COMPLICATIONS ASSOCIATED WITH MI

There are both early and late complications associated with MI. Early complications will be the focus here as these are the ones likely to be seen in the deployed setting during the initial hours to days of treatment.

Cardiogenic Shock

Cardiogenic shock is best defined as SBP < 90 mmHg for 30 minutes or SBP > 90 mmHg on vasopressors with evidence of end organ damage from a cardiovascular origin. The patient may have evidence of pulmonary edema (worsening dyspnea, crackles, worsening chest x-ray) or evidence of peripheral hypoperfusion (weak pulses, cold extremities). Listed below are the vasopressor/inotropic agents that should be utilized in this situation.39

1. Norepinephrine (preferred first line agent) - 5 – 20 mcg/min IV. Start at 5 mcg/min and increase by 2-5 mcg/min q15 minutes.
2. Dopamine - 0.5 to 20 mcg/kg/minute IV (lower doses preferred).

Mechanical Complications

Mechanical complications primarily manifest as either acute chordal rupture of the mitral valve, ventricular septal rupture, or left ventricular free wall rupture. These typically occur within the first 24 hours but can present within a week as well. The use of fibrinolytics is also a risk factor for an acute ventricular septal rupture and left ventricular free wall rupture. Medical therapy is only temporary with a high mortality rate for those unable to undergo surgical correction. Echocardiography is the modality of choice for rapid diagnosis. This can show pericardial effusion when associated with left ventricular free wall rupture.

Arrhythmias

There are multiple different tachy- and brady-dysrhythmias that can occur with acute MI. Most can be addressed using ACLS protocols. The most common rhythm following reperfusion is accelerated idioventricular rhythm (Figure 14). This manifests as a wide complex QRS rhythm (as you would see with ventricular tachycardia) with heart rates in the 50 – 110 bpm; it is benign and requires no intervention.40 Patients are typically asymptomatic with normal vital signs otherwise, and it should resolve spontaneously.