What are the differential diagnoses for a 60-year-old female with chest pain, elevated troponin levels, and an electrocardiogram (ECG) showing sinus rhythm (SR) with runs of ventricular tachycardia (VTach)?

Three Strong Differential Diagnoses

In a 60-year-old female with chest pain, elevated troponin, and runs of ventricular tachycardia, the three most critical differentials are: (1) Acute myocardial infarction with electrical instability, (2) Acute myocarditis, and (3) Takotsubo (stress-induced) cardiomyopathy. 1

1. Acute Myocardial Infarction (Type 1 MI)

This is the most immediately life-threatening diagnosis that must be excluded first. 1

• The combination of chest pain, elevated troponin, and ventricular arrhythmias represents high-risk acute coronary syndrome requiring urgent coronary angiography 1
• Elevated troponin with ventricular tachycardia runs strongly suggests acute myocardial injury with electrical instability 1
• In a 60-year-old female, the likelihood of coronary artery disease causing angina is approximately 90% 2
• ST-segment changes on ECG (even if currently in sinus rhythm) and the pattern of troponin rise (rapid substantial increases over hours) would support this diagnosis 2

Key distinguishing features:

• Serial troponin measurements at 3-6 hour intervals showing a rising/falling pattern indicate acute MI 1
• Regional wall motion abnormalities on echocardiography that correspond to a specific coronary artery territory 3
• Subendocardial or transmural delayed contrast enhancement on cardiac MRI if performed 3

2. Acute Myocarditis

This can present identically to acute MI with chest pain, troponin elevation, ECG changes, and ventricular arrhythmias. 2

• Myocarditis patients may present with symptoms similar to acute myocardial infarction, including angina pectoris, ST-segment elevations on ECG, and elevated troponin 2
• Supraventricular and ventricular tachyarrhythmias are common in myocarditis patients 2
• In one study of 80 patients with suspected ACS and normal coronary arteries, 63% had acute myocarditis as the final diagnosis 3

Key distinguishing features:

• Normal or non-obstructive coronary arteries on angiography 3
• Subepicardial and middle segment delayed contrast enhancement on cardiac MRI (not subendocardial) 3
• Wall motion abnormalities extending beyond a single coronary territory 2
• May have preceding viral prodrome or recent infection 2

3. Takotsubo (Stress-Induced) Cardiomyopathy

This diagnosis is particularly relevant in a 60-year-old female, as it predominantly affects postmenopausal women. 4

• Acute myocardial infarction itself can trigger stress-induced cardiomyopathy, creating a mixed picture 4
• Presents with chest pain, ECG changes (often anterior ST elevation), and troponin elevation 4, 5
• Ventricular arrhythmias can occur due to marked QTc prolongation 4

Key distinguishing features:

• Wall motion abnormalities extending beyond the distribution of a single coronary artery territory 4
• Characteristic apical ballooning with relative sparing of basal segments on echocardiography 4, 3
• Modest troponin elevation (typically ≤ moderate) despite extensive wall motion abnormalities 4
• Marked QTc prolongation on ECG 4
• Absence of delayed contrast enhancement on cardiac MRI 3
• Rapid improvement in left ventricular function on early repeat echocardiography 4
• Single culprit lesion (if any) that doesn't explain the extent of dysfunction 4

Critical Next Steps

Immediate coronary angiography is mandatory to exclude obstructive coronary disease. 1

• Urgent echocardiography must be performed to assess for mechanical complications (specifically mitral regurgitation from papillary muscle dysfunction or rupture), ventricular function, and regional wall motion patterns 1
• Continuous cardiac monitoring for recurrent ventricular arrhythmias is necessary 2, 1
• Serial troponin measurements at 3-6 hour intervals are essential to detect rising/falling patterns 1

Important caveats:

• Pulmonary embolism and aortic dissection can also cause troponin elevation and must be considered, though less likely with runs of VTach 1
• The differential diagnosis narrows with higher troponin values and the pattern of rise 2
• If coronary angiography shows normal arteries, cardiac MRI becomes the gold standard for distinguishing between myocarditis and Takotsubo cardiomyopathy 2, 3