Microvascular Obstruction unveiled by Cardiac MRI in Severe Coronary Vasospasm

Presenting Author(s)

• 

  Felipe Soares Torres, MD, PhD

  Assistant Professor, Cardiothoracic Imaging Division Lead - Medical Imaging Department
  University of Toronto / University Medical Imaging Toronto
  Toronto, Ontario, Canada

Primary Author(s)

• 

  Felipe Soares Torres, MD, PhD

  Assistant Professor, Cardiothoracic Imaging Division Lead - Medical Imaging Department
  University of Toronto / University Medical Imaging Toronto
  Toronto, Ontario, Canada

Co-Author(s)

• 

  Elsie T. Nguyen, MD

  Professor of Radiology
  Department of Medical Imaging, University of Toronto
  Toronto, Ontario, Canada
• KH

  Kate Hanneman, MD, MPH

  Radiologist
  Toronto General Hospital
  Toronto, Ontario, Canada
• SC

  Sean Cai, MD

  Clinical Associate
  Toronto General Hospital
  Toronto, Ontario, Canada
• VD

  Vlad Dzavik, MD

  Professor of Medicine
  University Health Network
  Toronto, Ontario, Canada

Description of Clinical Presentation: 68 y.o. female with metastatic pancreatic adenocarcinoma presented with fever, nausea, and intermittent chest pain, with elevated troponins (7960 ng/L). ECG showed new T-wave inversion in V3-V6. An outpatient coronary CT angiography performed 2 weeks prior showed CADRADS 1. An echocardiogram performed shortly after admission showed normal ventricular function and wall motion, without evidence of infective endocarditis or LV thrombus. The patient was referred to Cardiac MRI for further evaluation.

Diagnostic Techniques and Their Most Important Findings: Cardiac MRI performed using a 1.5T magnet revealed mild hypokinesis of the basal lateral wall, with corresponding focal elevation in native T1 and T2 times and transmural late gadolinium enhancement, associated with signs of microvascular obstruction (MVO). Findings were consistent with an acute myocardial infarction (Figure 1) of the basal lateral wall. Subsequent conventional coronary angiography confirmed the absence of obstructive coronary artery disease or coronary emboli. However, physiologic study demonstrated significantly reduced coronary flow reserve (CFR) at 1.6, suggesting microvascular disease. A provocative test with intracoronary acetylcholine demonstrated significant spasm of the left anterior descending coronary artery (Figure 2) accompanied by chest pain and ischemic ST changes on the ECG, confirming diagnosis of vasospastic angina.

Learning Points from this Case: Coronary vasospasm is a rare cause of acute coronary syndrome and can be triggered by stress or systemic inflammation. Cardiac MRI in patients suspected of myocardial infarction and non-obstructive coronary artery disease (MINOCA) can demonstrate the manifestations of acute MI, narrow the differential diagnosis and unveil important prognostic information, such as MVO.

Figure 1: Short axis oblique views of native T1 (A) and T2 (B) maps, post-contrast cine Steady-State Free Precession (C) and late gadolinium enhancement (D) of a 68-year-old female patient. Elevated native T1 and T2 times in the inferolateral wall (arrows in A and B, respectively) are demonstrated, as well as evidence of transmural infarction with signs of microvascular obstruction (arrows in C and D, asterisk in D).
Figure 2: Conventional coronary angiography of a 68-year-old female patient before (A) and during (B) intracoronary acetylcholine provocation test. At the 100-mcg dose (B), the patient developed chest pain, ischemic ST changes on the ECG, and angiographic evidence of significant diffuse mid-to-distal LAD vasospasm (arrows in B).