Myocardial tissue characterization by cardiac magnetic resonance imaging using T1 mapping predicts ventricular arrhythmia in ischemic and non-ischemic cardiomyopathy patients with implantable cardioverter-defibrillators

BACKGROUND: Diffuse myocardial fibrosis may provide a substrate for the initiation and maintenance of ventricular arrhythmia. T1 mapping overcomes the limitations of the conventional delayed contrast-enhanced cardiac magnetic resonance (CE-CMR) imaging technique by allowing quantification of diffuse fibrosis.

OBJECTIVE: The purpose of this study was to assess whether myocardial tissue characterization using T1 mapping would predict ventricular arrhythmia in ischemic and non-ischemic cardiomyopathies.

METHODS: This was a prospective longitudinal study of consecutive patients receiving implantable cardioverter-defibrillators in a tertiary cardiac center. Participants underwent CMR myocardial tissue characterization using T1 mapping and conventional CE-CMR scar assessment before device implantation. The primary end point was an appropriate implantable cardioverter-defibrillator therapy or documented sustained ventricular arrhythmia.

RESULTS: One hundred thirty patients (71 ischemic and 59 non-ischemic) were included with a mean follow-up period of 430 ± 185 days (median 425 days; interquartile range 293 days). At follow-up, 23 patients (18%) experienced the primary end point. In multivariable-adjusted analyses, the following factors showed a significant association with the primary end point: secondary prevention (hazard ratio [HR] 1.70; 95% confidence interval [95% CI] 1.01-1.91), noncontrast T1(_native) for every 10-ms increment in value (HR 1.10; CI 1.04-1.16; 90-ms difference between the end point-positive and end point-negative groups), and Grayzone(_2sd-3sd) for every 1% left ventricular increment in value (HR 1.36; CI 1.15-1.61; 4% difference between the end point-positive and end point-negative groups). Other CE-CMR indices including Scar(_2sd), Scar(_FWHM), and Grayzone(_2sd-FWHM) were also significantly, even though less strongly, associated with the primary end point as compared with Grayzone(_2sd-3sd).

CONCLUSION: Quantitative myocardial tissue assessment using T1 mapping is an independent predictor of ventricular arrhythmia in both ischemic and non-ischemic cardiomyopathies.