Abstract 2309: Patients with Severe Sleep Apnea have Increased and Altered Sleep Stage Distribution of Ventricular Premature Contraction Frequency
Sudden cardiac death in obstructive sleep apnea patients was recently shown to cluster during sleep, unlike after waking in the general population. We hypothesized that VPCs and autonomic markers would be worse during sleep in apneic patients.
Methods: Patients with CAD but no heart failure and no prior diagnosis of sleep apnea were studied (n=126) in a sleep laboratory. Heart rate turbulence parameters turbulence slope (TS) and onset (TO) were studied both with and without correction for VPC count.
Results: Apnea/hypopnea index (AHI) was > 15 (apneic) in 51, <15 (control) in 75 patients. Apneic patients spent more time in the S1 sleep stage (p<0.0001) and less time in deeper and Rem sleep stages, in absolute time and % time asleep. Apneic patients had similar heart rate (mean RR=949 ± 14 (s.e.m.) vs 972 ± 13 ms, p=0.22), but more VPCs in count (7.5 ± 1.1 vs 3.0 ± 0.5 per sleep stage, p< 0.0001) and in frequency (0.110 ± 0.012 vs 0.044 ± 0.005 VPCs/min, p< 0.0001) compared to control. A histogram that tallied sleep stage ordering by VPC frequency for each patient (see figure⇓) suggested that in apneic patients, VPCs were most frequent in Rem, while in control patients VPCs were most frequent in Wake. TS and TO were not correlated with AHI studied as a continuous variable. TS was reduced in AHI>30 compared to AHI<30 (3.8 IQR 5.1 vs 7.8 IQR 9.7, p<0.01) but TO was not (−1.0 IQR 3.3 vs −1.8 IQR 3.3, p=0.09). There were no differences in TS and TO over the different sleep stages.
Conclusion: VPCs are more frequent in severe sleep apnea, and appear to have a different distribution over the sleep stages from absent/mild sleep apnea patients, which may cause the sleep time propensity to sudden death in sleep apnea patients.