Patients with sleep apnea have less severe cardiac injury during an acute non-fatal Myocardial Infarction (MI) compared to patients without sleep apnea, according to a Montefiore Medical Center study, entitled "Obstructive Sleep Apnea and Acute Myocardial Infarction Severity: Ischemic Preconditioning," to be published in Sleep and Breathing on Oct. 24.

"Our results appear to be contrary to existing literature that identifies obstructive sleep apnea (OSA) to be a risk factor for Myocardial Infarction," said Neomi Shah, MD, MPH, Pulmonary Sleep Lab, Associate Director, Montefiore Medical Center, and Assistant Professor of Medicine, Albert Einstein College of Medicine of Yeshiva University, and principal investigator of the study. "While our data do not refute a widely accepted view that sleep apnea is a risk factor for the development of a coronary artery disease related event such as a Myocardial Infarction, our study suggests that obstructive sleep apnea can provide a degree of cardioprotection during the acute phase of a Myocardial Infarction."

The study that screened over 6,000 hospitalized patients on the cardiology units at Montefiore found that this degree of cardioproetection can reduce the severity of the heart attack. A number of factors led to this conclusion. First, acute MI patients with severe sleep apnea tended to have a lower median level of peak Troponin-T compared to those without OSA. Troponin-T is a marker in the blood for myocardial cell death and it accurately predicts the severity of a heart attack. In addition, patients with OSA had lower levels of creatine phosphokinase (CPK) as compared with non-OSA patients. CPK is an enzyme found in the blood and when it is high, it usually indicates that there has been an injury or stress to muscle mass. These novel findings suggest that OSA may be cardioprotective in the acute phase of a MI.

The final number of patients in the analytical sample of this study was 136, based on the number who agreed to participate and who had adequate sleep data. Of this group, 35% had obstructive sleep apnea. Their median age was 58 years and 47% were men. These patients also exhibited a high prevalence of hypertension (77%), hyperlipidemia (56%) and diabetes (50%). Patients with OSA were significantly older than those without OSA (age 62 vs. 52).

The study was conducted from April, 2010 to May, 2011.

Dr. Shah, who has been Associate Director of the Pulmonary Sleep Lab at Montefiore Medical Center since 2008, has focused her research interests on understanding the relationship between OSA and coronary artery disease. She received her medical degree from Robert Wood Johnson Medical School and completed her residency in internal medicine at the University of Medicine & Dentistry in Newark, NJ. She completed her fellowship in pulmonary, critical care and sleep medicine at Yale University School of Medicine.

In addition to Dr. Shah, the research team included Susan Redline, MD, MPH, H. Klar Yaggi, MD, MPH, Richard Wu, MD, C. George Zhao, MD, Robert Ostfeld, MD, Mark Menegus, MD, Daniel Tracy, Elizabeth Brush, BA, W. David Appel, MD, and Robert Kaplan, PhD.