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Dobutamine-induced wall motion abnormalities: correlations with myocardial fractional flow reserve and quantitative
J Bartunek1, T H Marwick, A C Rodrigues
1Cardiovascular Center, Aalst, Belgium.
Insights
Dobutamine echocardiography accurately detects coronary stenosis severity, but its sensitivity decreases with smaller vessel diameters and depends on the area at risk. Myocardial fractional flow reserve is a better correlate of wall motion abnormalities.
Area of Science:
- Cardiology
- Diagnostic Imaging
- Echocardiography
Background:
- Traditional assessment of dobutamine echocardiography accuracy relies on stenosis geometry.
- Myocardial fractional flow reserve (FFR) offers a functional index of stenosis severity, considering flow dynamics.
Purpose of the Study:
- To evaluate the relationship between dobutamine-induced wall motion abnormalities and coronary stenosis features.
- To assess the impact of the area at risk on dobutamine echocardiography sensitivity.
Main Methods:
- 75 patients with coronary stenosis underwent dobutamine echocardiography, quantitative coronary angiography, and pressure measurements.
- Myocardial fractional flow reserve was calculated as the ratio of distal coronary to aortic pressure during hyperemia.
Main Results:
- Dobutamine-induced dyssynergy correlated significantly with stenosis severity (diameter, area, minimal lumen diameter) and FFR.
- Sensitivity for detecting significant lesions was 83% (diameter stenosis ≥50%) and 80% (minimal lumen diameter ≤1 mm).
- Sensitivity was significantly lower in smaller vessels (reference diameter ≤2.6 mm) for functionally significant stenoses (FFR ≤0.75).
Conclusions:
- Dobutamine-induced wall motion abnormalities correlate with stenosis severity, with FFR being a closer correlate.
- The extent of myocardium at risk critically influences dobutamine echocardiography accuracy in functionally significant stenoses.
Objectives:
This study evaluated both the relation between dobutamine-induced wall motion abnormalities and the physiologic and morphologic features of epicardial coronary artery stenoses and the impact of the extent of the area at risk on the sensitivity of dobutamine echocardiography.
Background:
The accuracy of dobutamine echocardiography has traditionally been assessed by comparing results with stenosis geometry. Myocardial fractional flow reserve is a functional index of coronary stenosis severity that takes into account both antero-grade and collateral flow and may therefore be a more appropriate standard for comparison.
Methods:
Seventy-five patients with normal left ventricular function, good echocardiographic images and an isolated coronary stenosis underwent, within 6 h, dobutamine echocardiography, quantitative coronary angiography and intracoronary pressure measurements. Myocardial fractional flow reserve was calculated as the ratio of mean hyperemic distal coronary to aortic pressure.
Results:
The degree of dobutamine-induced dyssynergy correlated significantly with percent diameter stenosis (r = 0.68), area stenosis (r = 0.68) and minimal lumen diameter (r = -0.60) and markedly better with myocardial fractional flow reserve (r = -0.77). However, marked dispersion of the individual data was observed. The sensitivity of dobutamine echocardiography in detecting lesions with a minimal lumen diameter < or = 1 mm and diameter stenosis > or = 50% was 83% and 80%, respectively. All but one patient with a myocardial fractional flow reserve >0.75 had a normal stress test result. Among patients with a myocardial fractional flow reserve < or = 0.75, the sensitivity of dobutamine echocardiography was significantly lower for lesions in vessels with a reference diameter < or = 2.6 mm than for lesions in larger vessels (58% vs. 90%, p = 0.008).
Conclusions:
1) The magnitude of wall motion abnormalities induced by dobutamine infusion correlates with angiographic and, more closely, with functional indexes of stenosis severity, even though a wide scatter is observed. 2) In patients with a functionally significant stenosis, the amount of myocardium at risk is a critical determinant of the accuracy of dobutamine echocardiography.