Out Inferior Infarct: Cannot Rule

The interpretive algorithm of a modern ECG machine is a statistical device. When it outputs “cannot rule out inferior infarct,” it is essentially stating: “The probability of pathological Q waves or ST-segment deviations in leads II, III, and aVF is above a threshold of concern, but below the threshold of certainty.”

Add right-sided leads V3R and V4R. ST elevation of ≥0.5 mm in V4R has a sensitivity of 90% and specificity of 95% for acute right ventricular infarction—a finding that changes management (avoid nitrates, maintain preload). cannot rule out inferior infarct

To understand the phrase, we have to break down the anatomy. The interpretive algorithm of a modern ECG machine