What does a flattened T wave in V6, low T wave in V5, and poor R wave progression in V2 with sinus tachycardia indicate?

ECG Pattern Interpretation: Flattened T Wave in V6, Low T Wave in V5, Poor R Wave Progression in V2 with Sinus Tachycardia

This ECG pattern suggests possible underlying cardiac pathology requiring urgent evaluation, most concerning for left anterior descending coronary artery disease (including Wellens' syndrome), cardiomyopathy, or anterior myocardial injury, though technical factors and secondary causes of sinus tachycardia must first be excluded.

Primary Diagnostic Considerations

T-Wave Abnormalities in Lateral Leads (V5-V6)

Flattened or low T waves in V5-V6 are abnormal findings that mandate comprehensive cardiac evaluation to exclude structural heart disease, particularly cardiomyopathy. 1

• T-wave abnormalities ≥1 mm in depth in two or more contiguous leads in lateral territories are not recognized features of normal cardiac physiology and always require further assessment 1
• Lateral T-wave abnormalities (affecting V5-V6, I, and aVL) are associated with quiescent cardiomyopathy in a considerable proportion of patients and should prompt comprehensive investigation including echocardiography 1
• If initial echocardiography is non-diagnostic, cardiac MRI with gadolinium should be utilized to assess for myocardial hypertrophy (especially left ventricular apex and lateral free wall) and late gadolinium enhancement suggesting myocardial fibrosis 1

Poor R Wave Progression in V2

Poor R wave progression has four distinct major causes that must be systematically evaluated: anterior myocardial infarction, left ventricular hypertrophy, right ventricular hypertrophy, and normal variant with diminished anterior forces. 2

• Standard ECG criteria can identify and distinguish these causes, making systematic evaluation essential 2
• Critical technical consideration: Superior misplacement of V1 and V2 electrodes (in the second or third intercostal space instead of the fourth) can cause reduction of initial R-wave amplitude approximating 0.1 mV per interspace, creating artifactual poor R-wave progression or erroneous signs of anterior infarction 1
• Proper electrode placement must be verified before attributing poor R wave progression to pathology 1

Combined Pattern: Wellens' Syndrome Consideration

The combination of T-wave abnormalities in precordial leads with poor R wave progression warrants urgent evaluation for critical LAD stenosis, particularly Wellens' syndrome. 3

• Wellens' syndrome consists of symmetrically inverted or biphasic T waves in precordial leads (frequently V2-V3) associated with critical LAD stenosis and impending myocardial infarction 3
• T-wave pseudonormalization can occur, where initially abnormal T waves appear normal on subsequent ECGs despite ongoing critical coronary disease 3
• This pattern requires urgent coronary angiography as it indicates high risk for acute myocardial infarction 3

Sinus Tachycardia Evaluation

Secondary Causes Must Be Excluded First

Before attributing sinus tachycardia to primary cardiac pathology, comprehensive evaluation for secondary causes is mandatory. 1

Pathological causes to evaluate include:

• Pyrexia, hypovolemia, anemia, infections 1
• Pulmonary embolism 4
• Hyperthyroidism 1, 4
• Medications: stimulants (caffeine, nicotine), prescribed compounds (salbutamol, aminophylline, atropine, catecholamines), recreational drugs (amphetamines, cocaine) 1
• Anthracycline chemotherapy (doxorubicin, daunorubicin) causing acute cardiotoxic response 1

Inappropriate Sinus Tachycardia

If secondary causes are excluded, consider inappropriate sinus tachycardia (IST):

• Defined as persistent elevation in resting heart rate (>100 bpm at rest or >90 bpm average over 24 hours) unrelated to physiological stress, accompanied by symptoms 5
• Predominantly affects females (approximately 90%), mean age 38 years, with high proportion being healthcare professionals 1
• Mechanisms include enhanced sinus node automaticity and abnormal autonomic regulation with excess sympathetic and reduced parasympathetic tone 1

Diagnostic Algorithm

Immediate Steps

1. Verify proper ECG electrode placement to exclude technical artifact causing poor R wave progression 1
2. Obtain cardiac biomarkers (troponin T, B-type natriuretic peptides) to assess for acute myocardial injury 3
3. Review medication list and vital signs to identify secondary causes of sinus tachycardia 1

Urgent Cardiac Evaluation

Given the combination of lateral T-wave abnormalities and poor R wave progression, proceed with:

1. Comprehensive echocardiography to evaluate:

   • Left ventricular wall thickness and function 1
   • Regional wall motion abnormalities suggesting ischemia or infarction 2
   • Right ventricular size and function 2

2. If echocardiography is non-diagnostic or shows "grey zone" findings:

   • Cardiac MRI with gadolinium to assess for cardiomyopathy, myocardial fibrosis, or subtle infarction 1
   • Exercise ECG testing and Holter monitoring, especially for patients with borderline hypertrophy (males with maximal LV wall thickness 13-16 mm) 1

3. If acute coronary syndrome is suspected (particularly Wellens' pattern):

   • Urgent coronary angiography is indicated 3
   • Intravascular ultrasonography may confirm plaque rupture with thrombosis 3

Follow-Up Considerations

• Serial cardiac imaging is necessary even when initial evaluation is normal, to monitor for development of cardiomyopathy phenotype in patients with lateral T-wave abnormalities 1
• Ventricular tachycardia during exercise or Holter monitoring may support diagnosis of hypertrophic cardiomyopathy and aids in risk stratification 1

Common Pitfalls to Avoid

• Do not dismiss T-wave flattening in V5-V6 as benign without comprehensive structural evaluation, as this pattern is associated with cardiomyopathy 1
• Do not attribute poor R wave progression to anterior infarction without first verifying proper electrode placement, as superior misplacement of V1-V2 is a common technical error 1
• Do not overlook Wellens' syndrome when T-wave abnormalities are present in precordial leads, as this represents critical LAD disease requiring urgent intervention 3
• Do not diagnose inappropriate sinus tachycardia until all secondary causes have been thoroughly excluded and treated 5