Assessment of the Ischaemic Effects of Myocardial Bridge by Echocardiographic Exercise Stress Test
Priscilla Lamendola1, Nello Cambise2, Antonio Di Renzo2
1Department of Cardiovascular Sciences, Fondazione Policlinico Universatario A Gemelli IRCCS Rome, Italy.
Insights
Myocardial bridges (MB) did not cause significant myocardial ischemia during maximal exercise. While some patients with MB showed ECG changes, echocardiography revealed no substantial ischemia, suggesting MB is unlikely to cause significant ischemia during peak exertion.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Myocardial bridges (MB) are suspected contributors to angina in patients with non-obstructive coronary artery disease.
- Limited evidence exists directly linking MB to myocardial ischemia.
Purpose of the Study:
- To investigate whether myocardial bridges (MB) cause myocardial ischemia during maximal exercise.
- To assess the impact of MB on left ventricular function and strain during stress testing.
Main Methods:
- 41 patients with left anterior descending MB and 41 controls underwent maximal treadmill exercise stress tests (EST).
- Standard and speckle-tracking echocardiography were performed at baseline and peak EST.
- ECG monitoring was used to detect ischemic changes.
Main Results:
- Positive EST (ST depression >1mm) occurred in 43.9% of MB patients versus 0% of controls (p=0.001).
- No significant differences in left ventricular systolic or diastolic function were observed between groups.
- A minor increase in global longitudinal strain (LS) during EST was noted in MB patients, with significant differences in anterior segments.
Conclusions:
- The study findings do not support the hypothesis that myocardial bridges cause significant myocardial ischemia during maximal exertion.
- Despite positive ECG stress tests in some MB patients, objective measures of ischemia were not significantly elevated.
Background:
Detection of myocardial bridge (MB) at angiography suggests it has a role in ischaemic-related symptoms in patients with angina without obstructive coronary artery disease. However, evidence that MB may cause myocardial ischaemia is limited.
Methods:
We studied 41 patients with MB of the left anterior descending coronary artery and otherwise normal coronary arteries. Fourteen patients with normal coronary arteries and without MB served as controls. All subjects underwent a maximal treadmill exercise stress test (EST) under ECG monitoring. Standard and speckle-tracking echocardiography were performed at baseline and immediately after peak EST.
Results:
EST duration and peak heart rate and systolic pressure were similar in the two groups. A positive EST (ST-segment depression .1 mm) was found in 18 patients in the MB group (43.9%) and none in the control group (p=0.001). No abnormalities in both left ventricle systolic and diastolic function were found between the two groups in the standard echocardiographic evaluation. Global and segmental (anterior, inferior) longitudinal strain (LS) did not differ at baseline between the groups. There was a small increase in global LS during EST in MB patients but not in the control group (p=0.01). Similar trends were found for regional LSs, with differences being significant for the medium (p=0.028) and apical (p=0.032) anterior segments. No differences in echocardiographic parameters and both global and segmental LSs were observed between MB patients with ischaemic ECG changes during EST versus those without.
Conclusion:
Our findings do not support the notion that MB results in significant degrees of myocardial ischaemia during maximal myocardial work.
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