Left Anterior Descending Artery Myocardial Bridging A clinical approach Chiara Fraccaro, Md PhD Giuseppe Tarantini, Md PhD Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padova, Italy

J Am Coll Cardiol. 2016 Dec 27;68(25):2887-2899

EPIDEMIOLOGY Necropsy series 5% to 86% Angiographic detection rate 0.5% to 12% (rest) 40% (provocative tests or i.c. nitro) Factors accounting for heterogeinicity: thickness and length of the MB reciprocal orientation of the coronary artery and myocardial fibers presence of loose connective or adipose tissue around the bridged segment presence of an aortic outflow tract obstruction intrinsic tone of the coronary artery wall presence of a proximal coronary fixed obstruction state of myocardial contractility heart rate at the time of angiography observer experience

LAD Coronary Artery Myocardial Bridging Anatomic Properties

Factors that may unmask or exacerbate MB are: PATHOPHYSIOLOGY Factors that may unmask or exacerbate MB are: the age of the patient heart rate left ventricle (LV) hypertrophy and the presence of coronary atherosclerosis Interaction among Tachicardia, Coronary Artery Flow, and Transmural Distribution

CLINICAL PRESENTATION Asymptomatic incidental finding Stable exercise-induced or silent myocardial ischemia Unstable coronary spasm Thrombosis coronary dissection syndrome X myocardial stunning or transient ventricular dysfunction Takotsubo syndrome life-threatening ventricular arrhythmias sudden death

MORPHOLOGICAL ASSESSMENT CORONARY ANGIOGRAPHY (+ i.c. nitro) IVUS “half-moon phenomenon” Shin Lin et al. J Am Heart Assoc 2013 CCT

INVASIVE FUNCTIONAL ASSESSMENT The evaluation during chronotropic and inotropic stimulation is mandatory 1. Dobutamine diastolic FFR & iFR False negative using mean pressure! Diastolic FFR o iFR better!! overshooting of Pd over Pa

INVASIVE FUNCTIONAL ASSESSMENT The evaluation during chronotropic and inotropic stimulation is mandatory 1. Dobutamine diastolic FFR & iFR

INVASIVE FUNCTIONAL ASSESSMENT Doppler-tipped guidewires for measurements of intracoronary flow velocity and coronary flow reserve. retrograde flow during systole immediately proximal to the bridged segment; “fingertip phenomenon,” an abrupt early diastolic flow accel- eration, rapid mid-diastolic flow deceleration, and a mid-to-late diastolic plateau (“spike-and-dome” pattern). Heinrich G. Klues et al. Circulation. 1997;96:2905-2913

NON-INVASIVE FUNCTIONAL ASSESSMENT Stress echocardiography Stress cardiac magnetic resonance Single-photon emission computed tomography and positron emission tomography Post-processing techniques for the derivation of functional information from the anatomic assessment provided by CCT (transluminal attenuation gradient and computed tomography (CT)–derived).

MANAGEMENT STRATEGY