Prevalence of Myocardial Bridging in Patients with Takotsubo Cardiomyopathy Chris Cianci, DO, Gautam Patankar, MD, Jeffrey Schussler, MD Baylor University Medical Center, Dallas, Texas  Introduction  Images  Discussion Takotsubo cardiomyopathy, also known as broken heart syndrome, apical ballooning syndrome, and stress-induced cardiomyopathy, is an increasingly recognized entity characterized by transient left ventricular systolic dysfunction. While the clinical presentation often mimics acute coronary syndrome, the angiogram typically lacks obstructive coronary lesions. However, an association between Takotsubo cardiomyopathy patients and myocardial bridging has recently been reported. While, myocardial bridging has been considered a normal variant with no hemodynamic relevance, this study was designed to explore the hypothesis that the incidence of Takotsubo cardiomyopathy is the result of underlying myocardial bridging and represents a pathological substrate of Takotsubo cardiomyopathy. takotsubo spasm bridging Takotsubo cardiomyopathy is a syndrome is characterized by a reversible left ventricular (LV) wall motion precipitated by stressful event, in the absence of coronary artery occlusion.1 Although the pathophysiology of Takotsubo cardiomyopathy is not still well understood several mechanisms have been proposed such as catecholamine-induced myocardial stunning, ischemia-mediated stunning, and coronary emboli with spontaneous fibrinolysis or microvascular dysfunction.1-5 Although the epicardial coronary arteries are usually normal, the association of Takotsubo cardiomyopathy with myocardial bridging (MB) has been previously reported.6 Recently, we evaluated the prevalence and potential role of MB in the pathogenesis of Takotsubo cardiomyopathy. The results of our retrospective study suggested that MB of the LAD is a very frequent finding in Takotsubo cardiomyopathy patients, as revealed by conventional coronary angiography (CA). Our results show that over 95% of our patients had evidence of myocardial bridging which primarily affected the LAD. Although the majority of our patients had less than 50% narrowing of the coronary artery, this is consistent with previous reports that show dynamic compression of the vessel can occur in segments without fully overlying muscle.7 Pathophysiologically, myocardial bridging induced ischemia may be attributed to a combination of different factors: sudden tachycardia, increased contractility, coronary spasm and systolic kinking of the coronary arteries. 8-12 Figure 1. Baseline Clinical Characteristics of the Study Population on Admission Age, yrs 67 +/- 16 Female 84 Body Mass Index 25.8+/-5.7 Coronary Risk Factors Hypertension 52 Hyperlipidemia 32 Family history of coronary disease 6 Current/History of smoking 23 Diabetes Mellitus 7 Atrial Fibrillation Depression/Anxiety 22 History of Cancer 10 Medications on Admission Aspirin 24 Warfarin 1 Beta-blockers 30 Angiotensin-converting enzyme inhibitors 20 Angiotensin II receptor blockers 15 Diuretics Digoxin 4 Oral Hyperglycemic Agent Benzodiazepine 5 Serotonin Reuptake Inhibitor 17 Clinical Presentation Chest pain 39 Dyspnea 12 Shock 8 Palpitations Syncope Stressful Event reported Emotional or Physical Peak Troponin I, ug/l 4.6 +/- 8.1 Figure 2. Prevalence and Morphological Characteristics of Myocardial Bridging by Coronary Angiography Bridging Grade Grade I 79 Grade II 2 Grade III Location LAD 77 Proximal LAD 13 Mid LAD 49 Distal LAD Left Circumflex Artery 5 Right Coronary Artery 1  Methods Study population: We reviewed the angiograms of 87 Takotsubo cardiomyopathy patients referred for cardiac catheterization at Baylor University Medical Center from 2005 to 2013. (Please see Figure 1.) Cardiac catheterization: Myocardial bridging was diagnosed if a dynamic compression of a coronary artery was observed during systole. Severity of bridging was assessed by the angiographic degree of systolic compression and as follows: Grade 1 (less than 50% narrowing), Grade 2 (50 to 75% narrowing), Grade 3 (more than 75% narrowing)  References 1. Tsuchihashi K, Ueshima K, Uchida T, et al. Transient left ventricular apical ballooning without coronary artery stenosis: a novel heart syndrome mimicking acute myocardial infarction. Angina Pectoris–Myocardial Infarction Investigations in Japan. J Am Coll Cardiol 2001;38:11– 8. 2. Prasad A, Lerman A, Rihal CS. Apical ballooning syndrome (Tako-Tsubo or stress cardiomyopathy): a mimic of acute myocardial infarction. Am Heart J 2008;155:408 –17. 3. Wittstein IS, Thiemann DR, Lima JA, et al. Neurohumoral features of myocardial stunning due to sudden emotional stress. N Engl J Med 2005; 352:539–48. 4. Iba´ñez B, Navarro F, Cordoba M, et al. Tako-tsubo transient left ventricular apical ballooning: is intravascular ultrasound the key to resolve the enigma? Heart 2005;91:102– 4. 5. Bybee KA, Murphy J, Prasad A, et al. Acute impairment of regional myocardial glucose uptake in the apical ballooning (takotsubo) syndrome. J Nucl Cardiol. 2006;13:244 –50. 6. Lemaitre F, Close L, Yarol N, et al. Role of myocardial bridging in the apical localization of stress cardiomyopathy. Acta Cardiol 2006;61: 545–50. 7. Möhlenkamp S, Hort W, Ge J, et al. Update on myocardial bridging. Circulation 2002;106:2616 –22. 8. Erbel R, Ge J Möhlenkamp S. Myocardial bridging: a congenital variant as an anatomic risk factor for myocardial infarction? Circulation 2009;120; 357–59. 9. Ferreira AG Jr., Trotter SE, König B Jr., et al. Myocardial bridges: morphological and functional aspects. Br Heart J 1991;66:364–67. 10. Bourassa MG, Butnaru A, Lespérance J, et al. Symptomatic myocardial bridges: overview of ischemic mechanisms and current diagnsotic and treatment strategies. J Am Coll Cardiol 2003;41:351–9. 11. Gaibazzi N, Reverberi C. Falsepositive stress tests. . . or false negative rest angiograms? J Am Coll Cardiol 2009;54:e9. 12. Kim PJ, Hur G, Kim SY, et al. Frequency of myocardial bridges and dynamic compression of epicardial coronary arteries: a comparison between computed tomography and invasive coronary angiography. Circulation 2009;119:1408 –16.  Results Myocardial bridging was observed in 83 of the 87 patients with Takotsubo cardiomyopathy (95%). 79 of the 83 patients had Grade 1 bridging (95%). There were 2 patients that had Grade 2 bridging (2.5%)and 2 patients with Grade 3 bridging (2.5%). The LAD was the most common coronary artery involved.                                    