The study was designed to determine the effectiveness of adaptive servo ventilation (ASV) in treating patients who developed sleep disordered breathing as a result of systolic heart failure.
ASV is a variation on CPAP that uses computerized monitoring to detect variations in a patient’s breathing, and only turn on air pressure when breathing lessens.
In this study, 1325 chronic heart failure patients whose hearts were not pumping efficiently were assigned to receive regular treatment for their condition or else get regular treatment with ASV. The primary endpoint being measured was a combination of all cause mortality, worsening heart failure, or life-saving cardiovascular intervention. Overall, there was no difference in the primary endpoint. Nor did people experience improvements in quality of life, the ability to walk further, and subjective symptoms.
But there was a difference in all-cause mortality, with about 35% of the ASV group dying in the average of 31 months of follow-up, compared to only about 29% for the control group. Cardiovascular mortality showed a similar difference, with 30% of patients in the ASV group dying, compared to only 24% in the control group.
These results contradicted earlier, smaller trials. In response to them, researchers noted that perhaps central sleep apnea is actually a compensation mechanism that actually helps heart failure patients and overwhelming it with forced air could therefore be damaging.
Continued Study Is Necessary
Beyond the clinical insight for this group of heart failure patients, this study reminds us that we don’t really understand sleep apnea. instead, it’s vital that we continue to research the topic.
And in the meantime, it’s important that patients understand that there are a range of sleep apnea treatment options available, and that people respond differently to them.