11
Chapter 2
MYOCARDIAL INFARCTION, ACUTE CORONARY
SYNDROMES, AND CPR.
Recommendations are considered Category 1B by the WMS Panel of Expert Reviewers.
I. GENERAL INFORMATION:
Acute Coronary Syndrome (ACS), including myocardial infarction and unstable angina
is a major cause of mortality. Chest pain is the most common reason for emergency calls
to the US Coast Guard and is the most common reason for EMS dispatch in the US. In
Urban areas, approximately 15% of EMS transports for chest pain are due to documented
ACS; in more rural areas, such as Scandinavia, up to 30% of chest pain victims arriving
to hospital by EMS transport have ACS. In the U.S., mortality from ACS rises
proportionally with the distance a victim lives from a CCU. In the pre-defibrillator era,
mortality from myocardial infarction was 50%. In the years after defibrillators were
available, but before thrombolytics were routinely used, acute mortality from ACS was
approximately 15-20%, and was improved mainly due to the routine use of aspirin,
betablockers and nitrates. In the post-thrombolytic era, mortality fell to 5-10%. With
advent of angioplasty for ACS, acute mortality in tertiary referral hospitals in the United
States approaches 3-5% and in Europe remains 5-7%. It is now recognized that arterial
pathology with platelet rich thrombii and inflammed, ulcerative plaque is the same in
unstable angina as in myocardial infarction, only the extent of coronary flow obstruction
is different. Immediate evacuation saves lives in the setting of ACS. The quickest route to
the hospital is the best route, even if the victim has to walk at a slow pace. Physical rest is
preferred, but if litter transport is impossible due to terrain or lack of assistance, the
victim should attempt slow self rescue. Reperfusion therapy, even up to 36 hrs post
infarction, will reduce long term mortality and complications from infarction. Death
occurs from arrhythmias (bradycardic or tachycardic), shock (with or without pulmonary
edema) or stroke. Even in settings far from medical help, simple measures can reduce
mortality while evacuation is proceeding.
Recognition of Acute coronary syndromes:
·
Symptoms: Chest Pain with or without radiation to the arm or Jaw.
Unstable angina pain will wax and wane and may be relieved by
nitroglycerin. Pain radiating to the back or stomach suggests
inferior MI. Myocardial Infarction pain will not be completely
relieved by nitrates.
Nausea with both anterior and Inferior MI. When associated with
diarrhea is usually a sign of impending shock with Inferior MI and
represents vagal shock.
