Usefulness of Q-Wave Area for Threshold-Based Stratification of Global Left Ventricular Myocardial Infarct Size

Abstract

Left ventricular (LV) infarct size affects prognosis after acute myocardial infarction (AMI). Delayed enhancement cardiac magnetic resonance (DE-CMR) provides accurate infarct quantification but is unavailable or contraindicated in many patients. This study tested whether simple electrocardiography (ECG) parameters can stratify LV infarct size. One hundred fifty-two patients with AMI underwent DE-CMR and serial 12-lead ECG. Electrocardiograms were quantitatively analyzed for multiple aspects of Q-wave morphology, including duration, amplitude, and geometric area (QWAr) summed across all leads except aVR. Patients with pathologic Q waves had larger infarcts measured by DE-CMR or enzymes (both p <0.001), even after controlling for infarct distribution by CMR or x-ray angiography. Comparison between early (4 ± 0.4 days after AMI) and follow-up (29 ± 6 days) ECG demonstrated temporal reductions in Q-wave amplitude (1.8 ± 1.4 vs 1.6 ± 1.6 mV; p = 0.03) but not QWAr (41 ± 38 vs 39 ± 43 mV•ms; p = 0.29). At both times, QWAr augmented stepwise with DE-CMR quantified infarct size (p <0.001). QWAr increased markedly at 10% LV infarct threshold, with differences more than threefold on early ECG (59 ± 39 vs 18 ± 20 mV•ms; p <0.001) and nearly fivefold (59 ± 46 vs 13 ± 16 mV•ms; p <0.001) on follow-up. Diagnostic performance compared with a 10% infarction cutoff was good on early (area under the curve = 0.84) and follow-up (area under the curve = 0.87) ECG. Optimization of sensitivity (95% to 98%) enabled QWAr to exclude affected patients with 90% to 94% negative predictive value at each time point. In conclusion, LV infarct size is accompanied by stepwise increments in Q-wave morphology, with QWAr increased three- to fivefold at a threshold of 10% LV infarction. Stratification based on QWAr provides excellent negative predictive value for exclusion of large (≥10%) LV infarct burden.

Q wave area for stratification of global left ventricular infarct size

“…This threshold-based approach is predicated on the well-established observation that Q waves (a central component of Selvester QRS-score) can be absent with small infarctions, 19, 20, 22 and plateau with large infarctions. 22 Such an approach is also consistent with recent clinical outcomes studies, which have shown both mortality and arrhythmic risk to be stratified based on binary cutoffs for infarct size. 16-18 …”

“…19-21 Our group has recently shown that Q wave area – a parameter that can be measured on routine 12-lead ECG – provides high negative predictive value for exclusion of large (≥10%) LV infarction. 22 Unlike Selvester QRS-score, which incorporates multiple ECG and clinical variables into a multi-parametric formula, Q wave area constitutes a single parameter for assessment of infarct burden, facilitating its application in routine clinical practice.…”

Morroniside on anti-inflammation activities in rats following acute myocardial infarction

“…Our data demonstrate that at 72 h following AMI, morroniside treatment resulted in a significant decline in Q(q) wave amplitude. Early post-AMI, total Q-wave amplitude (QWAmp) independently correlated with infarct size [ 13 ]. Large infarct size increased immediate morbidity and mortality and, in rats that survived this acute event, larger non-functional scars adversely affect long-term prognosis [ 14 ].…”

Echocardiography‐quantified myocardial strain—a marker of global and regional infarct size that stratifies likelihood of left ventricular thrombus

“…Demographic, clinical, and laboratory indices were collected at time of study enrollment, inclusive of CAD risk factors and MI treatment strategies. Electrocardiographic quantification of infarct size using Q‐wave area was performed in accordance with previously validated methodology . Initial patient recruitment and image acquisition were performed between September 2006 and September 2014 at Weill Cornell Medical College (New York, NY, USA).…”

“…Electrocardiographic quantification of infarct size using Q-wave area was performed in accordance with previously validated methodology. 16 Initial patient recruitment and image acquisition were performed between September 2006 and September 2014 at Weill Cornell Medical College (New York, NY, USA). For this study, available primary digital echo images were retrieved from data archives and reanalyzed (blinded to CMR and demographic indices) for the specific purpose of testing incremental utility of myocardial strain as a marker of infarct size and thrombus.…”