Supplementary material

MRI protocol:

The imaging protocol used has been previously published(1). In brief, the LGE-MRI studies were performed on a 1.5-Tesla MRI scanner (Signa Excite CV/i, General Electric, Milwaukee, WI) with an 8-element phased array coil placed over the chest of patients in the supine position. Images were acquired with electrocardiogram gating during breath-holds. Ten to 20 minutes after administration of 0.1-0.15 mmol/kg of intravenous gadobenate dimeglumine (MultiHance, Bracco Diagnostics, Princeton, NJ), 2-D delayed enhancement imaging was performed using an inversion-recovery sequence(2) (repetition time 6.7 ms, echo time 3.2 ms, in-plane spatial resolution 1.4´2.2 mm, slice thickness 8 mm, without gaps between slices) in the short-axis and three long-axis views of the left ventricle at matching cine-image slice locations. The inversion time (250-350 ms) was optimized to null the normal myocardium. In patients with a CIED, pre- and post-MRI interrogation and programming of the device was performed per institutional protocol(1) and the MRI was limited to the sequence of delayed enhancement and to 2.0 SARs. Scar distribution was characterized according to the American Heart Association 17-segment model.

References:

1. Horwood L, Attili A, Luba F et al. Magnetic resonance imaging in patients with cardiac implanted electronic devices: focus on contraindications to magnetic resonance imaging protocols. Europace 2017;19:812-817.

2. Simonetti OP, Kim RJ, Fieno DS et al. An improved MR imaging technique for the visualization of myocardial infarction. Radiology 2001;218:215-23.

Supplementary Table 1: Scar distribution according to the American Heart Association 17-segment model (total N=41 patients with pre-procedure MRI)

Segment # / Segment / N (%) patients with segment with late gadolinium enhancement
1 / Basal anterior / 6 (15)
2 / Basal anteroseptal / 20 (49)
3 / Basal inferoseptal / 15 (37)
4 / Basal inferior / 6 (15)
5 / Basal inferolateral / 7 (17)
6 / Basal anterolateral / 13 (32)
7 / Mid anterior / 0 (0)
8 / Mid anteroseptal / 5 (12)
9 / Mid inferoseptal / 8 (20)
10 / Mid inferior / 3 (7)
11 / Mid inferolateral / 11 (27)
12 / Mid anterolateral / 8 (20)
13 / Apical anterior / 1 (2)
14 / Apical septal / 2 (5)
15 / Apical inferior / 5 (12)
16 / Apical lateral / 5 (12)
17 / Apex / 2 (5)
Total segments / n=117

Supplementary Table 2: Comparison of Procedural Characteristics

Variables / All patients (n=96) / Imaging (n=41) / No imaging (n=55) / p-value
N clinical VTs / 1.0 (1.0-1.0) / 1.0 (1.0-2.0) / 1.0 (1.0-1.0) / 0.005
N inducible VTs / 6.0 (3.0-10.0) / 6.0 (2.0-10.0) / 6.5 (3.0-11.0) / 0.28
Non-inducible VT at procedure onset, n (%) / 2 (2) / 2 (5) / 0 (0) / 0.10
Incessant VT at procedure onset, n (%) / 3 (3) / 2 (5) / 1 (2) / 0.39
Percutaneous epicardial ablation, n (%) / 19 (20) / 7 (17) / 12 (22) / 0.56
Epicardial ablation via coronary venous system, n (%) / 23 (24) / 13 (32) / 10 (18) / 0.13
Procedure duration (hrs) / 7.8 (2.1) / 8.0 (1.8) / 7.7 (2.2) / 0.51
RF energy duration (min) / 61.5 (35.0-98.0) / 81.0 (45.0-110.0) / 51.0 (31.0-79.0) / 0.07
Fluoroscopy duration (min) / 69.1 (53.0-82.75) / 67.0 (46.2-81.0) / 69.5 (53.8-92.0) / 0.20
Post-ablation PVS deferred, n (%) / 6 (6) / 3 (7) / 3 (5) / 0.71

Continuous variables are presented as mean (standard deviation) or median (interquartile range).

Supplemental Table 3: Patient and Procedural Characteristics According to Acute Procedural Success Status

Variables / Complete success (n=39) / Non-complete success (n=57) / p-value
Age (years) / 59.3 (12.1) / 59.2 (11.5) / 0.98
Male, n (%) / 31 (79) / 49 (86) / 0.40
Ejection fraction (%) / 35.0 (27.5-45.0) / 25.0 (20.0-35.0) / 0.001
NYHA class III-IV, n (%) / 11 (28) / 14 (25) / 0.69
Recent VT storm or incessant VT, n (%) / 11 (28) / 29 (52) / 0.02
Prior VT ablation*, n (%) / 12 (31) / 31 (54) / 0.02
Atrial fibrillation, n (%) / 15 (38) / 21 (37) / 0.87
Diabetes mellitus, n (%) / 9 (23) / 16 (29) / 0.55
Hypertension, n (%) / 22 (56) / 36 (64) / 0.44
Hyperlipidemia, n (%) / 22 (56) / 33 (59) / 0.81
Renal insufficiency, n (%) / 5 (13) / 16 (28) / 0.08
Pre-ablation MRI, n (%) / 26 (67) / 15 (26) / <0.001
N clinical VTs / 1 (1-1) / 1 (1-1) / 0.66
N inducible VTs / 3 (1-7) / 8 (5-13) / <0.001
Percutaneous epicardial ablation, n (%) / 4 (10) / 15 (26) / 0.06
Epicardial ablation via coronary venous system, n (%) / 11 (28) / 12 (21) / 0.42
Procedure duration (hrs) / 7.0 (1.7) / 8.3 (2.1) / 0.003
RF energy duration (min) / 48 (31-85) / 72 (39-110) / 0.16
Fluoroscopy duration (min) / 60.9 (46.0-74.8) / 71.8 (60.0-85.0) / 0.009

Continuous variables are presented as mean (standard deviation) or median (interquartile range).

* at other institution