Abstract
Introduction
Myocardial bridge is a rare coronary anomaly that is generally considered to be benign. The true incidence and long-term prognosis are still under debate. Therefore, we investigated the prevalence and prognosis of patients with isolated myocardial bridge in our center.
Method
This study is a retrospective, angiographic follow-up which includes 14,250 patients. Median follow-up was 4 years. The typical angiographic finding of myocardial bridging (MB) is systolic narrowing of an epicardial artery. Exclusion criterion was myocardial bridge with coronary artery disease (CAD). The primary end point was major cardiac events (death, myocardial infarction, and revascularization).
Results
Myocardial bridge was observed in 118 (0.83%) patients without CAD. The median age was 56.2. There were 30 (25.5%) male and 88 (74.5%) female patients. The arterial segment that was most frequently involved was the left anterior descending artery, as evident in 91 patients (77.2%). Most of the myocardial bridge produces a systolic narrowing between 30% and 50%. There was no major adverse cardiac event nor a need for any revascularization in the follow-up period with medical treatment.
Conclusion
Isolated myocardial bridge is a benign and rare coronary anomaly. However, further studies are needed to detect long-term prognosis.
1
Introduction
Myocardial bridging (MB) is a congenital coronary abnormality . It is defined as a segment of a major epicardial coronary artery, the ‘tunneled artery,’ that goes intramurally through the myocardium beneath the muscle bridge. MB was recognized at autopsy by Reyman in 1737 and was first described angiographically by Portmann and Iwig in 1960. It is generally confined to the mid left anterior descending coronary artery (LAD) , and the main angiographic finding is systolic compression of the involved epicardial coronary artery . Quantitative coronary angiography , intracoronary Doppler studies, and intravascular ultrasonography have documented a characteristic diastolic flow disturbance. The degree of coronary obstruction by MB depends on such factors as location, thickness, length of the muscle bridge, and degree of cardiac contractility. The estimated frequency that has been reported varies from 1.5% to 16% when assessed by coronary angiography, but in some autopsy series, it is as high as 80% . Traditionally, MB has been considered a benign condition, but the following complications have been reported: ischemia and acute coronary syndromes , coronary spasm , ventricular septal rupture , arrhythmias , exercise-induced atrioventricular conduction block , stunning , transient ventricular dysfunction , early death after cardiac transplantation , and sudden death .
In this trial, we aim to find the prevalence and prognosis of isolated MB patients who underwent coronary angiography for any reason as well as their clinical characteristics in the southern part of Turkey.
2
Methods
We reviewed the database of the cardiac catheterization laboratory of a high-volume heart center in Antalya, Turkey. All patients who underwent coronary angiography from 2002 to 2006 were included. The catheterization reports were analyzed, and those with MB were selected for further assessment. The films were reviewed by two independent investigators. In case of any difference of opinion, a consensus was reached after discussion. MB is defined as the systolic narrowing of an epicardial artery. Exclusion criterion was muscular bridge with coronary artery disease (CAD). All the patients gave their informed consent to participate in this research project, which was approved by the Ethics Committee of Başkent University School of Medicine.
The study included 14,250 patients who underwent routine coronary arteriography during the 4-year study interval to determine the incidence of isolated MB. We noted the age, sex, indication of coronary angiography, diagnostic tests before angiography, MB localization, and systolic narrowing degree from the patients’ file and cardiac catheterization laboratory. The prognosis and cardiac events were observed from the patients’ file and phone calls with patients.
2.1
Statistical analyses
Data are expressed as mean±S.D. or as proportions. The SPSS 11.5 software (SPSS, Inc., Chicago, IL, USA) was used for statistical analysis.
2
Methods
We reviewed the database of the cardiac catheterization laboratory of a high-volume heart center in Antalya, Turkey. All patients who underwent coronary angiography from 2002 to 2006 were included. The catheterization reports were analyzed, and those with MB were selected for further assessment. The films were reviewed by two independent investigators. In case of any difference of opinion, a consensus was reached after discussion. MB is defined as the systolic narrowing of an epicardial artery. Exclusion criterion was muscular bridge with coronary artery disease (CAD). All the patients gave their informed consent to participate in this research project, which was approved by the Ethics Committee of Başkent University School of Medicine.
The study included 14,250 patients who underwent routine coronary arteriography during the 4-year study interval to determine the incidence of isolated MB. We noted the age, sex, indication of coronary angiography, diagnostic tests before angiography, MB localization, and systolic narrowing degree from the patients’ file and cardiac catheterization laboratory. The prognosis and cardiac events were observed from the patients’ file and phone calls with patients.
2.1
Statistical analyses
Data are expressed as mean±S.D. or as proportions. The SPSS 11.5 software (SPSS, Inc., Chicago, IL, USA) was used for statistical analysis.
3
Results
The study population was composed of 118 patients with MB without CAD. The median age was 56.2 years. There were 30 (25.5%) male (M) and 88 (74.5%) female (F) patients ( Table 1 ). Thirty-two patients (18 F, 14 M) have hypertension, 16 (10 F, 6 M) have diabetes mellitus, and 46 (33 F, 13 M) were smoking. The incidence of isolated MB in patients who underwent routine coronary arteriography during the 4-year study interval was found to be 0.83%. Coronary angiography was performed due to positive treadmill test in 72 (64%) patients, positive myocardial perfusion imaging in 11 (10%) patients, and electrocardiographic and clinical findings in 30 (26%) patients. Most of the treadmill test results (72%) were nondiagnostic, and an upsloping ST depression was usually observed. In addition, most of the ECG findings were abnormal (96%) and a T-inversion was usually observed instead of an ST depression. The most frequently involved segment in our study population was the LAD, which was evident in 91 patients (77.2%). The second involved artery was circumflex coronary artery (Cx) obtuse marginalis (OM) 2, as detected in nine patients (7.7%). Other coronary segments are, consequently, the Cx artery trunk, the diagonal (d) 1 branch of the LAD, the posterior descending (Pd) branch of the right coronary artery (RCA), the intermediate (IM) coronary artery, and the Cx OM1 branch ( Table 2 ). Myocardial bridges mostly produce systolic narrowing between 30% and 50% in our patient group. Seventy-six (64.4%) of 118 isolated myocardial bridges have a systolic narrowing between 30% and 50%. Only 19 (16.1%) of them have a systolic narrowing over 50%. Of these, only seven patients have 80% systolic narrowing, six of the LAD and one of the RCA Pd ( Table 3 ). Median follow-up period was 4 years. There was no major cardiac event in the study population. We had used only medical treatment for these patients since 2002. There was no need for coronary artery binding graft operation and PTCA. Fifty-two of them have been treated with beta blockers, 25 with calcium channel blockers, 14 with both of them, and 27 received no therapy.
| Number of patients | Incidence | Angiographic incidence | |
|---|---|---|---|
| Male | 30 | 25.5% | 0.21% |
| Female | 88 | 74.5% | 0.62% |
| Total | 118 | 100% | 0.83% |
| Segment | Number | % |
|---|---|---|
| LAD | 91 | 77.2 |
| Cx OM2 | 9 | 7.7 |
| Cx trunk | 8 | 6.7 |
| LAD D1 | 4 | 3.4 |
| RCA Pd | 3 | 2.6 |
| Cx OM1 | 1 | 0.8 |
| IM | 2 | 1.6 |
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