Researchers in the United Kingdom have found in a first-of-its-kind study that fibrosis detected by late gadolinium enhancement cardiac MRI may be an independent predictor of hard cardiovascular events in patients with ventricular arrhythmias.
Dana K Dawson, Cardiovascular Medicine Research Unit, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, United Kingdom, and others aimed to explore whether fibrosis detected by late gadolinium enhancement cardiac MRI is an independent predictor of hard cardiovascular events in patients with ventricular arrhythmias. “In patients at risk of sudden cardiac death, risk stratification for device therapy remains challenging,” the authors noted.
“A well-established mechanism for arrhythmia is the presence of myocardial fibrosis that predisposes to re-entrant circuits,” Dawson et al wrote. Some studies (Perez et al, J Am Coll Cardio 2011;57:184-94 and Hlatky et al, Circulation 2009;119:2408-16) have found that “LGE-CMR is able to detect in vivo replacement fibrosis,” they added.
In the study, published in the March 2013 issue of the Journal of the American College of Cardiology: Imaging (JACC), Dawson et al hypothesised: “If myocardial fibrosis is to be a strong predictor of malignant ventricular arrhythmia and not a simple bystander at the end-stage of disease processes, its predictive value should extend to all patients with myocardial fibrosis, independent of their left ventricular ejection fraction (LVEF) whereas the absence of fibrosis should indicate a population with a better outcome.”
In the study, 373 consecutive patients with sustained ventricular tachycardia (204) or non-sustained ventricular tachycardia (169) were enrolled between 1999 and 2009 at a single centre. They were prospectively followed-up for a median of 2.6 years for any cardiac events. The endpoint was a composite of cardiac death, cardiac arrest, new episode of sustained ventricular tachycardia, or appropriate implantable cardioverter-defibrillator discharge.
The researchers found that fibrosis was present in 38% of ventricular tachycardia patients and 27% of non-sustained ventricular tachycardia patients. Coronary artery disease, heart failure and diabetes were significantly higher in the fibrosis group. Fibrosis was also more frequent in men vs. women (42% vs. 17%). All the study population showed a mean LVEF 60 ± 13%. In the sustained ventricular tachycardia group, both left ventricular fibrosis and severely impaired systolic function (LVEF <35%) were significant independent predictors in a multivariative model. In the non-sustained ventricular tachycardia group, fibrosis was the only independent predictor of the endpoint.
The authors commented: “These findings suggest that assessment of myocardial fibrosis could be complementary to measurement of LVEF for risk stratification and could bring refinements to the current criteria for prescription of ICD as well as identify other high risk groups that did not previously qualify.”
Daniel C Lee and Jeffrey J Goldberger (Division of Cardiology, Department of Medicine, Feinberg School of Medicine, North western University, Chicago, USA) wrote in an accompanying editorial: “This study is the first to enrol patients prospectively on the basis of the presenting diagnosis of ventricular tachycardia, enabling a unique assessment of the utility of LGE-CMR in this patient population.” However, the authors still question if this technique should guide ICD implantation; they suggested that LGE-CMR will need to be tested in a randomised clinical trial.