Table 1

Definition and classification of ECG findings: the BIRNH study

	Minnesota codes
Major ECG findings	IV_1–2 or V_1–2 or VI_1–2 or VII_1–2 or VIII_1–3
Minor ECG findings	I₃ or II_1–2 or III_1–2 or IV₃ or V₃ or IX₁
Only minor ECG findings	Minor ECG changes but no major ECG changes
Ischaemic ECG findings	I₃ or IV_1–3 or V_1–3 or VII₁
ST depression	IV_1–3
Abnormal T wave	V_1–3
Arrhythmias	VIII_1–6 or VI_1–2,4
Bundle branch blocks	VII_1-2,4
Left ventricular hypertrophy	III₁ and (IV_1–3 or V_1–3)
Left axis deviation	II₁