A 54-year-old woman is evaluated in the emergency department for jaw and shoulder pain that has occurred intermittently for the past week. The symptoms occur with activity and are relieved by rest. Medical and family history is unremarkable. She is not taking any medications.
Physical examination shows a blood pressure of 150/68 mm Hg and a pulse of 90/min. There is no jugular venous distention and carotid upstrokes are normal. There are no cardiac murmurs and the lung fields are clear. Extremities show no edema and peripheral pulses are normal bilaterally. The troponin I level is elevated.
Electrocardiogram shows 1.0-mm ST-segment depression in leads V1 through V4 with T-wave inversions.
The patient is given aspirin, intravenous nitroglycerin, low-molecular-weight heparin, clopidogrel, and atorvastatin.
The most appropriate additional treatment for this patient is metoprolol. This patient's elevated troponin I level and ST-segment depression and T-wave inversions on electrocardiogram are indicative of a non–ST-elevation myocardial infarction (NSTEMI). Early intravenous β-blocker therapy reduces infarct size, decreases the frequency of recurrent myocardial ischemia, and improves short- and long-term survival. β-Blockers diminish myocardial oxygen demand by reducing heart rate, systemic arterial pressure, and myocardial contractility; in addition, prolongation of diastole augments perfusion to the injured myocardium. β-Blocker therapy can be used in left ventricular dysfunction if heart failure status is stable.
An intra-aortic balloon pump is indicated for an acute coronary syndrome with cardiogenic shock that is unresponsive to medical therapy, acute mitral regurgitation secondary to papillary muscle dysfunction, ventricular septal rupture, or refractory angina. The intra-aortic balloon pump reduces afterload during ventricular systole and increases coronary perfusion during diastole. Patients with refractory cardiogenic shock who are treated with an intra-aortic balloon pump have a lower in-hospital mortality rate than patients who are not treated. This patient has no indication for an intra-aortic balloon pump.
Calcium channel blockers, such as verapamil, are also effective antianginal medications, but data are conflicting as to whether calcium channel blockers reduce mortality in patients with NSTEMI. Therefore, β-blockers are first-line therapy for unstable angina and NSTEMI unless contraindications are present. With ongoing ischemia despite β-blocker therapy, a calcium channel blocker can be added. However, there is no indication for starting verapamil rather than metoprolol at this time.
There is no role for the routine use of warfarin in the treatment of acute coronary syndrome, including NSTEMI. Warfarin is not associated with improved patient outcome as compared to treatment without warfarin. Warfarin may be considered in patients at increased risk for thromboembolism, such as those with atrial fibrillation.
- In patients with myocardial infarction, early intravenous β-blocker therapy reduces infarct size, decreases the frequency of recurrent myocardial ischemia, and improves short- and long-term survival.