BACKGROUND

Coronary heart disease (CHD) is the leading cause of mortality in the U.S. and worldwide.1,2 Cardiovascular health may in fact be worse for active duty servicemen when compared to the civilian population.3 Additionally, cardiovascular disease is the second most common chronic disease among active duty Army personnel following arthritis.4 While clinical CHD typically presents at older ages, significant coronary atherosclerosis and myocardial infarction can manifest in young adults and teenage patients.5 In a cross-sectional study by Webber et al, coronary atherosclerosis was identified in 8.5% of the autopsies performed on U.S. military personnel in Operation Iraqi Freedom/Operation New Dawn (OIF/OND) and Operation Enduring Freedom (OEF).6 In this study population, older age, lower educational level, higher body max index at military entrance, and a prior diagnoses of: dyslipidemia, hypertension, and obesity, were associated with a higher prevalence of atherosclerosis. Additionally, myocardial infarction (MI)/ACS was the most common medical/non-surgical diagnosis for Critical Care Air Transport Team (CCATT) evacuations, representing 6.6% of 290 patients evacuated by CCATT during OIF/OEF.7

Acute coronary syndrome is typically a consequence of CHD and refers to a spectrum of disease among patients experiencing, or suspected of experiencing, myocardial ischemia.8 ACS is further divided into three subgroups: 1) ST elevation myocardial infarction (STEMI), 2) non-ST elevation myocardial infarction (NSTEMI), and 3) unstable angina.

When evaluating patients with chest pain concerning ACS, it is important to consider other life-threatening causes of chest pain such as pulmonary emboli, pneumonia, aortic dissection, pneumothorax, esophageal rupture, and myocarditis as they are managed differently. A thorough history and physical exam may be helpful in guiding the deployed provider towards a presumptive diagnosis. When available, imaging, labs, and electrocardiogram (ECG) can further assist in differentiating the etiology of chest pain.9,10

Diagnosis and management of ACS can be uniquely challenging in locations where PCI centers or treatment with fibrinolytics are not available. PCI is recommended within 120 minutes of first medical contact and is the preferred and most common treatment for ACS in the U.S..11 However, if evacuation is required, the delay to reach a PCI center may exceed the recommended door-to-balloon time. Military physicians located Outside Continental United States (OCONUS) may therefore be required to treat ACS with fibrinolytics, which is not common in most U.S. locations. Additionally, many diagnostic tools helpful in evaluating chest pain, such as ECGs and cardiac troponin assays, may not be available in many deployed locations. Refer to Appendix C for ACS management recommendations by role of care.

It is the responsibility of every medical provider to be prepared for initial management of ACS, to include understanding how to use teleconference services. Diagnosis and treatment of ACS should be guided by expert consultation. In addition, the capability to obtain and transmit an ECG and to provide cardiac first aid treatments with oxygen, nitroglycerin and aspirin are key capabilities in initial stabilization and should be available to all deployed medical providers. Expanded capabilities for medical stabilization with anti-platelet agents, systemic anticoagulation and fibrinolytic therapy should be available in the evacuation chain within 24 hours, and must be considered during operational planning. Fibrinolytics are ideally given within 12 hours of symptom onset; however there may be a benefit up to 24 hours after symptom onset.12,13