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[Effects of infarcted myocardium on coronary flow reserve: a study by transesophageal Doppler echocardiography]
N Tanaka1, J Yoshikawa, K Yoshida
1Department of Cardiology, Kobe General Hospital.
Insights
Myocardial infarction impairs coronary flow reserve, particularly when salvaged myocardium is absent. Transesophageal echocardiography effectively assesses this coronary microvascular dysfunction in patients post-infarction.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Medical Imaging
Background:
- Coronary flow reserve (CFR) impairment can occur due to myocardial or microvascular disorders, even without epicardial coronary artery stenosis.
- Assessing the impact of infarcted myocardium on CFR is crucial for understanding post-myocardial infarction cardiac function.
Purpose of the Study:
- To investigate the influence of infarcted myocardium on coronary flow reserve in patients with anterior myocardial infarction.
- To evaluate the utility of transesophageal echocardiography in assessing CFR in this patient population.
Main Methods:
- Transesophageal echocardiography was used to measure coronary blood flow velocity in the left anterior descending coronary artery (LAD) in 15 patients with chronic anterior myocardial infarction.
- Patients were categorized into groups based on the presence (Group II) or absence (Group I) of salvaged myocardium, confirmed by 201Tl scintigraphy.
- Coronary flow reserve indices (P-CFR and M-CFR) were calculated by comparing hyperemic to baseline diastolic velocities before and after dipyridamole administration.
Main Results:
- Coronary flow reserve was significantly reduced in patients with myocardial infarction compared to controls.
- Patients without salvaged myocardium (Group I) exhibited lower P-CFR (1.7 ± 0.3) and M-CFR (1.5 ± 0.4) compared to those with salvaged myocardium (Group II: P-CFR 2.9 ± 0.5, M-CFR 2.7 ± 0.6).
- Control subjects showed higher P-CFR (3.8 ± 0.9) and M-CFR (3.9 ± 1.7).
Conclusions:
- Infarcted myocardium significantly influences coronary flow reserve, with a more pronounced effect observed in the absence of myocardial salvage.
- Transesophageal echocardiography is a valuable tool for assessing coronary flow reserve and microvascular function in the chronic phase of myocardial infarction.
Abstract:
Myocardial disorder or microvascular disorder can cause impairment of coronary flow reserve in patients without epicardial coronary artery stenosis. This study investigated whether infarcted myocardium influences the coronary flow reserve using transesophageal echocardiography. The coronary flow reserve was examined in 15 patients with anterior myocardial infarction without residual coronary artery stenosis in the chronic phase. The patients underwent 201Tl scintigraphy and were classified into two groups. Group I included six patients without salvaged myocardium and group II included nine patients with salvaged myocardium. The coronary blood flow velocity at the proximal part of the left anterior descending coronary artery (LAD) was evaluated by transesophageal echocardiography before and after dipyridamole administration (0.56 mg/kg/4 min). The ratios of the diastolic peak and mean velocities at hyperemia versus baseline were used as indices of coronary flow reserve (P-CFR and M-CFR, respectively). P-CFR and M-CFR were 1.7 +/- 0.3 and 1.5 +/- 0.4 in group I, and 2.9 +/- 0.5 and 2.7 +/- 0.6 in group II, respectively. Control subjects (n = 7) had P-CFR and M-CFR of 3.8 +/- 0.9 and 3.9 +/- 1.7, respectively. Coronary flow reserve decreased in patients with myocardial infarction, especially in patients without salvaged myocardium in the infarcted area. Infarcted myocardium has an important influence on coronary flow reserve, and transesophageal echocardiography is useful for evaluating coronary flow reserve.