Should assessment be pursued in patients with chronic ST elevation that has increased in size?

Assessment of Chronic ST Elevation with Increased Size

Yes, urgent assessment should be pursued in patients with chronic ST elevation that has increased in size, as dynamic ST-segment changes—even in the setting of baseline abnormalities—may indicate acute coronary occlusion or evolving myocardial infarction requiring immediate intervention. 1

Rationale for Urgent Evaluation

The key principle is that dynamic ECG changes supersede baseline abnormalities. While chronic ST elevation can occur in conditions like left ventricular aneurysm, pericarditis, or early repolarization, an increase in the magnitude of ST elevation represents a change from baseline that warrants immediate investigation. 1

Critical Diagnostic Approach

Serial ECG monitoring is essential when ST elevation increases:

• Obtain serial ECGs at 5-10 minute intervals to document the evolution of ST-segment changes 1
• Compare current ECG with prior recordings whenever possible to quantify the degree of change 1
• Continuous 12-lead ST-segment monitoring should be performed if available to detect ongoing dynamic changes 1

Immediate clinical assessment must include:

• Presence or absence of ischemic symptoms (chest pain, dyspnea, diaphoresis) 2
• Hemodynamic stability and signs of heart failure or cardiogenic shock 1
• Focused neurological examination if fibrinolytic therapy is being considered 1

When to Activate Emergency Protocols

Activate STEMI protocols if:

• The patient has symptoms consistent with acute myocardial ischemia AND increased ST elevation 1
• There is suspicion of ongoing coronary occlusion even without diagnostic ST elevation, as some acute occlusions (circumflex territory, left main disease) may present atypically 1
• The clinical context suggests acute coronary syndrome despite chronic baseline ST changes 1

Consider immediate coronary angiography when:

• ST elevation has increased in magnitude with ongoing ischemic symptoms, regardless of baseline ECG abnormalities 1
• There is clinical suspicion of acute MI that cannot be definitively excluded by ECG alone 1
• Echocardiography shows new regional wall motion abnormalities suggesting acute ischemia 1

Diagnostic Adjuncts

Do not delay reperfusion decisions for biomarkers:

• Cardiac troponins should be obtained but reperfusion therapy must not be delayed waiting for results 1, 2
• Serial biomarker measurements cannot reliably diagnose reinfarction within the first 18 hours after STEMI onset 1, 2

Bedside echocardiography is valuable:

• Can identify new wall motion abnormalities suggesting acute ischemia 1
• Particularly useful when ECG interpretation is confounded by baseline abnormalities 1
• Should not delay definitive angiography if clinical suspicion remains high 1

Common Pitfalls to Avoid

Do not dismiss increased ST elevation as "chronic changes" without thorough evaluation—dynamic ECG changes in any patient with ischemic symptoms should trigger urgent assessment, even if baseline ST elevation exists. 1

Do not rely solely on biomarkers to make reperfusion decisions—the ECG and clinical presentation should drive immediate management, with biomarkers providing supportive information. 1, 2

Do not assume all ST elevation patterns are STEMI equivalents—certain patterns like multilead ST depression with ST elevation in aVR represent severe ischemia but not acute coronary occlusion requiring emergent reperfusion, and should be managed as NSTE-ACS. 3

Recognize non-ischemic mimics such as hypothermia, which can cause diffuse ST elevation with J waves that resolve with rewarming, but maintain a low threshold for angiography when doubt exists. 4, 5

Algorithmic Decision Framework

1. Document the change: Obtain serial ECGs and compare with prior tracings 1
2. Assess symptoms: Presence of ischemic symptoms elevates urgency dramatically 2
3. Evaluate hemodynamics: Unstable patients require immediate intervention 1
4. Consider bedside echo: If ECG interpretation is uncertain 1
5. When in doubt, proceed to angiography: Suspicion of ongoing ischemia is an indication for invasive evaluation even without diagnostic ST elevation 1

The overarching principle is that increased ST elevation in a patient with chronic baseline changes represents a dynamic process until proven otherwise, and the risk of missing acute MI far outweighs the risk of unnecessary catheterization. 1