In the latest Case Record of the Massachusetts General Hospital, a 52-year-old man was brought to the emergency department with chest pain and ST-segment elevation. Seconds after his arrival, cardiac arrest occurred. CPR was begun, and nine external countershocks were administered, without resolution. Management decisions were made.
The 2013 STEMI guidelines indicate that primary percutaneous coronary intervention (PCI), provided it can be performed promptly (within 90 minutes after first contact with the health care system for most patients), is the preferred strategy. Intravenous thrombolysis remains a viable option but is used to a much lesser degree in this country.
•What are the indications for immediate cardiovascular revascularization therapy?
Indications for revascularization therapy include a history of chest pain typical of ischemia within 12 hours of continuous symptom onset, along with ST elevations of 1 mm or more in two contiguous leads or a left bundle-branch block not known to be old or electrocardiography (ECG) evidence of an isolated posterior-wall infarction.
•What adjunctive treatments are useful in the emergency department for a patient with a STEMI while waiting for the cardiac catherization team?
Several adjunctive treatments in the emergency department while waiting for the catheterization team to be ready are indicated, but none should delay the transfer of the patient. All patients should receive aspirin, generally 325 mg chewed and swallowed. Further antiplatelet therapy, with ticagrelor, prasugrel, or clopidogrel can also be administered in the emergency department. Anticoagulation therapy with either unfractionated heparin or low-molecular-weight heparin can be initiated. A glycoprotein IIb-IIIa inhibitor may be administered but this decision is best deferred to the catheterization lab. Intravenous beta blockers may be considered in the emergency department but should be withheld both from patients with bradycardia, heart block, or signs of heart failure, and from patients with heart rate >100 or age >75. Nitrates may be administered to patients with STEMI, but since they provide no mortality advantage, should generally be deferred in patients with suspected concomitant right ventricular infarction, aortic stenosis, recent phosphodiesterase inhibitor use, or hypotension.
Morning Report Questions
Q: What is the role for hypothermia in improving neurologic outcomes in patients who are comatose after cardiac arrest and return of spontaneous circulation (ROSC)?
A: Hypothermia has been shown to improve neurological outcomes in patients who are comatose after cardiac arrest and ROSC. In two large, randomized trials, patients cooled to 32 to 34 degreesC within 2 to 8 hours after ROSC and maintained at that temperature for 12 to 24 hours were more likely to have good recovery or mild-to-moderate disability than controls (relative risk, 1.4 to 1.9). A smaller study showed some benefit from a shorter hypothermia course (4 hours) in patients who had asystole or pulseless electrical activity cardiac arrest. A Cochrane review confirmed that patients who are comatose after cardiac arrest who undergo therapeutic hypothermia are more likely to have a good neurologic outcome (relative risk, 1.55; 95% CI, 1.22 to 1.96) compared with standard care.
Q: What is the role for extracorporeal membrane oxygenation (ECMO) in the setting of cardiogenic shock associated with an STEMI?
A: There is evidence that early venoarterial extracorporeal membrane oxygenation (VA-ECMO) improves survival in patients with cardiogenic shock after STEMI. Patient selection is important in determining who will benefit from ECMO support during fulminant cardiogenic shock in the setting of an STEMI. Chances of survival are higher in younger patients, in those without chronic illnesses, and those that receive successful primary PCI. In some cases, ECMO may be started in the cardiac catheterization lab prior to PCI. The reasoning is threefold: full cardiac support is attained immediately, allowing perfusion of the vital organs and limiting the risk of multisystem organ failure; cerebral cooling through the ECMO circuit is initiated earlier; and it is technically easier to perform PCI with ECMO support rather than during ongoing CPR.