ABSTRACT
Extrinsic compression of the left main coronary artery (LMCA) by a
dilated pulmonary artery (PA) in the setting of pulmonary arterial
hypertension (PAH) is an increasingly recognized disease entity. LMCA
compression has been associated with angina, arrhythmia, heart failure,
and sudden cardiac death in patients with PAH. Recent studies suggest
that at least 6% of patients with PAH have significant LMCA compression.
Screening for LMCA compression can be achieved with computed coronary
tomography angiography, with a particular emphasis on assessment of PA
size and any associated downward displacement and reduced takeoff angle
of the LMCA. Indeed, evidence of a dilated PA (>40 mm), a reduced
LMCA takeoff angle (<60°), and/or LMCA stenosis on CCTA imaging
should prompt further diagnostic evaluation. Coronary angiography in
conjunction with intravascular imaging has proven effective in
diagnosing LMCA compression and guiding subsequent treatment. While
optimal medical therapy and surgical correction remain in the
clinician's arsenal, percutaneous coronary intervention has emerged as
an effective treatment for LMCA compression. Given the prevalence of
LMCA compression, its associated morbidity, and mortality, and the wide
array of successful treatment strategies, maintaining a high degree of
suspicion for this condition, and understanding the potential treatment
strategies is critical.