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. 2019 Jan;24(1):e12601.
doi: 10.1111/anec.12601. Epub 2018 Sep 28.

Ischemic QRS prolongation as a biomarker of myocardial injury in STEMI patients

Jakob Almer  1 , Viktor Elmberg  2 , Josef Bränsvik  1 , David Nordlund  1 , Ardavan Khoshnood  3 , Michael Ringborn  4 , Marcus Carlsson  1 , Ulf Ekelund  3 , Henrik Engblom  1
Affiliations

Ischemic QRS prolongation as a biomarker of myocardial injury in STEMI patients

Jakob Almer et al. Ann Noninvasive Electrocardiol. 2019 Jan.

Abstract

Background: Patients with acute coronary occlusion (ACO) may not only have ischemia-related ST-segment changes but also changes in the QRS complex. It has recently been shown in dogs that a greater ischemic QRS prolongation (IQP) during ACO is related to lower collateral flow. This suggests that greater IQP could indicate more severe ischemia and thereby more rapid infarct development. Therefore, the purpose was to evaluate the relationship between IQP and measures of myocardial injury in patients presenting with acute ST-elevation myocardial infarction (STEMI).

Methods: Seventy-seven patients with first-time STEMI were retrospectively included from the recently published SOCCER trial. All patients underwent a cardiac magnetic resonance (CMR) examination 2-6 days after the acute event. Infarct size (IS), myocardium at risk (MaR), and myocardial salvage index (MSI) were assessed and related to IQP. IQP measures assessed were; computer-generated QRS duration, QRS duration at maximum ST deviation, absolute IQP and relative IQP, all derived from a pre-PCI, 12-lead ECG.

Results: Median absolute IQP was 10 ms (range 0-115 ms). There were no statistically significant correlations between measures of IQP and any of the CMR measures of myocardial injury (absolute IQP vs IS, r = 0.03, p = 0.80; MaR, r = -0.01, p = 0.89; MSI, r = -0.05, p = 0.68).

Conclusions: Unlike previous experimental studies, the IQP was limited in patients presenting at the emergency room with first-time STEMI and no correlation was found between IQP and CMR variables of myocardial injury in these patients. Therefore, IQP does not seem to be a suitable biomarker for triaging patients in this clinical context.

Keywords: QRS; acute coronary occlusion; electrocardiography; ischemia.

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Figures

Figure 1
Figure 1
Depiction of ischemic QRS prolongation measurement method. During ischemia, when no J‐point could be clearly distinguished due to ST‐elevation a line was drawn through the peak of the R (or R’ if it was present) wave and along 40% of the downslope between the R peak and the nadir of the ST segment. Reprinted from Almer et al. (2016), copyright (2016), with permission from Elsevier
Figure 2
Figure 2
Co‐localized mid‐ventricular left ventricular slices showing myocardium at risk, infarction and myocardial salvage in a patient after myocardial injury caused by occlusion‐reperfusion of the right coronary artery. Green lines delineate epicardium, red lines endocardium, white line myocardium at risk, and orange line infarction. In the image to the right, the infarct delineation has been superimposed upon the myocardium at risk delineation where salvaged myocardium is indicated in white
Figure 3
Figure 3
Electrocardiography examples from a patient with a LAD occlusion (a) and a patient with an RCA occlusion (b). (a) Twelve‐lead ECG with maximum ST‐deviation in lead V2 (1) of 0.525 mV. Since there is a distinguished J‐point, it is used as offset, resulting in a QRS duration at maximum ST deviation of 90 ms. Lead V6 (2) was used as a reference, showing a QRS duration of 85 ms, resulting in an absolute ischemic QRS prolongation of 5 ms. (b) Twelve‐lead ECG with maximum ST‐deviation in lead III (3) of 0.425 mV. Since no clear j point can be determined, the intersect method for QRS duration was applied, resulting in a QRS duration at maximum ST deviation of 150 ms. Lead I (4) was used as a reference, showing a QRS duration of 82 ms, resulting in an absolute ischemic QRS prolongation of 65 ms
See this image and copyright information in PMC

References

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