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[Myocardial viability in QS region after PTCR]
Insights
Thallium-201 uptake in myocardial infarction regions is a better indicator of heart muscle viability than ECG's QS waves. This finding is crucial for assessing recovery after percutaneous transluminal coronary recanalization (PTCR).
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Percutaneous transluminal coronary recanalization (PTCR) is a key intervention for acute myocardial infarction.
- Assessing myocardial viability post-PTCR is crucial for predicting patient outcomes.
- Electrocardiogram (ECG) QS waves are traditionally associated with transmural infarction, but their accuracy in viability assessment is debated.
Purpose of the Study:
- To evaluate myocardial viability using Thallium-201 (Tl-201) SPECT imaging one month after PTCR in patients with first anterior myocardial infarction.
- To compare the diagnostic utility of Tl-201 uptake with ECG findings in determining myocardial viability.
- To investigate the relationship between left ventricular ejection fraction (EF) and myocardial viability.
Main Methods:
- Coronal myocardial SPECT imaging with Tl-201 profile curves was performed one month post-PTCR.
- Patients were stratified into two groups based on left ventricular ejection fraction (EF): Group A (EF > 50%) and Group B (EF < 50%).
- Serum GOT levels, %Tl-201 uptake in the quincke region (QS), infarct size, and ECG abnormalities were analyzed.
Main Results:
- Patients with higher EF (Group A) showed significantly greater %Tl-201 uptake in the infarct region compared to those with lower EF (Group B).
- Despite abnormal QS waves on ECG in both groups, %Tl-201 uptake greater than 50% in the QS region did not consistently indicate transmural necrosis.
- Improvement in regional wall motion was observed in 9 patients in Group A and 2 patients in Group B.
Conclusions:
- %Tl-201 uptake in the infarct region is a more reliable indicator of myocardial viability than ECG QS waves after PTCR.
- Myocardial salvage, contributing to ejection fraction in the chronic phase, may occur even with initial signs of necrosis and ECG abnormalities.
- Tl-201 SPECT imaging provides valuable insights into myocardial viability, aiding in the assessment of recovery and guiding treatment strategies post-myocardial infarction.
Abstract:
Myocardial viability after PTCR in patients with first anterior myocardial infarction was studied one month after the onset of acute myocardial infarction by profile curve of Tl-201 coronal myocardial SPECT images. Patients were devided into two groups according to left ventricular ejection fraction (EF), i.e. group A (EF more than 50%; 11 cases , EF; 62 +/- 10%) and group B (EF less than 50%; 9 cases, EF; 40 7%). Patients in group A showed an increase in serum GOT at the acute phase of acute myocardial infarction (322 +/- 182IU), decreased %Tl-201 uptake in QS region (65 +/- 7%) significantly less than the normal range, large size of region of infarction (214 +/- 83 degree) and abnormal QS in ECG (V1-3QS; 2 cases, V1-4QS; 8 cases, V1-5QS; 1 case). Improvement of wall motion in region of infarction was noted in 9 cases. Patients in group B showed an increase in serum GOT (651 +/- 382 IU p; ns), %Tl-201 uptake in QS region (48 +/- 7% p greater than 0.001) significantly less than the %Tl-201 uptake in group A, size of defects (243 +/- 45 p; ns) and abnormal QS in ECG (V1-3QS; 1 case, V1-4QS; 7 cases V1-5QS; 1 case). Improvement of wall motion was noted in 2 cases. The study showed that %Tl-201 uptake in region of infarction in patients with well EF was significantly more than that in patients with depressed EF. Mechanism of maintaining well EF after PTCR was suggested as the following, i.e. in the region released from severe ischemic attack part of myocardium resulted in necrosis, accompanying elevation of serum enzyme and appearance of QS, though part of myocardium might be salvaged from necrosis and contribute to EF in chronic phase. It has been generally thought that abnormal QS waves noted in anterior chest leads of ECG in chronic phase indicated transmural myocardial infarction in the anterior region. From this study it was concluded that QS region with %Tl-201 more than 50% did not generally correspond to transmural myocardial necrosis and that for estimation of myocardial viability %Tl-201 uptake might be more useful than ECG.