Broken Hearts

Story:

Patient is a 64 year-old male with a history of hypertension and hyperlipidemia presenting with 3 hours of chest pain. He received 325 mg of aspirin and 2 nitroglycerine tablets en route with EMS with moderate improvement. His EKG is below:

On this initial EKG, the following are visualized:

This EKG demonstrates sinus rhythm with a prolonged PR interval (normal PR intervals are 0.12-0.2 milliseconds). The QRS complexes are narrow, with Q waves present in leads V1-V2. There are Q waves present in leads V1-V2. The T waves are large in comparison to the QRS. A normal T wave should be approximately half the size of the QRS. In this patient the T waves, especially in the anterior leads, are twice the size of the QRS. The ST segments in both V1 and V2 are elevated, to 1.5mm and 2mm respectively. Although there is beat-to-beat variability, There may be depressions in leads II, V5, and V6.

Discussion:

Is this an ischemic EKG? There are several signs here that the patient is having an ischemic cardiac event:

Q waves: If not involved in a conduction abnormality (such as partial or complete bundle branch block) or strain pattern, Q waves generally indicate that a patient has had or is having ischemia within a geographic distribution. Q waves can develop as early as 1-2 hours after the onset of symptoms although sometimes take 12-24 hours to appear. Unlike other EKG signs of ischemia, Q waves are persistent changes that mark old ischemia and subsequent scar tissue. Q waves reliably predict areas of previous infarct or scar tissue 100% of the time.

ST segments: The ST segments are elevated in leads V1 and V2. By AHA guidelines, ST segment elevation threshold for ST-elevation myocardial infarction are as follows:

Men > 40 years: 2mm in leads V2, V3. 1mm in all others.

Men < 40 years: 2.5mm in leads V2, V3. 1mm in all others.

Women: 1.5mm in leads V2, V3. 1mm in all others.

Using these criteria for ST elevation myocardial infarction, the patient meets threshold criteria in lead V1 and is borderline in V2. The upsloping morphology of the ST segment in lead V2 is reassuring, as ischemic ST segments tend to be more planar or convex. The differential for sub-millimeter ST segment elevation includes acute myocardial ischemia as well as pericarditis, benign early repolarization, left ventricular aneurysm, bundle branch block, and vasospasm.

T waves: In a normal EKG, T waves should be no larger than approximately 1/2 the QRS segment. In this patient, the T waves are nearly double in lead V2. Hyperacute T waves caused by ischemia usually present for only 5 to 30 minutes after the onset of the infarction and then resolve. The differential for hyperacute T waves includes hyperkalemia, which is more likely to cause diffuse T waves.

Story, continued:

This EKG was read as normal, likely benign early repolarization accounting for the ST elevation in the anterior leads. The patient's initial troponin was 0.04 and he was started on heparin for a presumed non ST-elevation MI. His subsequent troponin 2 hours later was 40. The EKG at that time is as shown:

As you can see here, the patient has had progression of his Q waves with deep Q waves present in leads V1-V3. The apparent hyperacute T waves noted previously have resolved, and the patient continues to have ST elevations of approximately 2 mm in both leads V2 and V3. The patient was taken emergently to the cath lab where he was found to have a 95% occlusion of the very proximal LAD.

Upon chart review, the patient's EKG taken en route was found buried within other documentation and showed the following strip:

Visible here are several signs of ischemia, including Q waves in leads V1-V3, hyperacute T waves in leads V2-V5, and impressive and obvious reciprocal depressions with T wave inversions in leads III and aVF. Taken in combination with the presenting EKG, these EKGs are highly concerning for evolving ischemia and active early infarct.

Discussion:

1. If the chest pain has resolved or improved, an EKG from the time of greatest pain can be diagnostic.

2. If the T waves is greater than half the QRS, it is hyperacute and indicative of ischemia or hyperkalemia.

3. Hyperacute T waves require rapid, serial EKGs.

References:

Birnbaum Y, et al. Common pitfalls in the interpretation of electrocardiograms from patients with acute coronary syndromes with narrow QRS: a consensus reportJ Electrocardiol, 45 (2012), pp. 463–475

Brady WJ, Morris F. Acute Myocardial Infarction, Part 1. BMJ. 2002 Apr 6; 324(7341): 831–834.

Hollander JE, Diercks DB. Acute Coronary Syndromes: Acute Myocardial Infarction and Unstable Angina.

Levis JT. ECG Diagnosis: Hyperacute T Waves. Perm J. 2015 Summer; 19(3): 79.