Description of the Change in a Novel Cardiac Electric Biomarker during Acute Ischemia induced by Percutaneous Coronary Intervention

Background
VectraplexECG (VectraCor Inc, Totowa, New Jersey) is a novel, FDA-approved 15 lead electrocardiographic instrument. The system uses a patented, proprietary algorithm to derive what is termed a cardiac electric biomarker (CEB). The company reports that by looking at the multi-polarity of the electrical field, they can produce the CEB that is a reliable predictor of the presence of myocardial infarction. We postulated that among patients with stable obstructive coronary artery disease undergoing percutaneous coronary intervention (PCI) for treatment of angina pectoris, we would see a brief, dynamic change in the CEB resulting from the transient ischemia that occurs during balloon inflations

Methods
100 patients were selected that were undergoing elective PCI for stable angina or stable acute coronary syndrome. VectraplexECG monitoring electrodes were placed on these patients to obtain a baseline CEB. CEB data was obtained before, during, and after balloon inflation for stent implantation and then every 30 seconds after balloon deflation until the CEB returned to baseline. A linear mixed model was used to test for differences between mean CEB values at 30 and 60 seconds compared to baseline. A single categorical variable was included for the three time points and a subject specific random effect was used to account for repeated measures.

Results
Mean CEB at baseline was 165.35. Mean CEB was 142.54 (22.81 units lower than baseline, p-value 0.486) and 146.06 (19.29 units lower than baseline, p-value 0.664) at 30 and 60 seconds respectively. It was found that there was no statistically significant difference in the CEB values at 30 and 60 seconds compared to baseline. After standardizing the subject’s baseline CEB values and building control limits for the baseline, we noted that 44% of patients had a shift in their CEB values

Conclusions
Promising novel markers of coronary ischemia are needed and may have an important role in the early and accurate diagnosis of ischemia. However, we did not find a statistically significant rise and fall relationship between the CEB and induced coronary ischemia. Potential limitations of this study include an inadequate duration of ischemia or the presence of collateral flow limiting the burden of ischemia.