Sleep apnea detection by a cardiac resynchronization device integrated thoracic impedance sensor: A validation study against the gold standard polysomnography

<div><p>Background</p><p>Sleep disordered breathing is a common but often undiagnosed comorbidity in heart failure patients. Cardiac implantable electronic devices used for cardiac resynchronization therapy (CRT) may detect sleep apnea by use of a transthoracic impedance sensor. Validation of the AP scan® algorithm (Boston Scientific®) was performed by using the diagnostic gold standard polysomnography (PSG).</p><p>Methods</p><p>Forty-one patients with impaired left ventricular ejection fraction, frequent right ventricular pacing due to atrioventricular block and heart failure symptoms despite optimal medical therapy underwent upgrading to biventricular pacing. Within one month after left ventricular lead implantation, sleep apnea was assessed by single-night PSG and AP scan® measurements.</p><p>Results</p><p>AP scan® measurements were valid in only 21 of 41 (51.2%) patients in the index night of the PSG. The PSG determined apnea-hypopnea index did not correlate statistically significant with the AP scan® measurements (r = 0.41, 95% confidence interval -0.05–0.72, p = 0.07). The degree of overestimation is displayed by using the Bland-Altman method: mean difference -12.4, standard deviation ± 15.8, 95% confidence interval -43.3–18.6.</p><p>Conclusions</p><p>In heart failure patients receiving CRT upgrading, the AP scan® algorithm may need further improvement before it can be recommended for sleep apnea detection.</p></div

Bland-Altman plot (y axis: Difference between PSG-AHI and AP scan® measurements in the index night; x axis: Mean of the AP scan® and PSG-AHI), showing mean of the differences (bias) presented with the 95% confidence interval.

<p>Bland-Altman plot (y axis: Difference between PSG-AHI and AP scan® measurements in the index night; x axis: Mean of the AP scan® and PSG-AHI), showing mean of the differences (bias) presented with the 95% confidence interval.</p

Bland-Altman plot (y axis: Difference between PSG-AHI and AP scan® measurements in the index night; x axis: Mean of the AP scan® and PSG-AHI), showing mean of the differences (bias) presented with the 95% confidence interval.

<p>Bland-Altman plot (y axis: Difference between PSG-AHI and AP scan® measurements in the index night; x axis: Mean of the AP scan® and PSG-AHI), showing mean of the differences (bias) presented with the 95% confidence interval.</p

Baseline charcteristics of the study cohort and sleep disordered breathing evaluated by single-night PSG.

<p>Baseline charcteristics of the study cohort and sleep disordered breathing evaluated by single-night PSG.</p

Bland-Altman plot (y axis: Difference between PSG-AHI adjusted to the night hours programmed and AP scan® measurements in the index night; x axis: Mean of the AP scan® and PSG-AHI), showing mean of the differences (bias) presented with the 95% confidence interval.

<p>Bland-Altman plot (y axis: Difference between PSG-AHI adjusted to the night hours programmed and AP scan® measurements in the index night; x axis: Mean of the AP scan® and PSG-AHI), showing mean of the differences (bias) presented with the 95% confidence interval.</p

Scatter plot between AP scan® measurements and the AHI evaluated by PSG (in events/h).

<p>Scatter plot between AP scan® measurements and the AHI evaluated by PSG (in events/h).</p

CONSORT diagram of the UPGRADE study.

<p>CONSORT diagram of the UPGRADE study.</p