Sigmoid-Shaped (Biphasic) T-Waves in V2-V3: Wellens' Syndrome Type A
A sigmoid-shaped or biphasic T-wave pattern in leads V2-V3 without frank inversion represents Wellens' syndrome Type A, a critical ECG finding that indicates severe proximal left anterior descending (LAD) coronary artery stenosis and impending anterior myocardial infarction requiring urgent coronary angiography.
What This Pattern Means
This specific T-wave morphology—rising and falling like a curve rather than being inverted—is the Type A variant of Wellens' syndrome 1, 2. The biphasic configuration (initial positive deflection followed by negative deflection, or vice versa) in the anterior precordial leads V2-V3 is a pre-infarction pattern that typically appears during a pain-free period after recent chest pain episodes 3, 4.
Key Clinical Context
The pattern you're describing occurs in patients with:
- Recent history of chest pain or crescendo angina (often within the past few days)
- Currently asymptomatic or pain-free when the ECG is obtained
- Normal or minimally elevated cardiac biomarkers (troponins may be normal or only slightly elevated) 1, 3
- Critical stenosis (typically 95-99%) of the proximal LAD artery 3, 4
Why This Matters Urgently
This ECG pattern identifies patients at extremely high risk (up to 75%) of developing extensive anterior wall myocardial infarction within days to weeks if not treated with revascularization 5. The guidelines explicitly state that marked symmetrical precordial T-wave changes strongly suggest acute ischemia, particularly due to critical LAD stenosis 6, 7.
The deeply inverted T-wave pattern with QT prolongation in leads V2-V4 should be interpreted as consistent with severe stenosis of the proximal LAD 5. Your biphasic pattern is the precursor or variant of this finding.
Immediate Management Algorithm
- Do NOT perform stress testing - This can precipitate extensive anterior MI 1
- Urgent cardiology consultation for coronary angiography
- Medical therapy: Aspirin, antiplatelet agents (clopidogrel, ticagrelor, or prasugrel), anticoagulation 8
- Admit for monitoring and expedited catheterization
- Expect percutaneous coronary intervention (PCI) with stent placement as definitive treatment 1, 3
Two Types of Wellens' Syndrome
- Type A (25% of cases): Biphasic T-waves in V2-V3 (what you're describing) 1, 2
- Type B (75% of cases): Deep, symmetric T-wave inversions (≥2mm) in V2-V4 1, 2
Important clinical pearl: Type A can evolve into Type B after the acute ischemic episode resolves or after reperfusion 9, 3. One case report documented Type A pattern converting to Type B after stent placement, representing reperfusion changes 3.
Diagnostic Accuracy
Biphasic or negative T-waves in V2-V3 have 76% sensitivity for identifying proximal LAD stenosis in acute coronary syndrome patients, compared to only 11% in patients without LAD involvement 4. This makes it a highly reliable marker that outperforms troponin levels and clinical risk scores for identifying this specific high-risk anatomy 4.
Critical Pitfall to Avoid
The most dangerous error is dismissing this pattern as "nonspecific ST-T changes" because:
- Cardiac biomarkers may be normal or only minimally elevated 1, 3
- The patient is often pain-free when the ECG is obtained 3
- The pattern may be subtle compared to obvious ST-elevation MI
The guidelines classify nonspecific ST-T changes as ST deviation <0.5mm or T-wave changes <2mm 6, 7, but biphasic T-waves in the anterior leads should never be considered nonspecific when there's a history of recent chest pain.