Ischemic Pre-Conditioning is Present in Patients with Non-ST Elevation Myocardial Infarction and ECG Derived Moderate...

Area of Science:

• Cardiology
• Sleep Medicine
• Internal Medicine

Background:

• Obstructive Sleep Apnea (OSA) is linked to increased cardiovascular event risk, including Acute Coronary Syndrome (ACS).
• Conflicting evidence exists regarding OSA's potential cardioprotective role in ACS patients, possibly through ischemic pre-conditioning.
• This study investigates the relationship between OSA and cardiac injury markers in ACS.

Purpose of the Study:

• To compare peak troponin levels between non-ST elevation ACS (NSTE-ACS) patients with and without moderate OSA.
• To identify moderate OSA using a Holter-derived respiratory disturbance index (HDRDI).
• To determine the frequency of transient myocardial ischemia (TMI) in NSTE-ACS patients with and without moderate HDRDI.

Main Methods:

• Secondary analysis of 110 NSTE-ACS patients using 12-lead ECG Holter recordings.
• Moderate OSA defined as HDRDI ≥15 events/hour, identified via QRSs, R-R intervals, and myogram.
• TMI defined as ≥1 mm ST-segment deviation in ≥1 lead for ≥1 minute.

Main Results:

• 39% of NSTE-ACS patients (n=43) had moderate HDRDI.
• Patients with moderate HDRDI exhibited higher peak troponin levels (10.2 ng/ml) compared to those without (6.8 ng/ml; p=0.037).
• A trend towards fewer TMI events was observed in moderate HDRDI patients (16% vs 30%; p=0.081), but this was not statistically significant.

Conclusions:

• NSTE-ACS patients with moderate OSA (moderate HDRDI) showed less cardiac injury, measured by peak troponin, than those without.
• Findings support prior research suggesting a potential cardioprotective effect of OSA in ACS via ischemic pre-conditioning.
• Further research is needed to elucidate the physiological mechanisms behind these observations, especially regarding TMI trends.