What is the clinical significance of a biphasic T wave on an electrocardiogram (ECG) in a patient presenting with hypotension and without any significant past medical history?

Biphasic T Wave on ECG: Clinical Significance and Management

What a Biphasic T Wave Represents

A biphasic T wave on ECG—particularly in the precordial leads V2-V3—is a critical warning sign of impending myocardial infarction due to severe stenosis of the proximal left anterior descending (LAD) coronary artery, known as Wellens' syndrome, and requires urgent cardiac evaluation and revascularization to prevent extensive anterior wall infarction. 1, 2, 3

Critical Context: Hypotension Without Prior Cardiac History

In a patient presenting with hypotension and biphasic T waves, this represents an extremely high-risk scenario requiring immediate intervention:

• Marked symmetrical precordial T-wave inversion or biphasic T waves (≥2 mm) strongly suggest acute ischemia from critical LAD stenosis, with patients often exhibiting anterior wall hypokinesis and being at high risk with medical management alone 1, 4
• The combination of biphasic T waves with hemodynamic instability (hypotension) places the patient at the highest risk tier for acute coronary syndrome, warranting immediate cardiology consultation and consideration for emergent coronary angiography 1
• These patients are at imminent risk of massive anterior myocardial infarction or sudden cardiac death if not promptly revascularized 2, 5

Wellens' Syndrome: The Classic Biphasic T Wave Pattern

Two Distinct ECG Patterns

Wellens' syndrome presents with two characteristic patterns, both indicating the same critical pathology:

• Type A (Biphasic T waves): Biphasic T waves with initial positivity followed by terminal negativity, seen in approximately 25% of cases 2, 3
• Type B (Deep T-wave inversion): Deeply and symmetrically inverted T waves, seen in approximately 75% of cases 2, 3
• Both patterns most commonly appear in leads V2-V3, though they may extend to V1-V4 or beyond 1, 4, 2

Diagnostic Criteria and Recognition

The key features that distinguish Wellens' syndrome include:

• Biphasic or deeply inverted T waves in precordial leads V2-V3 (or extending to V1-V4) during a pain-free period 2, 3, 5
• Preserved R wave progression (distinguishing it from prior infarction) 3
• Minimal or no ST-segment elevation (<1 mm) 2, 3
• Normal or minimally elevated cardiac biomarkers initially 3, 5
• Recent history of chest pain that has typically resolved at the time of ECG 2, 3, 5

Location-Specific Biphasic T Wave Patterns

Inferior Lead Biphasic T Waves

• Biphasic T waves or T-wave inversions in inferior leads (II, III, aVF) indicate critical stenosis of the right coronary artery (RCA) or left circumflex artery (LCx), representing an "inferior Wellens sign" 6
• This pattern may precede inferior-posterior STEMI and requires the same urgent approach as anterior Wellens' syndrome 6
• T-wave inversion in inferior and/or lateral leads must raise suspicion of ischemic heart disease, cardiomyopathy, aortic valve disease, systemic hypertension, and LV non-compaction 4, 7

Combined Patterns

• The presence of both inferior T-wave inversions and tall T waves in V2-V3 may indicate impending inferior-posterior STEMI, representing combined "inferior and posterior Wellens signs" 6

Immediate Management Algorithm for Biphasic T Waves with Hypotension

Within First 10 Minutes

1. Obtain 12-lead ECG immediately and compare with any prior tracings to identify new changes 4, 7
2. Check vital signs, establish IV access, and administer aspirin 162-325 mg (unless contraindicated) 4
3. Obtain initial cardiac biomarkers (troponin, CK-MB) 4, 3
4. Administer sublingual nitroglycerin for ongoing chest discomfort (avoid if hypotensive with SBP <90 mmHg) 4
5. Initiate continuous cardiac monitoring for arrhythmia detection 4

Urgent Diagnostic Workup (Within Hours)

• Serial troponin measurements at 0,1-2, and 3 hours to assess for dynamic changes, even though initial troponins may be normal or minimally elevated in Wellens' syndrome 4, 3
• Urgent cardiology consultation for consideration of emergent coronary angiography 4, 2, 3
• Echocardiography to assess for regional wall motion abnormalities (anterior wall hypokinesis suggests LAD involvement) 4, 3

Critical Management Decision

Do NOT perform stress testing in patients with suspected Wellens' syndrome, as exercise can precipitate massive anterior wall myocardial infarction 2, 3, 5

Definitive Treatment

• Emergent coronary angiography is the gold standard to identify the critical LAD stenosis 2, 3, 5
• Percutaneous coronary intervention (PCI) with stenting is the treatment of choice to prevent impending myocardial infarction 2, 3, 5
• Early invasive revascularization therapy prevents massive myocardial infarction or sudden death 5

Alternative Diagnoses for Biphasic T Waves

While Wellens' syndrome is the most critical diagnosis to exclude, biphasic T waves can occasionally represent:

Cardiac Causes

• Acute pericarditis: Distinguished by diffuse ST elevation, PR depression, and pleuritic chest pain; however, biphasic T waves developing after initial presentation may indicate evolving ischemia rather than pericarditis 8
• Myocarditis: May present with T-wave changes and elevated troponin, but typically has more diffuse ECG changes and preserved coronary arteries on angiography 4
• Cardiomyopathy: T-wave inversions may be the initial phenotypic expression before structural changes appear on imaging 4, 7

Non-Cardiac Causes

• Pulmonary embolism: Can produce T-wave inversions in right precordial leads with right-sided strain pattern 1, 7
• Central nervous system events (intracranial hemorrhage): Can cause deep T-wave inversions with QT prolongation 4, 7
• Medications: Tricyclic antidepressants and phenothiazines can cause deep T-wave changes 7

Prognostic Significance and Risk Stratification

• Patients with ACS and T-wave inversion are at lower risk for death compared to those with ST-segment elevation, but higher risk than those with normal ECGs 7
• However, Wellens' syndrome specifically carries extremely high risk (up to 75% risk of extensive anterior wall MI within weeks if not revascularized) 2, 3, 5
• The presence of hypotension with biphasic T waves indicates hemodynamic compromise and places the patient in the highest risk category requiring immediate intervention 1, 4

Critical Pitfalls to Avoid

• Never dismiss biphasic T waves as "nonspecific" without proper evaluation, especially in the context of recent chest pain or hemodynamic instability 4, 6, 2
• Do not confuse Wellens' syndrome with pericarditis; the evolution of ECG changes and clinical context are key differentiators 8
• Avoid stress testing in suspected Wellens' syndrome, as this can precipitate the very myocardial infarction you are trying to prevent 2, 3, 5
• Do not be falsely reassured by normal or minimally elevated initial troponins; Wellens' syndrome often presents during a pain-free period with minimal biomarker elevation 3, 5
• Recognize that T-wave "pseudonormalization" (return to upright T waves) may occur and represents a dangerous sign of ongoing ischemia, not improvement 3

Special Consideration: T-Wave Pseudonormalization

• If previously documented biphasic or inverted T waves suddenly normalize, this may represent "pseudonormalization" during active ischemia and is a dangerous sign requiring immediate intervention 3
• Serial ECGs are essential to detect this dynamic change 3