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[Myocardial perfusion assessed by dynamic computed tomography, with respect to viable muscle in the infarcted region]
1First Department of Internal Medicine, Kobe University School of Medicine.
Insights
Myocardial perfusion is significantly reduced even with mild or no coronary artery stenosis, impacting heart function. This study highlights reduced flow/volume ratio in patients with various degrees of coronary stenosis and wall motion abnormalities.
Area of Science:
- Cardiovascular imaging
- Myocardial perfusion assessment
- Interventional cardiology
Background:
- Regional myocardial perfusion is crucial for understanding heart function after myocardial infarction.
- Assessing perfusion in patients with coronary artery stenosis, including those post-percutaneous transluminal coronary angioplasty (PTCA), is clinically important.
Purpose of the Study:
- To evaluate the significance of regional myocardial perfusion in patients with old myocardial infarction.
- To investigate the relationship between coronary artery stenosis severity, myocardial perfusion, and left ventricular wall motion.
Main Methods:
- Dynamic transmission computed tomography with electrocardiographic triggering was used for high-resolution imaging.
- Contrast medium was injected to assess myocardial perfusion, calculating the flow/volume (F/V) ratio.
- Patients with old myocardial infarction, including those post-PTCA, were studied.
Main Results:
- The F/V ratio, indicating perfusion per unit of myocardium, was significantly lower in patients with all degrees of coronary stenosis compared to controls.
- Abnormal perfusion findings were common even in mild or non-significant coronary stenosis.
- In mild stenosis cases, the F/V ratio correlated with the severity of left ventricular wall motion abnormalities.
Conclusions:
- Reduced myocardial perfusion is evident even with mild or absent coronary artery stenosis in patients with prior myocardial infarction.
- Myocardial perfusion assessment using dynamic CT provides valuable insights into cardiac function beyond anatomical stenosis.
- Wall motion abnormalities play a role in reduced perfusion in less severe coronary artery disease.
Abstract:
To clarify the significance of regional myocardial perfusion, 31 patients of old myocardial infarction including 11 cases undergoing PTCA with a left anterior descending artery lesion were studied using dynamic transmission computed tomography with excellent time resolution. Serial one-second dynamic scans with an electrocardiographic triggering system were performed at the middle level of the left ventricle using a bolus injection of contrast medium via the inferior vena cava. The F/V (F = flow, V = volume) ratio, a parameter of perfusion per unit of myocardium, was calculated from gamma-variate fitted time density curves obtained in the myocardium and in the left ventricular cavity. The F/V ratio was significantly lower in patients not only with severe but also mild and no coronary artery stenosis (post PTCA: 185 +/- 54, 50-75% stenosis: 193 +/- 47, 90% stenosis: 181 +/- 51, 99% stenosis: 140 +/- 34, 100% stenosis: 142 +/- 27 ml/min/100 g, control value: 243 +/- 51 ml/min/100 g, post PTCA, 50-75% stenosis, 90% stenosis vs control p less than 0.05, 99%, 100% stenosis vs control p less than 0.005). The functional images depicting myocardial perfusion frequently revealed abnormal perfusion findings in patients not only with severe but also mild and no coronary stenosis. In the patients with mild or insignificant coronary stenosis, the F/V ratio was dependent on the severity of left ventricular wall motion abnormalities (hypokinesis: 192 +/- 51, akinesis or dyskinesis: 141 +/- 32 ml/min/100 g; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)