Discordance of diagnosis of ventricular aneurysm made by the electrocardiogram and myocardial imaging: "ST-segment counterpoise" as a hypothetical mechanism.

There is a discordance between ECG and imaging modalities in the diagnosis of ventricular aneurysm (VA) consequent to an old myocardial infarction. A hypothesis is being proposed that this discordance, which results in electrocardiograms (ECGs) not showing ST-segment elevations (+ST) in patients with proven by imaging modalities to have VA (false negative, low diagnostic sensitivity), may be due to "ST-segment counterpoise," rendering the ECG isoelectric. Accordingly, +ST generated by myocardial territories involved with the VA, when poised opposite each other, cancel out via vectorial summation, rendering the ECG falsely negative for VA. Also, a misalignment of the apex longitudinal axis with the left ventricular inflow axis due to myocardial remodeling from the VA (boot-shaped heart) when the apex and another myocardial region are involved with VA leads to +ST cancellation and a false-negative ECG for VA. ST-segment counterpoise as a mechanism rendering the ECG falsely negative for VA can be tested in the future if studies of patients with VA adopt in their methodologies a systematic reporting of severity and topography [corrected] of the regional left ventricular contraction abnormalities, as recommended by the American Society of Echocardiography.