SDB in patients with heart failure, Dr. Oldenburg said.

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