The left main coronary artery deserves more than a quick look

Significant left main coronary artery (LMCA) stenosis is generally defined as the presence of a more than 50% stenosis at angiography. It is found in approximately 4% of patients undergoing diagnostic coronary angiography [1]. It is widely accepted that a significant narrowing of the LMCA puts a patient at high risk, as the stenosis jeopardizes almost the entire left ventricle. The current guidelines categorize the use of coronary artery bypass graft (CABG) for revascularization of patients with unprotected LMCA disease as a class IA recommendation, while they categorize the use of percutaneous coronary interventions (PCIs) as a class IIb or III recommendation [2,3]. Moreover, according to the existing guidelines, any stenosis of the LMCA of more than 50% should be treated surgically, regardless of the presence of symptoms or objective signs of ischemia [4]. These recommendations are based on studies conducted several decades ago when medical and surgical treatment practices were markedly different from current practice [5–7]. In addition, PCI has emerged as an alternative form of revascularization and its role in the treatment of LMCA stenoses is currently being investigated in prospective randomized trials. Yet, relatively little attention is paid to what should be the very first step of a patient-centered decision-making process: the precise diagnosis. The debate rages on how to treat prior to defining what exactly should be treated.