Unstable Angina
A 62-year-old man presents to the emergency department (ED) with complaints of pain in his chest and jaw. The pain, originally occurring only with exertion and resolving with rest, became increasingly persistent over the past 2 to 3 days. On the evening of his arrival, the patient experienced a 15-minute episode of severe pain while watching television. This episode he characterized as a •tight, burning feeling in my chest, and an aching in my jaw" that did not vary with respiratory effort and was accompanied by diaphoresis, nausea, and shortness of breath.
On arrival to the ED, his pain and nausea had resolved, pulse oximetry showed oxygen saturation of 98% on room air, and his vital signs were:
On physical examination, heart sounds were normal, without S3, S4, or murmurs. Initial diagnostic tests revealed:
• ECG: Normal sinus rhythm with nonspecific ST-T wave changes
• Chest x-ray: Normal cardiac silhouette, clear lungs
A more detailed assessment of his history revealed increasing dyspnca on exertion and fatigue for the previous 6 months. Despite these symptoms, he had continued his daily 2.5-mile walking routine, sometimes experiencing shortness of breath several times during the walk. The patient reported smoking cigarettes in the past, one pack per day for 20 years, but quit 25 years ago. No ankle swelling, nocturnal dyspnea, or orthopnea were reported, nor was he aware of any family history of cardiac problems, coronary artery disease, diabetes, or hypertension.
He was started on aspirin based on his history and the likelihood of underlying coronary artery disease. He was then admitted for observation and evaluation of cardiac enzymes (see section on cardiac enzymes).
Six hours after presenting to the ED, the patient had recurrent tightness in his chest. An ECG showed T-wave inversion in the anterior leads. Sublingual nitroglycerin 0.4 mg was administered every 5 minutes with complete relief of the pressure following the second tablet. An unfractionated heparin infusion was started. Subsequent cardiac enzymes showed:
Other laboratory results were normal with the exception of elevated cholesterol and triglycerides on the lipid panel. Following receipt of these results, he was scheduled for an exercise tolerance test.
The ECG recorded a heart rate of 118 beats/min after 6 minutes of exercise. Onset of chest tightness during the last minute of exercise was described as similar to that which brought him to the hospital and correlated with 1.5-mm ST depression in leads V4 to V6• A cardiac catheterization was scheduled.
Coronary angiography showed a 75% obstruction of the LAD artery and 90% obstruction of the diagonal branch of the same artery. LVEF was 55%. A coronary angioplasty (PTCA) was performed on both lesions.
What monitoring is the high.est priority during the patient's ED stay?
(A) Obtain repeat ECGs every 4 hours
(B) Continuous ECG/ST-segment monitoring for signs of.MI
(C) Monitor platelet levels every 6 hours
(D) Assess breath sounds every 2 hours
What diagnosis is suggested by the finding of ST-1egmcnt depn:11ion and T-waTI: invallion on the ECG?
(A) Non-ST-segment elevation MI
(B) ST-segment elevation MI
(C) Coronary spasm
(D) Pcricarditis
Following the PTCA, what critical complication i1 the patient at risk for?
(A) Increased heart rate of 115 beats/min
(B) Hypotension
(C) 4 mm ST-segment elevation in leads V3-V4
(D) All of the above