The Universal Definition of MI
Editor's Note: Newer generations of troponin assays have increased sensitivity, allowing detection of small amounts of myocardial damage. Not infrequently, this increased sensitivity has led to diagnostic confusion, as at times it can be difficult to determine if the troponin increase is related to acute coronary syndrome, or a variety of other processes that can lead to acute/chronic myocardial damage.
The Cardiac Biomarkers editors asked experts in the field to comment on a case scenario that is not an infrequent occurrence for what their opinion was for the most appropriate diagnosis.
HPI: The patient is a 57-year-old male with a history of dyspnea on exertion that began two days prior to the admission. The episodes last 10-15 minutes and have been relieved with rest. On the day of admission, the patient complained of severe dyspnea at rest with associated diaphoresis and nausea. The symptoms began approximately two hours prior to the emergency department visit and are still present during the evaluation.
PMHx HTN treated with and ACEI, diuretic and amlodipine, for which he has been non-compliant for the past two weeks.
No prior coronary history or prior cardiac evaluation.
PE: BP 260/140 mm Hg. P 110 bpm.
Cardiac: tachycardic, + S4.
Lungs: rales ¼ up bilaterally.
Electrocardiogram (ECG): Sinus tachycardia with left ventricular hypertrophy (LVH) and 2 mm ST depression in V5 and V6 consistent with repolarization abnormalities or ischemia; no old ECG available for comparison.
cTnI: admission 0.05 ng/ml.
6 hours 0.14 ng/ml.
24 hours 0.07 ng/ml.
99th percentile for this assay is 0.03 ng/ml.
Repeat ECG the next day at a heart rate of 80 bpm shows 1mm ST (or could have no change still with 2 mm ST depression) depression in V5 and V6.
Coronary angiography is performed and shows non-obstructive coronary disease (mid LAD-50%, proximal Cx 60%, and RCA diffuse 30%).
Echocardiogram shows EF -70%, moderate left ventricular hypertrophy (LVH), and no focal wall motion abnormalities.
Is this an acute myocardial infarction (AMI) as defined by the universal definition of AMI 2012?