Cardiac Magnetic Resonance Improves Diagnosis in Cardiac Arrest Survivors

Cardiac magnetic resonance was superior to transthoracic echocardiogram in identifying a pathologic substrate in patients with out-of-hospital cardiac arrest.

In a retrospective study published in Resuscitation, researchers from the University of Padua in Italy and the University of Bristol in the United Kingdom found that cardiac magnetic resonance (CMR) led to a change in diagnosis, treatment, or both in 70% of out-of-hospital cardiac arrest (OHCA) survivors.1

Each year, an estimated 424,000 Americans experience nontraumatic OHCA, which is the top cause of death in the world.2 The majority of OHCA cases are caused by acute coronary syndromes (ACS), and American Heart Association and European guidelines recommend urgent angiography with a view to revascularization in resuscitated patients with suspected ACS.3,4 Evidence of ACS is observed in only 30% to 40% of patients, however, and up to 30% of cases are linked to causes other than acute ischemia.5,6

“While evidence of culprit lesion on angiogram supports acute ischemia as the cause of OHCA, diagnosis and clinical management of OHCA survivors with inconclusive coronary angiogram (either non-identifiable culprit lesion or unobstructed coronary arteries) is challenging,” the researchers wrote. They investigated the use of CMR in the diagnosis and management of 110 such patients (63% male; median age, 58) who underwent angiogram followed by CMR at 2 tertiary cardiac centers. 

Clinicians who were blinded to the CMR findings used pre-CMR imaging and clinical data to diagnose participants. CMR was considered to have a “clinical impact” if it led to a change in diagnosis, treatment, or both. 

CMR was found to be superior to transthoracic echocardiogram in identifying a pathologic substrate (69% vs 54%; P =.018), showing ischemic and nonischemic heart disease in 41% and 28% of patients, respectively. 

CMR demonstrated a clinical effect in 70% of patients, leading to a change in diagnosis (25%), management (29%), or both (16%). Findings were nonspecific in 8% of patients, and 23% had a structurally normal heart.

Accurate identification of OHCA etiology “plays a determinant role for appropriate treatment strategy and long-term prognosis,” the authors wrote. “CMR has a well-established diagnostic role, both in the ischemic and non-ischemic scenario, based on its superior tissue characterization properties,” and its use should be considered more often.


Dr Bucciarelli-Ducci is a consultant for Circle Cardiovascular Imaging, producer of the software used to assess ventricular function in the study. There are no additional disclosures.

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