Key result
In a 54-year-old male patient with a myocardial bridge, T-wave alternans area averaged 6.3 µV×s, which was at least twice as high as expected in healthy male subjects and significantly correlated with heart rate.
Why the study?
Myocardial bridge can be associated with critical cardiac events, prompting the evaluation of electrocardiographic alternans as a cardiac electrical risk index in an affected patient.
Does a myocardial bridge increase electrocardiographic alternans in a resting patient?
Case Report (n=1)
No
Does a myocardial bridge increase electrocardiographic alternans in a resting patient?
A patient with a myocardial bridge exhibited elevated T-wave alternans at rest, suggesting an increased cardiac electrical risk that correlates with heart rate.
Answers are grounded in this paper and cite their sources.
Elevated resting TWA in myocardial bridge may signal electrical instability; hypothesis-generating and requires confirmation before any clinical application.
Myocardial bridge (MB) is a congenital heart condition in which a "bridge" of myocardium is overlying a "tunneled" coronary artery. MB can be associated with a series of critical cardiac events. Aim of this study was to evaluate electrocardiographic alternans (ECGA) on a MB patient, being ECGA a cardiac electrical risk index defined as beat-to-beat alternation of electrocardiographic P-wave, QRS-complex and Twave morphology at stable heart rate. ECGA analysis was performed in a 1-hour 12-lead electrocardiographic recording of a 54 years-old MB male patient at rest by application of the heart-rate adaptive match filter method. Areas of P-wave, QRS and T-wave alternans (PWAA, QRSAA, TWAA) were measured, evaluating also the prevalent among the three. Results showed the prevalent alternans was T-wave alternans, being TWAA on average equal to 6.3 Vs (PWAA=4.7 Vs, QRSAA=4.3 Vs); TWAA prevalence occurrence rate was 94% (PWAA: 5%, QRSAA:1%). TWAA was also found to be significantly correlated (=0.72, p<10 -2 ) with heart rate. Eventually, TWAA was at least twice higher than in previously analyzed male healthy subjects. Thus, MB seems to be associated to a higher cardiac electrical risk, possibly especially while performing physical activity at high heart rate.
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Marcantoni et al. (2020) conducted a case report in Myocardial bridge (n=1). Myocardial bridge vs. Healthy male subjects (historical reference) was evaluated on T-wave alternans area (TWAA). In a 54-year-old male patient with a myocardial bridge, T-wave alternans area averaged 6.3 µV×s, which was at least twice as high as expected in healthy male subjects and significantly correlated with heart rate.
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