Myocardial bridge: bridging the differential diagnosis

Myocardial Bridging, Unusual Cause of Myocardial Infarction; Case Report and Review of Literature

Myocardial bridging is a common coronary anomaly. Although it is considered to be a benign condition, it can rarely be complicated by myocardial infarction. Clinicians should be suspicious of myocardial bridging as an etiology of myocardial infarction when other more common etiologies have been excluded. High resolution CT angiography is the gold standard for diagnostic evaluation, with the length and depth of the bridge, and response to conservative therapies guiding clinical decision making on surgical correction. Myocardial bridging is a congenital coronary anomaly in which the coronary arteries pass through the heart muscle rather than lying on its surface. It is typically a benign condition, and most patients are asymptomatic. However, some may experience symptoms of angina. In rare cases, patients can present with myocardial ischemia or infarction. In this report, we present the case of a 38-year-old female who presented with a 2-month history of chest pain. Further evaluation with coronary computed tomography angiography (CCTA) revealed myocardial bridging. Subsequently, she developed a myocardial infarction, a rare complication of this condition. We discuss this uncommon complication of a common anomaly.

Myocardial Bridging-Induced Acute Coronary Syndrome: A Bridge Too Far

Recent studies suggest a potential association between myocardial bridging (MB) and accelerated atherosclerotic plaque formation. We describe the case report of a 37-year-old South Asian male with no established risk factors for coronary artery disease (CAD) who presented with a non-ST-segment-elevation acute coronary syndrome (NSTE-ACS) with a coincident widowmaker lesion and severe MB. He was successfully managed with comprehensive guideline-directed medical therapy (GDMT) and urgent percutaneous coronary intervention (PCI) of the culprit lesion, sparing the MB segment. The clinician should be cognizant of MB implicating ACS as a major adverse cardiovascular event (MACE) and its key management strategies.

Worsening of Angina Following Nitroglycerin Administration: A Case Report of the Interplay With Undiagnosed Myocardial Bridge

Myocardial bridge (MB) is a congenital abnormality where part of a coronary epicardial artery runs under the myocardium fibers and is compressed in systole; this becomes more pronounced when nitroglycerin (NTG) is administered. In this report, we describe the case of a 40-year-old African American man who presented with chest pain that did not respond to NTG or isosorbide mononitrate and was only partially relieved by narcotics. His past medical history was significant for coronary artery disease (CAD) with a stent into the left anterior descending artery (LAD) several months prior, hypertension, hyperlipidemia, paroxysmal atrial fibrillation, sick sinus syndrome, permanent pacemaker, pulmonary embolism, and cerebral vascular accident. No explanation for his angina was found either in the previous outpatient left heart catheterization (LHC) procedures demonstrating LAD stent patency or initial chest pain workup upon admission. Functional LHC procedure with adenosine infusion and acetylcholine provocation demonstrated endothelial dysfunction with notable epicardial spasm and MB of the LAD that worsened with NTG. Cardiology advised dual antiplatelet therapy and a statin as part of treatment for CAD and a calcium channel blocker with a bradycardic effect (e.g., diltiazem, verapamil) for the MB and coronary vasospasm, and avoidance of NTG and long-acting nitrates (e.g., isosorbide mononitrate), which can cause reflex tachycardia and worsen angina from MB. A selective serotonin reuptake inhibitor was added for increased cardiac nociception. The patient's pain resolved, and he was discharged. MB is an important alternate etiology to consider when chest pain does not respond to NTG administration for adjustment of treatment modalities. The initial treatment for this patient's pain with NTG likely exacerbated symptoms by reducing intrinsic coronary wall tension and subsequently increasing reflex sympathetic stimulation of contractility of the left ventricular myocardium, which can, in turn, increase anginal symptoms and ischemia.

Implications of Myocardial Bridge on Coronary Atherosclerosis and Survival

Background: In this study, we aimed to describe the impact of MBs on atherosclerosis and survival, in patients with coronary artery disease (CAD). Methods: We retrospectively studied 1920 consecutive patients who underwent conventional coronary angiography for suspected CAD. Atherosclerotic load (AL), defined as the sum of degrees of stenosis, and general atherosclerotic load (GAL), representing the sum of AL, were compared between patients with MB and a control group without MB; patients in these groups were similar in age and sex. We assessed survival at 10 years after the last enrolled patient. Results: Prevalence of MB was 3.96%, predominantly in the mid-segment of left anterior descendent artery (LAD). In the presence of MB, GAL was lower (158.1 ± 93.7 vs. 205.3 ± 117.9, p = 0.004) with a lesser AL in the proximal (30.3 ± 39.9 vs. 42.9 ± 41.1, p = 0.038) and mid-segments (8.1 ± 20.0 vs. 25.3 ± 35.9, p < 0.001) of LAD. Based on a Multinominal Logistic Regression, we found that the presence of MB on LAD (regardless of its location on this artery) is a protective factor against atherosclerotic lesions, decreasing the probability of significant stenosis, especially of those ≥70%, on the entire artery (B −1.539, OR 4660; 95% CI = 1.873−11.595, p = 0.001) and on each of its segments as well: proximal LAD (B −1.275, OR 0.280; 95% CI = 0.015−5.073; p = 0.038), mid-LAD (B −1.879, OR 6.545; 95% CI = 1.492−28.712; p = 0.013) and distal LAD (B −0.900, OR 2.459, 95% CI = 2.459−2.459, p = 0.032). However, 10-year survival was similar between groups (76.70% vs. 74.30%, p = 0.740). Conclusion: The presence of MB on LAD proved to be a protective factor against atherosclerosis for the entire artery and for each of its segments, but it does not influence long-term survival in patients with CAD.

Myocardial Bridging Unmasks as an Acute Coronary Syndrome from Dehydration

A 50-year-old male presented for loss of consciousness. He was initially treated with intravenous epinephrine and fluids, and an electrocardiogram (ECG) displayed an ST-segment elevation in lead aVR with global ST-segment depressions. A subsequent left heart catheterization revealed that the middle segment of the left anterior descending artery (LAD) demonstrated severe stenosis during systole but would become patent during diastole, which was suggestive of myocardial bridging. After stopping the epinephrine and increasing the fluid infusion, the ECG changes rapidly resolved. The patient had later admitted to significant dehydration all day. Myocardial bridging is a congenital anomaly in which a coronary artery segment courses through the myocardium instead of the usual epicardial surface. Occasionally, myocardial bridging may present similarly to acute coronary syndrome in severe dehydration or hyperadrenergic states. The diagnosis can be made through coronary angiography, which reveals a dynamic vessel obstruction pattern corresponding with the cardiac cycle. Long-term effects may also include accelerated atherosclerosis. Treatment consists of reversing precipitating causes during acute presentations and decreasing the risk of coronary artery disease on a chronic basis.

Epicardial ultrasound in a case of myocardial bridge and apical hypertrophic cardiomyopathy

A 59-year-old male with a history of unstable angina was diagnosed with a myocardial bridge of the left anterior descending artery (LAD) and apical variant hypertrophic cardiomyopathy (AHCM). He underwent unroofing of the myocardial bridge and a left ventricular apical myectomy. Intraoperatively, epicardial ultrasound was used to identify the myocardial bridge with systolic compression of the LAD and confirm resolution of this compression postoperatively. Furthermore, epicardial ultrasound was used for guiding the degree of apical resection of the decompressed heart. This novel use of intraoperative epicardial ultrasound can help guide surgeons preoperatively and confirm results immediately after an operation.