CPAP could help prevent heart failure in sleep apnea patients
MedWire News: Nightly treatment with a continuous positive air pressure (CPAP) device in obstructive sleep apnea (OSA) patients could prevent cardiac changes that lead to heart failure (HF), research shows.
Gregory Lip (University of Birmingham Centre for Cardiovascular Sciences, UK) and colleagues found that moderate-to-severe OSA caused changes in the structure and function of the heart that were characteristic of hypertension. However, after 6 months of CPAP treatment, these abnormalities returned to near-normal measurements.
"To the best of our knowledge, this is the first study to provide a comprehensive assessment of left ventricular (LV) structural and functional parameters using advanced echocardiograms in otherwise healthy apnea patients," commented Lip in a press statement.
Using two-dimensional echocardiography, tissue Doppler imaging, and three-dimensional echocardiography, the researchers evaluated LV function in 40 patients with moderate-to-severe OSA (Apnea-Hypopnea Index>15, diagnosed by multichannel polysomnography), 40 patients with essential hypertension but otherwise healthy), and 40 healthy controls.
Septal and posterior wall thickness, LV mass index, LV volume and ejection fraction, as well as mitral valve inflow indices (early inflow peak velocity [E], late inflow peak velocity [A]), were assessed in all patients.
OSA patients were treated with CPAP for at least 4 hours per night for more than five nights per week. The mean duration of 26 weeks of CPAP therapy was completed by 37 OSA patients, after which their echocardiographic parameters were reassessed.
Posterior wall thickness and LV mass index were significantly higher in the OSA and hypertensive groups, at 1.2 cm for both, compared with the healthy group, at 1 cm (p<0.0001).
Systolic 'S' velocity was significantly reduced in OSA and hypertensive patients, at 6 cm/s for both, compared with 7 cm/s in healthy patients (p<0.0001).
Acute diastolic function parameters, including E/A, isovolumetric relaxation time, and E/septal E', indicated diastolic impairment in both OSA and hypertensive groups, compared with healthy patients.
Mean left atrial volume index as measured by three-dimensional echocardiography was significantly greater in the OSA and hypertensive groups, at 26.3 ml/m2 and 23.1 ml/m2, respectively, than in the healthy group, at 18.2 ml/m2 (p<0.0001).
"In OSA patients, CPAP therapy resulted in reduction of the posterior wall thickness and improvement in LV ejection fraction, systolic 'S' velocity, and diastolic LV impairment," say the authors.
"OSA patients may have cardiac abnormalities that often are undetected, but will improve with CPAP," said Lip. "Patients also need to understand that OSA is not a benign disorder, but that their risk of heart problems can be easily treated with CPAP."
Physicians should question patients with hypertension and/or abnormal echocardiograms about snoring and other signs of sleep apnea, although asking their partners is more reliable, Lip added.
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By Piriya Mahendra