ISAACC trial: CPAP controls blood pressure in ACS patients with severe OSA

A post-hoc analysis of the multicentre, randomised controlled ISAACC trial demonstrated that, in patients with acute coronary syndrome (ACS) with severe obstructive sleep apnoea (OSA), secondary hypertension can be well managed by continuous positive airway pressure (CPAP).

The main objective of the multicentre, open-label, parallel group, randomised controlled ISAACC trial (NCT01335087) was to determine whether CPAP treatment is able to reduce the incidence of cardiovascular events (i.e.cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, hospitalisation for heart failure, and hospitalisation for unstable angina or transient ischaemic attack) in patients with ACS and OSA. The primary purpose of the current post-hoc analysis, presented by Dr Manuel Sánchez De La Torre (Lleida Biomedical Research Institute, Spain), was to determine the long-term effects on blood pressure; the results were recently published [1,2].

The analysis included 1,803 patients who were admitted to hospital for ACS symptoms and underwent respiratory polygraphy during the first 24–72 hours after admission. Patients with OSA (apnoea-hypopnea index [AHI] ≥15 events/hour) were randomised 1:1 to CPAP treatment plus usual care (CPAP group) or usual care alone by a computerised system available 24 h/day. A group of patients with ACS but without OSA was also included as a reference group.

The patients received respiratory polygraphy and were stratified by their OSA: patients without OSA (n=596), those receiving usual care/poor CPAP adherence (n=978), and those with good CPAP adherence (n=229). The patients were followed for 1–5 years and blood pressure was measured at each office visit. About half of all patients (52%) had baseline hypertension.

After a median follow-up of 41 months, changes in blood pressure were similar between OSA and non-OSA groups. However, the research team observed an increase in blood pressure in the third tertile of the AHI (AHI >40 events/h) with a maximum difference in mean blood pressure of +3.3 mmHg at 30 months. OSA patients with good CPAP adherence (≥4 hours/night) had a reduced mean blood pressure after 18 months compared with usual care/poor CPAP adherence patients, a maximum mean difference of -4.7 mmHg (95% CI -6.7 to -2.7). In patients with severe OSA, there was a maximum mean difference of -7.1 mmHg (95% CI -10.3 to -3.8).

The researchers concluded that good CPAP adherence can mitigate the long-term increase in blood pressure observed in ACS patients with severe OSA.

1. Sánchez De La Torre M, et al. Long-Term Effect of OSA and CPAP on Blood Pressure in Patients with Acute Coronary Syndrome: A Post-Hoc Analysis of the ISAACC Study. Session C19, ATS International Conference 2022, San Francisco, CA, USA, 13–18 May.
2. Sánchez-de-la-Torre M, et al. Ann Am Thorac Soc. 2022 Apr 20. Doi: 10.1513/AnnalsATS.202203-260OC.

 

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Posted on 18 July 202213 June 2024