Terminal QRS Distortion as a Variable to Identify Occlusion Myocardial Infarction

Robert Nicholson, MD, H. Pendell Meyers, MD, Alexander Bracey, MD, Daniel Lee, MD, Andrew Lichtenheld, MD, Wei J. Li, MD, Daniel D. Singer, MD, Jesse A. Kane, MD, Kenneth W. Dodd, MD, Kristen E. Meyers, MENG, Henry C. Thode, PHD, Gautam R. Shroff, MD, MBBS, FACC, Adam J. Singer, MD, and Stephen W. Smith, MD

Background: ST-segment elevation (STE) has been utilized as the primary surrogate finding of acute coronary occlusion on electrocardiogram (ECG), creating the “STEMI vs. NSTEMI” paradigm. Yet, 25-30% of NSTEMI patients have occlusion myocardial infarction (OMI) found on delayed angiogram and have increased mortality compared to the NSTEMI patients without OMI. It has been proposed that a more nuanced understanding of ECG interpretation rather than screening with STEMI criteria alone may improve diagnosis of OMI. One such feature is terminal QRS distortion (TQRSD). This is the first study evaluating the diagnostic accuracy of TQRSD for the diagnosis of OMI.

Methods: Secondary analysis of the retrospective case-control study from the Diagnosis of Occlusion MI and Reperfusion by Interpretation of the Electrocardiogram in Acute Thrombotic Occlusion Database (DOMI ARIGATO) database. Chart review was performed by Emergency Medicine physicians and data collected included demographics, clinical and laboratory results, ECGs, and angiographic findings using the web-based Research and Electronic Data Capture (REDCap). ECG interpretation was performed blinded to all patient information except age and sex. The diagnosis of OMI was adjudicated by structured chart review. Diagnostic accuracy of any lead (except aVR) with TQRSD for the outcome of OMI was reported. McNemar’s test of paired proportions was used for comparison of sensitivity and specificity between TQRSD and STEMI criteria.

Results: Among 808 ED patients presenting with ACS symptoms, 265 (33%) met the outcome definition of OMI. One hundred eighty-six (23%) were identified as having at least one lead with TQRSD. TQRSD had a sensitivity of 53% (95% CI 47-59%) and specificity of 92% (95% CI 89-94%) for the diagnosis of OMI. Using McNemar’s test for paired proportions to compare TQRSD and STEMI criteria, specificity was statistically similar (92% vs. 94%, p=0.081), but sensitivity was significantly greater for TQRSD (54% vs. 41%, p<0.001).

Conclusions: TQRSD had greater sensitivity than STEMI criteria for diagnosis of OMI and maintained high specificity. TQRSD may help identify OMI patients who do not meet traditional STEMI criteria.