(20) Evaluate how OSA affects development of left ventricular diastolic abnormalities and if CPAP improves such alterations. 27 middle-aged OSA men with neither controllable factors nor conditions affecting left ventricular diastolic function and 15 healthy control subjects were selected. OSA patients were randomized to 12 weeks on sham CPAP and 12 weeks on effective CPAP application. Abnormal left ventricular filling pattern was present in 15 of the 27 OSA patients and only in 3 of the 15 control subjects. OSA patients, 12 weeks on effective CPAP induced a significant increase in E/A ratio, as well as reductions in mitral deceleration and isovolumic relaxation times. Study demonstrated increased risk for development of left ventricular diastolic abnormalities in OSA patients and showed CPAP significantly reduced symptoms.
Atrial Fibrillation (AF):
(21) Study aimed to determine prevalence of nocturnal cardiac arrhythmias in patients with sleep disordered breathing. 228 subjects with sleep-disordered breathing 338 subjects without were evaluated. AF, nonsustained ventricular tachycardia, and complex ventricular ectopy were more common in subjects with sleep-disordered breathing compared with those without.
(22) Study aimed to determine prevalence of OSA in AF patients. Researchers prospectively studied consecutive patients undergoing electrocardioversion for AF (n=151) and consecutive patients without past or current AF referred to a general cardiology practice (n=312). OSA was diagnosed with the Berlin questionnaire and a subgroup was evaluated with PSG for accuracy. The proportion of patients with OSA was significantly higher in the AF group than in the general cardiology group (49% versus 32%).
(23) Evaluated left atrial diameter and arterial stiffness in patients with OSA. 73 middle-aged subjects were divided in two groups: with moderate-to-severe OSA (AHI ≥15) or without OSA (AHI≤5). pulse wave velocity and left atrial diameter were significantly increased in patients with OSA. Pulse wave velocity significantly correlated with left atrial diameter.
(24) Study aimed to determine whether patients with OSA have an abnormal atrial substrate. 40 patients undergoing ablation of paroxysmal AF and in sinus rhythm (20 with OSA [AHI ≥ 15] and 20 with no OSA [AHI < 15] were studied. OSA is associated with significant atrial remodeling characterized by atrial enlargement, reduction in voltage, site-specific and widespread conduction abnormalities, and longer sinus node recovery.
(25) Study aimed to evaluate the efficacy of CPAP therapy on recurrences of AF after ablation. This study prospectively included 153 patients (128 men; 60±9 years) who underwent extensive encircling pulmonary vein isolation for drug refractory AF. PSG was preformed one week after ablation. Of 153 patients, 116 patients were identified as having OSA. Data regarding the use of CPAP and recurrences of AF were obtained in 82 patients. The remaining 34 patients with OSA were defined as the no-CPAP group. Patients with untreated OSA have a higher recurrence of AF after ablation. Appropriate treatment with CPAP in patients with OSA is associated with a lower recurrence of AF.
(26) This study was a meta‐analysis and found that in OSA patients treated with CPAP, the AF recurrence risk following catheter ablation was not significantly different from a control population without OSA, whereas OSA patients not treated with CPAP had a statistically significant 57% increased risk of recurrence.
28 Other Arrhythmias:
(27) Study aimed to determine severity of arrhythmias in OSA patients and evaluate benefit of CPAP therapy. 23 patients (16 men, 50±11 years) with moderate and severe OSA were included. Approximately half of OSA patients evidence severe cardiac rhythm disturbances, which are significantly reduced by CPAP.
(28) Review article discussing how OSA is associated with a significantly higher overall risk of complex ventricular ectopy, defined as nonsustained ventricular tachycardia, bigeminy, trigeminy, or quadrigeminy (25% versus 14.5%). An increased risk of sudden cardiac death has been reported in patients with severe OSA, particularly among those observed to have nocturnal oxygen desaturation to <78%. 29 - 37 Other Forms of Cardiovascular Disease: (29) Study determined if OSA in associated with increased risk of stroke. A total of 5,422 participants without a history of stroke at the baseline examination and untreated for sleep apnea were followed for a median of 8.7 years. One hundred ninety-three ischemic strokes were observed. There was a strong adjusted association between ischemic stroke and obstructive apnea–hypopnea index in community-dwelling men with mild to moderate sleep apnea. (30) Study aimed to evaluate the microcirculation in OSA. This study included seven patients with OSA and seven control subjects (mean age, 38 yr). Patients with OSA with low cardiovascular risk status had increased oxidant production (oxidative stress) in the microcirculation and endothelial dysfunction. (31) Study aimed to determine whether treatment of OSA with CPAP would favorably alter coagulability across the sleep–wake cycle. 28 patients received therapeutic or placebo CPAP, each for 2 months with a 1 month washout between treatments. Treatment of OSA with CPAP reduced the early morning level of vWF, and nocturnal levels of FVIII and FV. These findings suggest that CPAP may reduce cardiovascular risk in OSA, in part through reducing risk of thrombosis. (32) This study aimed to evaluate the effect of treating OSA on the rate of cardiovascular events in coronary artery disease (CAD). Researchers prospectively studied 54 patients (mean age 57.3 years) with both CAD and OSA (AHI ⩾15). In 25 patients, OSA was treated with CPAP (n=21) or upper airway surgery (n=4), the remaining (n=29) declined treatment. Treatment of OSA in CAD patients was associated with a decrease in the occurrence of new cardiovascular events (33) Study aimed analyze the independent impact of long-term CPAP treatment on mortality in patients with ischemic stroke. Prospective observational study in 166 patients with ischemic stroke. PSG was conducted in all of them and CPAP treatment was offered in the case of moderate to severe cases (>15 AHI). Patients were followed-up for 5 years to analyze the risk of mortality. Long-term CPAP treatment in moderate to severe OSA and ischemic stroke is associated with a reduction in excess risk of mortality.
(34) Study aimed to determine mortality in patients with sleep apnea/hypopnea syndrome (SAHS) according to the treatments employed and comorbidity. A total of 475 SAHS patients, 444 (94%), with a mean AHI diagnosis of 55, were located and included in the study. a rise in mortality was found in nontreated sleep apnea/hypopnea syndrome patients compared with the general population, whereas mortality in those treated for sleep apnea/hypopnea syndrome did not differ significantly from that of the general population.
(35) Study aimed to evaluate the effect of OSA on cardiovascular risk for patients with different acute coronary syndrome phenotypes. This study included 1,701 patients admitted for ACS. To evaluate the presence of OSA (AHI ≥ 15), all patients underwent polygraphy. For patients with ACS and a specific phenotype, OSA is associated with an increased risk of recurrent cardiovascular events.
(36) Study evaluated the association between obstructive sleep apnea and 30-day risk of cardiovascular complications after major noncardiac surgery. Prospective cohort study involving adult at-risk patients without prior diagnosis of sleep apnea and undergoing major noncardiac surgery from 8 hospitals in 5 countries between 2012 and 2017. 1218 patients (mean age, 67; 40.2% women) were included. Among at-risk adults undergoing major noncardiac surgery, unrecognized severe obstructive sleep apnea was significantly associated with increased risk of 30-day postoperative cardiovascular complications.
(37) Study aimed to ascertain whether objectively measured OSA independently increases the risk of all cause death, cardiovascular disease (CVD), coronary heart disease (CHD), stroke or cancer. Researchers evaluated follow-up data in 397 people. There were 77 deaths, 103 cardiovascular events (31 strokes, 59 CHD) and 125 incident cases of cancer (39 cancer fatalities) during 20 years follow-up. Moderate-to-severe sleep apnea was independently associated with a large increased risk of all-cause mortality, incident stroke, and cancer incidence and mortality in this community-based sample."