Acute myocardial infarction related to myocardial bridging

Myocardial Bridging: Review on the Role of Coronary Computed Tomography Angiography

Myocardial bridging (MB) is a congenital coronary anomaly in which a segment of a coronary artery, most frequently the left anterior descending artery, deviates from its epicardial route by passing through the myocardium. The advent of cardiac computed tomography angiography (CCTA), equipped with its multiplane and three-dimensional functionalities, has notably enhanced the ability to identify MBs. Furthermore, novel post-processing methods have recently emerged to extract functional insights from anatomical evaluations. MB is generally considered a benign entity with very good survival rates; however, there is an increasing volume of evidence that certain MB characteristics may be associated with cardiovascular morbidity. This review is intended to depict the diagnostic and prognostic role of CCTA in the MB context.

Myocardial bridging on coronary CTA: an innocent bystander or a culprit in myocardial infarction?

Myocardial bridging describes the clinical entity whereby a segment of coronary artery is either partially or completely covered by surrounding myocardium. It represents the most frequent congenital coronary anomaly and has an estimated prevalence of ≤13% on angiographic series. With the emergence of cardiac computed tomography and its ability to simultaneously image the coronary arteries and also the myocardium, there has been an apparent increase in the detection rates of myocardial bridges (prevalence as high as 44%). It has now become important to evaluate their clinical significance. Myocardial bridging is generally considered a benign entity with survival rates of 97% at 5 years; however, there is now emerging evidence that certain myocardial bridge characteristics may be associated with cardiovascular morbidity. The length and depth of myocardial bridges have been associated with increased atherosclerosis, whereas the degree of systolic compression has been associated with ischemia on myocardial perfusion single-photon emission tomography. On the basis of current evidence, it appears that limiting further testing for ischemia to symptomatic patients with long and/or deep myocardial brides would be appropriate.

Long-term prognosis of non-interventionally followed patients with isolated myocardial bridge and severe systolic compression of the left anterior descending coronary artery

PURPOSE

The aim of this study was to investigate the long-term prognosis of non-interventionally followed patients with myocardial bridge and angiographic milking of the left anterior descending (LAD) coronary artery.

METHODS

All of the coronary angiography records from May 2000 to November 2007 were reevaluated and patients who had more than 70% narrowing during systole on LAD were eligible for the present study. Follow-up was carried out by physical examination, echocardiography, and treadmill exercise testing. The clinical situations of the patients, medical treatment at the time of follow-up, and experienced events (death, myocardial infarction, or revascularization) were recorded.

RESULTS

There were 59 eligible patients (44 male, 74.6%). The mean age of the patients was 54 +/- 11 years. The bridges were located in the proximal, mid, and distal portion of the LAD in 17 (28.8%), 20 (33.9%), and 22 (37.3%) patients, respectively. Distributions of the narrowing degree were as follows: between 70% to 89% in 33 (56%) patients and 90% to 100% in 26 (44%) patients. Mean follow-up duration of the group was 37 +/- 13 months (range 15-65 mo). The clinical presentation during follow-up was stable angina in 9 (15.3%) cases, atypical angina in 12 (20.3%), atypical chest pain in 13 (22%), dyspnea in 3 (5.1%), and syncope in 3 (5.1%) cases. There were no experienced events and/or hospitalizations related to cardiac disease. Echocardiographic examination revealed normal systolic ventricular function. Only 17 (28.8%) patients continued to use medication. Most of them were on beta-blocker therapy.

CONCLUSION

Patients with myocardial bridges and angiographic milking of the LAD coronary artery have a good long-term prognosis.

Comparison of frequency of coronary spasm in Korean patients with versus without myocardial bridging

The longstanding compression-relaxation effects of myocardial bridging may produce endothelial dysfunction by direct stress on the endothelium. We tested the hypothesis that myocardial bridging induces endothelial dysfunction and subsequently increases the risk of coronary spasm and investigated the symptomatic response to medication in patients with documented myocardial bridging and coronary spasm. In 81 patients with myocardial bridging (44 men; mean age 57.2 years) and 195 control patients without bridging and atherosclerotic lesions confirmed by angiography (97 men; mean age 58.4 years), spasm provocation testing was done by incremental acetylcholine infusion into the left coronary artery. Spasm was documented in 62 of 81 patients with bridging and in 31 of 195 controls (p <0.001). A focal spasm was limited to the bridging segments compared with controls (p <0.001). In conclusion, the results of this study showed that myocardial bridging increased the risk of coronary spasm by endothelial dysfunction in the bridging segment.

[Long-term prognosis of patients with myocardial bridge and angiographic milking of the left anterior descending coronary artery]

INTRODUCTION

Myocardial bridging with systolic compression (milking) of the left anterior descending coronary artery may be associated with myocardial ischemia. Little information is available about the long-term prognosis of patients with this coronary anomaly.

MATERIAL AND METHODS

A review was made of coronary angiographies of patients diagnosed as ischemic heart disease made between 1994 and 1999 in two centers. The long-term follow-up of patients with myocardial bridging and systolic compression of the left anterior descending coronary artery was analyzed. Data were collected by reviewing medical records and completed by telephone interview.

RESULTS

Prevalence: 0.72%. Milking was observed in 60 patients, but 25 of them were excluded due to associated hypertrophic cardiomyopathy, severe valvular disease, or coronary artery disease. The clinical follow-up was available for all patients (median: 43 months, range: 12-80 months). Mean age 55.7 years (SD = 11.9). Men 74%.

CLINICAL PRESENTATION

angina 26 patients, atypical chest pain with positive non-invasive test 8, acute myocardial infarction 1. During follow-up, 1 patient died of sudden cardiac death. Seven patients continued to present stable angina CCS class I-II, coronary angiography was repeated in 5 patients, and one required percutaneous revascularization for symptoms. In 63% of cases, antianginal drugs were still needed at the end of follow-up period (beta-blockers or calcium antagonists).

CONCLUSIONS

Patients with myocardial bridging and systolic compression of the left anterior descending artery have a good long-term prognosis, although more than half of them continue regular treatment with antianginal drugs. In a small percentage of cases percutaneous intervention must be performed and ischemic heart disease may appear in more aggressive forms (acute myocardial infarction or sudden death).

Long term angiographic and clinical follow up in patients with stent implantation for symptomatic myocardial bridging

OBJECTIVE

To assess long term results of coronary stent implantation in patients with symptomatic myocardial bridging.

METHODS

Intracoronary stent implantation was performed within the intramural course of the left anterior descending coronary artery in 11 patients with objective signs of myocardial ischaemia and absence of other cardiac disorders. All had myocardial bridging of the central portion of the left anterior descending coronary artery. Quantitative coronary angiography was performed before and after stent deployment, and again at seven weeks and six months. Clinical evaluation was done at two years.

RESULTS

After stent deployment, quantitative coronary angiography showed absence of systolic compression along the left anterior descending coronary artery; the minimum luminal diameter (mean (SD)) increased from 0.6 (0.3) mm before stent implantation to 1.9 (0.3) mm after implantation (p < 0. 05). Intravascular ultrasound showed an increase in cross sectional area from 3.3 (1.3) mm(2) at baseline to 6.8 (0.9) mm(2) (p < 0.005) after stent deployment. Coronary flow reserve was normalised from 2. 6 (0.5) at baseline to 4.0 (0.5) (p < 0.005) after stent implantation. At seven weeks, quantitative coronary angiography showed mild to moderate or severe in-stent stenosis in five of the 11 patients; four of these underwent repeat target vessel revascularisation (percutaneous transluminal coronary angioplasty in two; coronary artery bypass grafting in two). At six months, all patients (n = 9) showed good angiographic results, including those who had target vessel revascularisation. On clinical evaluation at two years, all patients (including those with target vessel revascularisation) remained free of angina and cardiac events.

CONCLUSIONS

Intracoronary stent implantation prevents external compression of bridged coronary artery segments, with increase in luminal diameter and alleviation of symptoms. The incidence of in-stent stenosis requiring target vessel revascularisation (36%) is comparable with that of lesions of 25 mm length in coronary artery disease. The symptom free and event free two year follow up data suggest that stent implantation is a useful way of treating symptomatic patients with myocardial bridges.

Myocardial bridging as a cause of acute transient left heart dysfunction

The significance of myocardial bridging is still a matter of debate, and although several reports have underlined its pathologic potential, myocardial bridging is often considered to be a benign phenomenon. We present here the case of a 63-year-old woman with a history of acute left heart failure and ECG evidence of ischemia, and whose primary abnormality on extensive workup was myocardial bridging. This case further underlines that myocardial bridging can lead to significant cardiac events.