Table 2.

Criteria for major and minor ECG abnormalities sensu the Minnesota code classification system.

Criterion	Minnesota code
Major ECG abnormalities
Cicatricial changes in the myocardium	1–1, 1–2
Possible cicatricial changes in the myocardium	1–3 with 4–1, 4–2, 5–1, 5–2
Isolated pronounced ST-T wave changes	4–1, 4–2, 5–1, 5–2 without 1–1, 1–2, 1–3, 3–1, 3–3, 3–2, 3–4
Left ventricular hypertrophy with pronounced ST-T wave changes	3–1 with 4–1, 4–2, 5–1, 5–2
Major rhythm and conduction abnormalities	6–1, 6–2, 6–8, 6–4-1, 6–4–2, 7–1, 7–2, 7–4, 7–8, 7–9, 8–3
Significantly prolonged ventricular repolarization	QTI > 116%
Other severe arrhythmias	8–2–1, 8–2–2, 8–4–2, (8–4–1 provided HR ≥ 140 bpm)
Minor ECG abnormalities
Possible cicatricial changes in the myocardium	1–3 without 4–1, 4–2, 5–1, 5–2
Minor isolated ST segment and T wave changes	4–3, 4–4, 5–3, 5–4
Amplitude signs of ventricular myocardial hypertrophy	3–1, 3–2, 3–3, 3–4 without 4–1, 4–2, 5–1, 5–2
Minor conduction disorders	6–5, 6–3, 7–3, 7–6, 7–7
Minor arrhythmias	8–1–1, 8–1–2, 8–1–3, 8–1–5, 8–1–4, 8–7, 8–8, (8–4–1 provided HR < 140 bpm)
Slightly prolonged ventricular repolarization	112% ≤ QTI < 116%
Other minor ECG abnormalities	7–10, 9–1, 9–3, 9–6, 9–7

HR heart rate, QTI QT interval index, calculated as: QTI (%) = (QT/656) × (HR + 100); at QRS ≥ 120, JTI is calculated instead of QTI: JTI (%) = (JT/518) × (HR + 100), where JT = QT – QRS, and all intervals are in milliseconds (msec); bpm beats per minute.