Alterations in heart rate variability in patients with peripheral arterial disease requiring surgical revascularization have limited association with postoperative major adverse cardiovascular and cerebrovascular events.

OBJECTIVE: Obstructive sleep apnea (OSA) is common in peripheral arterial disease (PAD) and associates with high mortality after surgery. Since abnormal heart rate variability (HRV) is predictive of postoperative complications, we investigated the relations of HRV with PAD, OSA and major adverse cardiovascular and cerebrovascular events (MACCE). MATERIALS AND METHODS: Seventy-five patients (67±9 years) scheduled for sub-inguinal revascularization and 15 controls (63±6 years) underwent polysomnography and HRV analyses. OSA with an apnea-hypopnea index (AHI) ≥20/hour was considered significant. HRV was measured during wakefulness, S2, S3-4 and rapid eye movement (REM) sleep with time and frequency domain methods including beat-to-beat variability, low frequency (LF) and high frequency (HF) power, and detrended fluctuation analysis (DFA). MACCE was defined as cardiac death, myocardial infarction, coronary revascularization, hospitalized angina pectoris and stroke. RESULTS: Thirty-six patients (48%) had AHI≥20/hour. During follow-up (median 52 months), 22 patients (29%) suffered a MACCE. Compared to controls, fractal correlation of HRV (scaling exponent alpha 1 measured with DFA) was weaker during S2 and evening wakefulness in all subgroups (+/-AHI≥20/hour, +/-MACCE) but only in patients with AHI≥20/hour during morning wakefulness. The LF/HF ratio was lower in all subgroups during S2 but only in patients with AHI ≥20/hour during evening or morning wake. In the covariance analysis adjusted for age, body mass index, coronary artery disease and PAD duration, the alpha 1 during morning wakefulness remained significantly lower in patients with AHI≥20/hour than in those without (1.12 vs. 1.45; p = 0.03). Decreased HF during REM (p = 0.04) and S3-4 sleep (p = 0.03) were predictive of MACCE. In analyses with all sleep stages combined, mean heart rate as well as very low frequency, LF, HF and total power were associated with OSA of mild-to-moderate severity (AHI 10-20/hour). CONCLUSIONS: HRV is altered in patients with PAD. These alterations have a limited association with OSA and MACCE.

Sleep apnoea is associated with major cardiac events in peripheral arterial disease.

Obstructive sleep apnoea (OSA) is associated with atherosclerosis and cardiovascular events. Peripheral arterial disease (PAD) represents severe atherosclerosis with a high mortality after vascular surgery. The role of OSA in the prognosis of these patients is not yet established. 84 patients (aged 67 ± 9 years) scheduled for sub-inguinal surgical revascularisation were enrolled for preoperative polysomnography. The threshold for significant OSA was an apnoea/hypopnoea index ≥ 20 events·h(-1). Major adverse cardiovascular and cerebrovascular events (MACCE), including cardiac death, myocardial infarction, coronary revascularisation, angina pectoris requiring hospitalisation and stroke, were used as a combined end-point. During follow-up (median 52 months), 17 out of 39 patients with and six out of 45 patients without significant OSA suffered MACCE. In the multivariate Cox regression, the primary predictors of MACCE were significant OSA (hazard ratio (HR) 5.1 (95% CI 1.9-13.9); p=0.001) and pre-existing coronary artery disease (HR 4.4 (95% CI 1.8-10.6); p=0.001). Other significant predictors were a ≥ 4 year history of PAD (HR 3.8 (95% CI 1.3-11.5); p=0.02) and decreasing high-density lipoprotein/total cholesterol ratio (HR 0.95 per percentage (95% CI 0.90-1.00); p=0.048). OSA is associated with poor long-term outcome in patients with PAD following revascularisation. OSA might have an important role in the pathogenesis of cardiovascular morbidity and mortality in these patients.

Unrecognised obstructive sleep apnoea is common in severe peripheral arterial disease.

Patients needing surgery for peripheral arterial disease (PAD) represent a severe form of atherosclerosis with an overall 5-yr mortality of 30% after revascularisation. The aetiology for poor post-operative clinical outcome in these high-risk patients is not fully established. Obstructive sleep apnoea (OSA) is associated with atherosclerosis and is an independent risk factor for fatal and nonfatal cardiac events. Here, we determine the prevalence of undiagnosed OSA in a homogenous group of PAD patients undergoing subinguinal surgical revascularisation. 82 consecutive patients (mean age 67±9 yrs, 52 males) with sinus rhythm and without congestive heart failure or previously diagnosed OSA were enrolled for pre-operative polysomnography and echocardiography. OSA was present in 70 (85%) patients (95% CI 75-93%), of whom 24 (34%) had severe OSA. OSA was mostly asymptomatic, and age- and sex-adjusted multivariate regression analysis showed no relation to obesity, metabolic syndrome or any manifestation of atherosclerosis, other than PAD. Left ventricular ejection fraction (p = 0.002) and high-density lipoprotein/total cholesterol ratio (p = 0.03) were the only independent predictors for the severity of OSA. Thus, prevalence of OSA is unexpectedly high in patients with PAD and is not related to classical risk factors of sleep apnoea.