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. 2015 May 3;12(5):378-86.
doi: 10.7150/ijms.11224. eCollection 2015.

Reduction of QTD--A Novel Marker of Successful Reperfusion in NSTEMI. Pathophysiologic Insights by CMR

Christoph J Jensen  1 , Sarah Lusebrink  1 , Alexander Wolf  1 , Thomas Schlosser  2 , Kai Nassenstein  2 , Christoph K Naber  1 , Georg V Sabin  1 , Oliver Bruder  1
Affiliations

Reduction of QTD--A Novel Marker of Successful Reperfusion in NSTEMI. Pathophysiologic Insights by CMR

Christoph J Jensen et al. Int J Med Sci. .

Abstract

Background/objectives: Non-ST segment elevation myocardial infarction (MI) poses similar detrimental long-term prognosis as ST-segment elevation MI. No marker on ECG is established to predict successful reperfusion in NSTEMI. QT dispersion is increased by myocardial ischemia and reduced by successful restoration of epicardial blood flow by PCI. Whether QT dispersion reduction translates to smaller infarcts and thus indicates successful reperfusion is unknown. We hypothesized that the relative reduction of QT dispersion (QTD-Rrel ) on a standard ECG in acutely reperfused NSTEMI is related to infarct size and infarct transmurality as assessed by delayed enhancement CMR (DE-CMR).

Methods and results: 69 patients with a first acute NSTEMI were included. QTD-Rrel was stratified according to LV function and volumes, infarct transmurality and size as assessed by DE-CMR. Extensive myocardial infarction was defined as above median infarct size. LV function and end-systolic volume were only mildly related to QTD-Rrel . QTD-Rrel was inversely related to infarct size (r=-0.506,p=0.001) and infarct transmurality (r=-0.415, p=0.001). QTD-Rrel was associated with extensive myocardial infarction in univariate analysis (odds ratio (OR) 0.958, CI 0.935-0.982; p=0.001). Compared to clinical and angiographic data QTD-Rrel remained the only independent predictor of non-transmural infarcts (OR 1.110, CI 1.055-1.167; p=0.049).

Conclusion: In patients with acute Non-ST-Segment Myocardial infarction QTd-Rrel calculated on a surface ECG prior and post PCI for restoration of epicardial blood flow detects small, non-transmural infarcts as assessed by delayed enhancement CMR. Thus, QTd-Rrel can indicate successful reperfusion therapy.

Keywords: QT dispersion; acute myocardial infarction; cardiac magnetic resonance imaging.; non-ST-elevation myocardial infarction.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interest exists.

Figures

Figure 1
Figure 1
Methods figure how we calculated mean infarct transmurality. The infarct sector was defined by the infarct lateral border (red line) in every slice and the area of infarct sector was summed up on a per heart basis. The area of delayed enhancement (above 5SD compared to remote myocardium) was traced and summed up for every slice. The average infarct transmurality was calculated as the ratio of the area of delayed enhancement to the area of the infarct sector and expressed as percentage.
Figure 2
Figure 2
Left ventricular volumes and function (a-c) and delayed enhancement findings (d-f) are stratified according to tertiles of QTd-Rrel from prior to post revascularization in patients with acute NSTEMI. A) Left ventricular ejection fraction (%) increased, b) end-systolic volume (ml) decreased significantly between first and third QTd-Rrel tertile. The number of infarcted segments (d), as well as the transmurality (f) and the size of infarcts (e) decreased from first to third QTd-Rrel tertile (p=0.001).
Figure 3
Figure 3
A) CMR scan of an 63-year-old male exhibiting only a minor reduction of QTd-Rrel post revascularization (QTd-Rrel 1st tertile). This patient had extensive, predominantly transmural myocardial infarction (average infarct transmurality: 95%, QTd-Rrel :0%) with presence of microvascular obstruction. B) A typical CMR scan of a patient with high reduction QTd-Rrel . This 60-year-old male was categorized to the 3rd tertile of QTd-Rrel . CMR images showed limited, non-transmural infarction (average infarct transmurality: 22%, QTd-Rrel: 80%).
Figure 3
Figure 3
A) CMR scan of an 63-year-old male exhibiting only a minor reduction of QTd-Rrel post revascularization (QTd-Rrel 1st tertile). This patient had extensive, predominantly transmural myocardial infarction (average infarct transmurality: 95%, QTd-Rrel :0%) with presence of microvascular obstruction. B) A typical CMR scan of a patient with high reduction QTd-Rrel . This 60-year-old male was categorized to the 3rd tertile of QTd-Rrel . CMR images showed limited, non-transmural infarction (average infarct transmurality: 22%, QTd-Rrel: 80%).
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