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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
Angiographic detection rate
5% to 86%
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
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
2. Doppler-tipped guidewires for measurements of intracoronary flow
velocity and coronary flow reserve.
a.
b.
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
1. Stress echocardiography
2. Stress cardiac magnetic resonance
3. Single-photon emission computed tomography and positron
emission tomography
4. 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