Letter to the Editor The importance of evaluating patients with MINOCA (myocardial infarction with non-obstructive coronary arteries) Abdul Rauf Sheikh a,b , Samuel Sidharta a,c , Matthew I. Worthley a,c , Richard Yeend c , David P. Di Fiore a,b , John F. Beltrame a,b, ⁎ a Discipline of Medicine, University of Adelaide, Adelaide, South Australia 5011, Australia b Cardiology Unit, The Queen Elizabeth Hospital, Central Adelaide Local Health Network, 28 Woodville Road, Woodville South, South Australia 5011, Australia c Cardiology Unit, Royal Adelaide Hospital, Central Adelaide Local Health Network, North Terrace, Adelaide, SA 5000, Australia article info Article history: Received 6 July 2015 Accepted 7 July 2015 Available online 11 July 2015 Keywords: MINOCA Myocardial bridge Vasospastic angina Microvascular dysfunction Coronary artery disease Hyperemic microvascular resistance Acute myocardial infarction (AMI) is associated with obstructive coronary artery disease (i.e. ≥ 50% stenosis) in over 90% of patients un- dergoing angiography [1]. These patients have well-established thera- peutic guidelines, which often involve coronary revascularization. However those patients with AMI with non-obstructive coronary arteries (MINOCA) present a therapeutic predicament since coronary revascularization is not appropriate and the etiology of the infarct is not immediately apparent, yet there are no therapeutic guidelines relat- ing to the management of these patients [2]. However, identifying the etiology of MINOCA is key in the management of these patients as illus- trated by this case history of a 44-year old male with recurrent chest pain, who experienced two non-ST elevation myocardial infarctions (NSTEMIs) despite the absence of obstructive coronary artery disease (CAD). In December 2012, he first experienced significant chest pain. His coronary risk factors included being an ex-smoker, hypertension and a family history of premature coronary artery disease. On admission to hospital, he was noted to have non-specific ST depression but serial tro- ponins excluded AMI. A coronary CT angiogram found no evidence of obstructive CAD, so he was diagnosed with unstable angina and man- aged with calcium channel blocker (CCB). Over the ensuing 12 months, he continued to experience recurrent chest pain prompting investiga- tions for non-cardiac causes. Pulmonary embolism, gastro-esophageal reflux and esophageal spasm, were all excluded with pertinent investigations. In November 2013, he presented to the emergency department with a prolonged chest pain with subsequent ECGs and troponins confirming an inferior NSTEMI. Invasive coronary angiography was undertaken and confirmed the diagnosis of MINOCA. It also demonstrated the presence of a myocardial bridge (MB) producing dynamic compression of the mid-left anterior descending (LAD) artery. Cardiac MRI confirmed a small inferobasal sub-endocardial infarct. He was discharged on incre- mental CCB and nitrates but continued to experience recurrent episodes of angina. One month later, he re-presented with NSTEMI. Invasive angiogra- phy was repeated and demonstrated similar findings to the previous study. Following discharge he continued to experience recurrent angina unresponsive to the combination of beta-blocker, CCB and nitrates. He was therefore referred for invasive coronary hemodynamic testing. The objective of the testing was to assess: (i) the hemodynamic sig- nificance of the MB, (ii) the presence of coronary microvascular dys- function, and (iii) the predilection to large vessel coronary spasm. Upon cessation of vasoactive agents for 36 h, a 5 F right radial artery ap- proach was used with diagnostic images again confirming the absence of obstructive CAD. A 5 F temporary pacing electrode (required for pro- vocative spasm testing) was inserted into the right ventricle via a cubital vein approach and the threshold set to 50 bpm. The mid-LAD MB was again evident and visually appeared to be oc- clusive (Fig. 1). An intracoronary combined pressure and flow velocity wire ‘Combowire’ (Volcano Corporation, San Diego, CA, USA) was ad- vanced to the LAD. Coronary Doppler blood flow velocity was continu- ously measured with resting recordings specifically made proximal and distal to the MB. The proximal recording showed the characteristic ‘fingertip’ phenomenon associated with a MB (video-1), which disap- peared once the wire tip was advanced beyond the MB. In addition to the qualitative assessment of the MB, quantitative measures were undertaken utilizing derived velocity and pressure mea- surements at maximal hyperemia. Accordingly, using intravenous aden- osine at 170 μg/kg/min, coronary flow reserve (CFR), fractional flow reserve (FFR) and hyperemic microvascular resistance (HMR) were International Journal of Cardiology 199 (2015) 386–388 ⁎ Corresponding author at: The Queen Elizabeth Hospital, Discipline of Medicine, University of Adelaide, 28 Woodville Road, Woodville South, SA 5011, Australia. E-mail address: john.beltrame@adelaide.edu.au (J.F. Beltrame). http://dx.doi.org/10.1016/j.ijcard.2015.07.035 0167-5273/Crown Copyright © 2015 Published by Elsevier Ireland Ltd. All rights reserved. Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard