Performance of ST and ventricular gradient difference vectors in electrocardiographic detection of acute myocardial ischemia

- Detection of acute ischemia in triage ECGs of patients with chest pain is of utmost importance but remains problematic because of the limited diagnostic performance.
- Comparison of an acute ECG with a previously electively made non-ischemic ECG of the same patient can possibly increase diagnostic performance; especially changes in the ST amplitude (ΔST) and in the ventricular gradient (ΔVG) are useful for the detection of acute ischemia.
- In this study, we serially analyzed sets of two ECGs electively made in 398 patients with cardiovascular disease but without acute ischemia (controls) and sets of two ECGs made in 84 patients just before and during elective balloon occlusions of a coronary artery (cases).
- Receiver operating characteristic analysis of ΔST and ΔVG revealed an improved ischemia detection performance of ΔST compared with conventional STEMI diagnosis.

IntroductionSerial analysis could improve ECG diagnosis of myocardial ischemia caused by acute coronary occlusion.MethodsWe analyzed ECG pairs of 84 cases and 398 controls. In case-patients, who underwent elective percutaneous coronary intervention, ischemic ECGs during balloon occlusion were compared with preceding non-ischemic ECGs. In control-patients, two elective non-ischemic ECGs were compared. In each ECG the ST vector at the J point and the ventricular gradient (VG) vector was computed, after which difference vectors ΔST and ΔVG were computed within patients. Finally, receiver operating characteristic analysis was done.ResultsAreas under the curve were 0.906 (P < 0.001; CI 0.862-0.949; SE 0.022) for ΔST and 0.880 (P < 0.001; CI 0.833-0.926; SE 0.024) for ΔVG. Sensitivity and specificity of conventional ST-elevation myocardial infarction (STEMI) criteria were 70.2% and 89.1%, respectively. At matched serial analysis specificity and STEMI specificity, serial analysis sensitivity was 78.6% for ΔST and 71.4% for ΔVG (not significantly different from STEMI sensitivity). At matched serial analysis sensitivity and STEMI sensitivity, serial analysis specificity was 96.5% for ΔST and 89.3% for ΔVG; ΔST and STEMI specificities differed significantly (P < 0.001).ConclusionDetection of acute myocardial ischemia by serial ECG analysis of ST and VG vectors has equal or even superior performance than the STEMI criteria. This concept should be further evaluated in triage ECGs of patients suspected from having acute myocardial ischemia.