Obstructive sleep apnoea in acute coronary syndrome: the invisible threat?

The Long-Term Prognostic Role of Nighttime Resting Heart Rate in Obstructive Sleep Apnea in Patients with Acute Coronary Syndrome

AIM

A close relationship exists between resting heart rate (RHR) and obstructive sleep apnea (OSA). Still, the prognostic importance of nighttime RHR in patients with acute coronary syndrome (ACS) with or without OSA remains unclear.

METHODS

In this prospective cohort study, OSA was defined as an apnea-hypopnea index of ≥ 15 events/h, and the high nighttime RHR (HNRHR) was defined as a heart rate of ≥ 70 bpm. The primary endpoint was a major adverse cardiovascular and cerebrovascular event (MACCE), including cardiovascular death, myocardial infarction, stroke, ischemia-driven revascularization, or hospitalization for heart failure.

RESULTS

Among the 1875 enrolled patients, the mean patient age was 56.3±10.5 years, 978 (52.2%) had OSA, and 425 (22.7%) were in HNRHR. The proportion of patients with HNRHR is higher in the OSA population than in the non-OSA population (26.5% vs. 18.5%; P＜0.001). During 2.9 (1.5, 3.5) years of follow-up, HNRHR was associated with an increased risk of MACCE in patients with OSA (adjusted HR: 1.56, 95% CI: 1.09-2.23, P=0.014), but not in patients without OSA (adjust HR: 1.13, 95% CI: 0.69-1.84, P=0.63).

CONCLUSIONS

In patients with ACS, a nighttime RHR of ≥ 70 bpm was associated with a higher risk of MACCE in those with OSA but not in those without it. This identifies a potential high-risk subgroup where heart rate may interact with the prognosis of OSA. Further research is needed to determine causative relationships and confirm whether heart rate control impacts cardiovascular outcomes in patients with ACS-OSA.

Influence of Obstructive Apnea Index on Persistent Left Ventricular Dysfunction in Patients with ST-Segment Elevation Myocardial Infarction

Background: We retrospectively investigated the effects of the severity and classification of sleep-disordered breathing (SDB) on left ventricular (LV) function in patients with ST-segment elevation myocardial infarction (STEMI). Methods: A total of 115 patients with STEMIs underwent a sleep study using a multichannel frontopolar electroencephalography recording device (Sleep Profiler) one week after STEMI onset. We evaluated LV global longitudinal strain (LV-GLS) using two-dimensional echocardiography at one week and seven months. Patients were classified as no SDB (AHI < 5 events/h), obstructive SDB (over 50% of apnea events are obstructive), and central SDB (over 50% of apnea events are central). Due to the device's limitations in distinguishing obstructive from central hypopnea, SDB classification was based on apnea index percentages. Results: The obstructive apnea index (OAI) was significantly associated with LV-GLS at one week (r = 0.24, p = 0.027) and seven months (r = 0.21, p = 0.020). No such correlations were found for the central apnea index and SDB classification. Multivariable regression analysis showed that the OAI was independently associated with LV-GLS at one week (β = 0.24, p = 0.002) and seven months (β = 0.20, p = 0.008). Conclusions: OAI is associated with persistent LV dysfunction assessed by LV-GLS in STEMI.

Relation of Age to Survival in Patients with Obstructive Sleep Apnea who Develop an Acute Coronary Event (from the National Inpatient Sample)

This study was undertaken to investigate whether obstructive sleep apnea (OSA) produces a survival advantage in acute coronary syndrome (ACS), and to evaluate the mechanism of any benefit, including the impact of age and other risk factors. The National Inpatient Sample was queried for all patients who were admitted for ACS during the years 2013 to 2014. The primary outcomes were all-cause in-hospital mortality and cardiogenic shock (CS). Multivariable logistic regression was used for analysis. A total of 1,080,340 patients with ACS were included, 63,255 patients had OSA. The majority of patients were males (60.3%) and of Caucasian race (75%). The mean age was 67 years (SEM: 0.1). Despite a higher burden of risk factors and older age, OSA patients had a lower risk for mortality and cardiogenic shock adjusted OR 0.68 (95%CI 0.61-0.75), p <0.001 and 0.81 (95%CI: 0.74 to 0.89), p <0.001 respectively. Age was an important effect modifier. Survival advantage and lower risk for CS arises at the age above 55 and become more apparent with increasing age. In conclusion, despite a higher CV risk profile, and older age, OSA produces a survival benefit in ACS. Age is a significant modifier of risk in OSA patients with ACS. Ischemic preconditioning might explain these results.