Can the 12-Lead Electrocardiogram Predict Myocardial Viability?

Abstract

Introduction: In patients with coronary artery disease and left ventricular dysfunction, the assessment of myocardial viability, prior to revascularisation has been shown to be of significant benefit. Most methods to assess myocardial viability such as Positron Emission Tomography (PET) and Cardiac MRI (CMR) are not readily available in resource constrained settings. The present study sought to determine if an easily available and inexpensive tool, such as the 12-lead surface Electrocardiogram (ECG) can be used as a screening tool to assess for myocardial viability. It is hypothesised that the R wave height as a marker of electrical activity would correlate with viability. Aim: To determine if the surface ECG can be used to predict myocardial viability. Materials and Methods: This retrospective study was conducted at the Christian Medical College and Hospital, Vellore, Tamil Nadu, India. Among all patients who had undergone CMR viability assessment as part of their routine care between February 2008 and October 2017, and analysis and preliminary write up was done between November 2017 and Decemeber 2018, 119 patients with previous anterior wall myocardial infarctions were identified. The 12-Lead ECGs of these patients were assessed for the height of R wave in lead V3 and sum of R wave heights in all precordial leads. Myocardial viability was assessed based on the extent of Late Gadolinium Enhancement (LGE) on CMR. Measures of diagnostic accuracy including sensitivity, specificity, predictive values and likelihood ratios were calculated. Results: It was found that a R wave height of less than 3 mm in lead V3 was 90.3% sensitive for the detection of non viable myocardium. Similarly, when the sum of the R wave heights in all precordial leads was less than 28.5 mm, it was 93.2% sensitive for the detection of non viable myocardium. Conclusion: In patients with previous anterior wall myocardial infarctions when the R wave height was less than 3 mm in lead V3, it was 90.3 % sensitive to identify those with non viable Left Anterior Descending artery (LAD) territory. The 12-Lead ECG is therefore a sensitive, inexpensive and easily available screening test to assess for LAD territory non viability.