ECG Pattern Interpretation for Cardiac Pathology

Primary Diagnostic Considerations

The American College of Cardiology recommends that T-wave abnormalities ≥1 mm in depth in two or more contiguous leads in lateral territories require further assessment, as they are not recognized features of normal cardiac physiology 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, with a strength of evidence based on clinical guidelines from the American College of Cardiology 1
If initial echocardiography is non-diagnostic, cardiac MRI with gadolinium should be utilized to assess for myocardial hypertrophy and late gadolinium enhancement suggesting myocardial fibrosis, as recommended by the American College of Cardiology 1
The American Heart Association, as reported in Circulation, notes that critical technical consideration: Superior misplacement of V1 and V2 electrodes can cause reduction of initial R-wave amplitude, creating artifactual poor R-wave progression or erroneous signs of anterior infarction 2
Proper electrode placement must be verified before attributing poor R wave progression to pathology, according to the American Heart Association, as reported in Circulation 2

The American College of Cardiology states that before attributing sinus tachycardia to primary cardiac pathology, comprehensive evaluation for secondary causes is mandatory, including pyrexia, hypovolemia, anemia, infections, hyperthyroidism, and medications 3
Pathological causes to evaluate include pyrexia, hypovolemia, anemia, infections, hyperthyroidism, and medications, as outlined by the American College of Cardiology 3

The American College of Cardiology recommends verifying proper ECG electrode placement to exclude technical artifact causing poor R wave progression, and obtaining cardiac biomarkers to assess for acute myocardial injury 2
The American College of Cardiology suggests reviewing medication list and vital signs to identify secondary causes of sinus tachycardia 3
Comprehensive echocardiography should be performed to evaluate left ventricular wall thickness and function, as recommended by the American College of Cardiology 1
If echocardiography is non-diagnostic or shows "grey zone" findings, cardiac MRI with gadolinium should be utilized to assess for cardiomyopathy, myocardial fibrosis, or subtle infarction, according to the American College of Cardiology 1

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, as recommended by the American College of Cardiology 1
Ventricular tachycardia during exercise or Holter monitoring may support diagnosis of hypertrophic cardiomyopathy and aids in risk stratification, according to the American College of Cardiology 1

Superior misplacement of V1–V2 (2nd or 3rd intercostal space) reduces the initial R‑wave amplitude by ≈0.1 mV for each interspace, creating artifactual poor R‑wave progression that can mimic anterior infarction. – American College of Cardiology (JACC) & American Heart Association (Circulation) 4
When V1–V2 are placed too high, an rSr′ pattern with T‑wave inversion frequently appears, resembling the morphology of lead aVR. – American College of Cardiology (JACC) & American Heart Association (Circulation) 4
In patients with a low diaphragmatic position (e.g., chronic obstructive pulmonary disease), recording V3–V4 above the ventricular borders can simulate anterior myocardial infarction on the ECG. – American College of Cardiology (JACC) & American Heart Association (Circulation) 5

Presence of pathologic Q waves in leads V1–V3 (duration ≥ 0.02 s or QS complex) is a specific ECG marker for anterior myocardial infarction. – American College of Cardiology (JACC) 6
Concomitant ST‑segment and T‑wave abnormalities in the anterior leads further support the diagnosis of anterior myocardial infarction. – American College of Cardiology (JACC) 6

Echocardiography is recommended for all patients with poor R‑wave progression (unless a normal variant is confidently identified) to evaluate wall‑motion abnormalities, left‑ or right‑ventricular hypertrophy, or cardiomyopathy. – American College of Cardiology (JACC) 6

All bullet points are derived from peer‑reviewed sources; the strength of evidence was not explicitly stated in the cited publications.