A Time-Efficient Alternative for Spontaneous VT Scar Assessment

A novel methodology that creates 3-dimensional (3D)-upsampled models using 2-dimensional (2D)-acquired delayed gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) images was found to be a time-efficient alternative to 3D-aquired images when assessing transmural scarring among patients with ventricular tachycardia (VT). The validation study of this methodology was published in Scientific Reports.

The study used an experimental set of 10 pigs with established myocardial infarction (MI) and 14 patients, who had been admitted to Hospital Universitario La Paz in Spain with spontaneous VT and underlying infarct-related ventricular scar. The pigs underwent percutaneous catheterization, and an MI was induced via inflation of an angioplasty balloon in the coronary artery. At 10-12 weeks, the pigs underwent 3D and 2D LGE-CMR. This novel method assesses ventricular scar using a semiautomatic approach with custom transmural criteria and creates scar maps from either 3D- or 2D-acquired images. Scar features were compared between the models. This method was also evaluated among the patients.

The patients were 85.7% men; had a median age of 69.3 (interquartile range [IQR], 65.7-73.0) years; left ventricular ejection fraction was 40.0% (IQR, 34.8%-42.3%); 92.8% had hypertension; and the median time since MI was 16 (IQR, 12.2-23.3) years.

In general, the 2D and 3D LGE-CMR images showed significant differences to the myocardial thickness (P <.001). The 3D-upsampled image was found to correlate with the 3D-acquired images for transmurality (r, 0.65), scar thickness (r, 0.72), and myocardial thickness (r, 0.67).

Among the patients, the 2D- and 3D-aquired images showed median total myocardial volumes of 205.2 and 199.5 cm³, healthy myocardial volumes of 174.4 and 174.1 cm³, heterogeneous scare volumes of 23.5 and 17.7 cm³, dense volumes of 14.3 and 8.2 cm³, and total scar volumes of 34.4 and 26.3 cm³, respectively.

Scar volumes were correlated with cycle lengths (CLs) of the VT episode for 2D- (r, 0.57; P =.04) and 3D- (r, 0.61; P =.03) acquired images. There was no correlation between CL and dense scar volumes.

Scar area quantifications were correlated with CLs of VT episode for 3D-upsampled (r, 0.69; P <.01) and 3D-acquired (r, 0.79; P <.01) images.

At 5 years, 5 patients had a VT recurrence. Patients with recurrence showed significantly smaller total scar areas in 3D model for transmurality (median, 48.5 vs 91.5 cm²; P =.004) and the upsampled transmurality model (median, 64.0 vs 83.0 cm²; P =.04), but not in the 3D- (P =.26) or 2D- (P =.27) acquired LGE-CMR. The 3D-acquired model found that 97.56% of the scar was in the 0.0-0.33 layer of the myocardial wall compared with 80.49%, as found in the 3D-upsampled model.

A limitation of this study was the differing time from gadolinium administration to imaging acquisition for 3D and 2D image capture.

The study authors concluded that this semiautomated 3D-upsampling method using 2D-acquired LGE-CMR images may be a time-saving approach to scar evaluation among patients with spontaneous VT.

“Our data provide new insights into the role of scar characterization in clinical presentation and long-term follow-up of patients with infarct-related VT episodes undergoing catheter-based ablation, especially in patients without primary [implantable cardioverter defibrillator] indication (14 out of 15 patients in this series),” the researchers noted.

Disclosure: An author declared affiliations with industry. Please refer to the original article for a full list of disclosures.

Reference

Merino-Caviedes S, Gutierrez LK, Alfonso-Almazán JM, et al. Time‑efficient three‑dimensional transmural scar assessment provides relevant substrate characterization for ventricular tachycardia features and long‑term recurrences in ischemic cardiomyopathy. Sci Rep. 2021;11(1):18722. doi:10.1038/s41598-021-97399-