Myocardial infarction caused by coronary artery myocardial bridge

Lesion characteristics and prognosis of acute coronary syndrome without angiographically significant coronary artery stenosis

AIMS

While patients with acute coronary syndrome (ACS) presenting with non-obstructive coronary artery disease (CAD) are at high risk for cardiovascular mortality and morbidity, detailed lesion characteristics are unclear. The aim of this study was to investigate the lesion characteristics and prognosis of ACS with non-obstructive CAD.

METHODS AND RESULTS

This study consisted of 82 consecutive ACS patients without obstructive CAD who underwent optical coherence tomography (OCT). Based on the presence of high-risk lesions (HL) in the culprit artery, we classified the patients into two groups: HL group and non-high-risk lesions (NHL) group. A systematic clinical follow-up was performed at our outpatient clinic for up to 24 months. Our endpoint was recurrence of ACS with obstructive CAD. OCT revealed that 42 (51.2%) of 82 patients had hidden HL in the culprit artery, including ruptured plaque (15.9%), calcified nodule (11.0%), spontaneous coronary artery dissection (8.5%), lone thrombus (8.5%), thin-cap fibroatheroma (6.1%), and plaque erosion (1.2%). During angiography, 5 (11.9%) HL patients complained of chest pain without ST elevation. Patients in the HL group had poorer prognoses than those in the other groups (P = 0.040).

CONCLUSION

Hidden high-risk lesions accompany ACS patients without obstructive CAD, resulting in poorer outcomes. Vascular injury itself might provoke acute chest pain.

The electrocardiogram as an adjunct in diagnosing congenital coronary arterial anomalies

Congenital coronary arterial abnormalities as isolated lesions are exceedingly rare. The electrocardiogram, while a reasonable adjunct in the diagnosis of coronary arterial abnormalities, should not supplant a good history and physical examination. Careful attention must be devoted to any signs or symptoms of ischaemic pain in the chest or syncope, which must not be overlooked. Exertional pain in the chest and exertional syncope should prompt an extensive evaluation by both the echocardiographer and the electrophysiologist. Clearance for participation in sports should be curtailed until a complete evaluation has ruled out the presence of any of the following disorders: a channelopathic mutation, a cardiomyopathy, or a congenital coronary arterial anomaly. Major abnormalities in the coronary arteries may present in the first few months of life or remain dormant until the exertional demands of adolescence unmask symptoms of myocardial ischaemia. Congenital coronary arterial anomalies may be analysed in the following major diagnostic groups: anomalous origin of the left coronary artery from the pulmonary artery, anomalous aortic origin of a coronary artery from the wrong aortic sinus of Valsalva, atresia of the left main coronary artery, myocardial bridges, and coronary arterial fistulas. The advent of state-of-the-art modalities of imaging seems, at times, to have supplanted the electrocardiogram in making the diagnosis of potentially serious coronary artery abnormalities, especially in asymptomatic patients. However, as is also the case for a detailed history and physical examination, the electrocardiogram provides a potentially insightful look at the coronary arteries. Furthermore, the past decade has witnessed an increase in the use of the electrocardiogram as a screening tool in the assessment of the risk of sudden cardiac death in athletes in high school.

Systolic total narrowing of left anterior descending coronary artery and flow interruption secondary to myocardial bridge: a rare case report and review of literature

A 33-y-old man was admitted to the emergency department with sudden onset of severe substernal chest pain radiating to the left arm and neck. No pathological signs were recorded upon physical examination. The admission electrocardiogram (ECG) recorded during chest pain showed a large anterior wall myocardial infarction. Intravenous (IV) infusion of 1.5 million units of streptokinase over 1 h was initiated. Coronary angiography revealed total narrowing and flow interruption in the midsegment of the left anterior descending (LAD) coronary artery secondary to a myocardial bridge during systole and disappearance with diastole. He was discharged on aspirin (300 mg/d), metoprolol (100 mg/d), enalapril (10 mg twice daily), and atorvastatin (40 mg/d) treatment at the follow-up period.

Myocardial infarction with distal embolization associated with myocardial bridging in a postoperative patient: a case report

Myocardial bridging is associated with myocardial infarction (MI) on rare occasions. The mechanism by which this occurs is unclear; vessel occlusion in this setting may be due to superimposed thrombosis or vasospasm. An unusual case is presented of postoperative MI from thrombosis associated with myocardial bridging and intravascular volume depletion, with subsequent distal embolization. Endothelial injury as a result of myocardial bridging may predispose to thrombus formation. To avoid MI, adequate fluid hydration is recommended during the perioperative period in patients with myocardial bridging.

Myocardial Bridge: a clinical review

Human coronary arteries occasionally course intramyocardially--a condition termed Myocardial Bridge. We review the anatomic and pathophysiological basis of the Myocardial Bridge and discuss clinical presentations, prognoses and the current treatment options for this interesting coronary angiographic variant.

Impending acute myocardial infarction during severe exercise associated with a myocardial bridge

A young man had an impending acute myocardial infarction while playing soccer. Chest pain and anterior ST-segment elevation lasted 3 hours despite anti-ischemic medication, including streptokinase thrombolysis. An electrocardiogram recorded after the symptoms had passed was normal. There was a minimal increase in cardiac enzyme levels, and a pyrophosphate scan and echocardiogram were normal. Coronary cineangiography showed normal coronary arteries except for systolic compression of the left anterior descending coronary artery. An exercise stress test, while the patient was on atenolol, showed absence of myocardial ischemia. This impending acute myocardial infarction could have been caused by an acute thrombus with lysis prior to catheterization or by a deep muscle bridge that kinked or twisted the coronary artery due to myocardial forceful muscular contraction during the sympathetic stimulation of exercise. In conclusion, an impending acute myocardial infarction may occur in young patients having myocardial bridges, and a beta-blocker must be administered, especially when this condition appears during severe exercise.

Coronary vasospasm at the site of myocardial bridge--report of two cases

Two patients with angina pectoris and postmyocardial infarction angina due to coronary vasospasm at the site of myocardial bridge are described. Intracoronary injection of isosorbide dinitrate led to resolution of coronary vasospasm on acetylcholine provocation test, and vasospastic angina pectoris has been well controlled after treatment with calcium channel blockers.

Angina Pectoris Due to Severe Muscular Bridge in Hypertrophic Cardiomyopathy

We report the case of a 39-year-old male with hypertrophic cardiomyopathy who complained of angina pectoris. The patient was treated with a beta blocker and a calcium antagonist without effect. Myocardial scintigraphy revealed anterior ischemia. Cardiac catheterization and ventriculography revealed severe systolic narrowing of the left anterior descending coronary artery and no significant pressure gradient across the left ventricular outflow tract. Myotomy was performed on a muscular bridge over the left anterior descending coronary artery and the patient's angina was relieved. In young patients with hypertrophic cardiomyopathy who develop angina refractory to medical therapy, a coexisting muscular bridge should be sought.