A Catecholamine Conundrum
A 49-year-old man presented to the emergency department with a 3-day history of chest pain, flu-like symptoms, and palpitations. His medical history was significant for hypertension, dyslipidemia, diabetes mellitus, and anxiety. On initial examination, he was hypertensive with a blood pressure of 209/137 mmHg and tachycardic with a heart rate of 112 bpm. He was extremely anxious and diaphoretic. The rest of the physical exam was unremarkable. His presenting electrocardiogram (ECG) showed ST-segment elevation in the inferior and antero-lateral leads (Figure 1), consistent with an ST-segment elevation myocardial infarction. Aspirin, clopidogrel, and intravenous unfractionated heparin were administered, and he underwent urgent cardiac catheterization.
Figure 1: Presenting ECG Showing ST-Segment Elevation
Coronary angiography demonstrated only a 40% stenosis in the first obtuse marginal branch with no other evidence of obstructive coronary artery disease (CAD). However, left ventriculography showed apical dyskinesis with normal basal contractility (Video 1). He was transferred to the cardiac intensive care unit for further investigation and management. High-sensitivity Troponin I level from bloodwork drawn on presentation was 3716 ng/L (reference ≤45ng/L), and creatine kinase was 352 U/L (reference 30-250 U/L). Screening for cocaine and amphetamines was negative. A transthoracic echocardiogram (TTE) (Video 2) showed moderate-to-severe left ventricular (LV) dysfunction (LV ejection fraction of 25-35%) and confirmed apical akinesis and normal basal contractility.
Video 1: Left Ventriculogram Showing Normal Basal Contractility and Apical Dyskinesis
Video 2: TTE on Day of Presentation Showing Apical Dyskinesis and Moderately-to-Severely Reduced LV Systolic Function
The next day, he was found to be in circulatory shock (initially presumed cardiogenic) with hypotension; tachycardia; cool, clammy extremities; and decreased urinary output. He was profoundly diaphoretic, drenching the entire bed with sweat. Bloodwork showed an elevated lactate. A pulmonary artery catheter was inserted and showed low central venous pressure (2 mmHg) and low pulmonary capillary wedge pressure (5 mmHg), which was more consistent with hypovolemic shock. He was aggressively fluid resuscitated and quickly recovered clinically and hemodynamically. He was later started on medical therapy for heart failure, including a beta-blocker and an angiotensin-converting enzyme inhibitor.
Cardiac magnetic resonance imaging (MRI) 48 hours later showed that LV function had almost normalized. There was no evidence of late gadolinium enhancement, regional wall motion abnormalities, myocardial edema, or valvular pathology. He was discharged home in stable condition. A repeat echocardiogram 1 week following discharge showed normalized LV function with improved wall motion abnormalities (Video 3).
Video 3: TTE Following Discharge With Normalized LV Systolic Function and Improved Wall Motion Abnormalities
Unfortunately, he presented 2 weeks later with chest pain and was again hypertensive with blood pressure of 190/130 mmHg, tachycardic with a heart rate of 130 bpm, diaphoretic, and extremely anxious. A repeat ECG (which had normalized prior to discharge) demonstrated ischemic changes with deep T-wave inversions in the anterior leads (Figure 2). A repeat echocardiogram showed recurrence of apical akinesis with severe LV dysfunction in a pattern similar to that previously seen. He was admitted to the cardiac intensive care unit; early in his hospital course, he experienced extremely labile blood pressure and paroxysms of tachycardia, diaphoresis, extreme anxiety, and headaches.
Figure 2: ECG on Repeat Presentation
Based on the patient's presentation and angiographic, echocardiographic, and MRI findings, what is the most likely diagnosis?