Predicting Post-Infarct Ventricular Tachycardia by Integrating Cardiac MRI and Advanced Computational Reentrant Pathway Analysis

BACKGROUND

Implantable cardiac defibrillator (ICD) implantation can protect against sudden cardiac death (SCD) after a myocardial infarction. However, improved risk stratification for device requirement is still needed.

OBJECTIVE

To improve assessment of post-infarct ventricular electro-pathology and prediction of appropriate ICD therapy by combining late gadolinium enhancement (LGE) and advanced computational modelling.

METHODS

ADAS LV and custom-made software was used to generate 3D patient-specific ventricular models in a prospective cohort of post-infarct patients (n=40) having undergone LGE imaging pre-ICD implantation. Corridor metrics and 3D surface features were computed from LGE images. The Virtual Induction and Treatment of Arrhythmias (VITA) framework was applied to patient-specific models to comprehensively probe the vulnerability of the scar substrate to sustaining reentrant circuits. Imaging and VITA metrics, related to the numbers of induced VTs and their corresponding round trip times (RTTs), were compared with ICD therapy during follow-up.

RESULTS

Patients with an event (n=17) had a larger interface between healthy-scar and higher VITA metrics. Cox-regression demonstrated a significant independent association with an event: interface (HR 2.79; 1.44-5.44, p < .01), unique VTs (HR 1.67; CI 1.04-2.68, p = .03), mean RTT (HR 2.14; CI 1.11-4.12, p = .02), maximum RTT (HR 2.13; CI 1.19-3.81, p = .01).

CONCLUSION

Detailed quantitative analysis of LGE based scarmaps, combined with advanced computational modeling, is able to accurately predict ICD therapy and could facilitate early identification of high-risk patients in addition to LVEF.

Pulmonary vein isolation in a real-world population does not influence QTc interval

AIMS

We aimed to examine whether routine pulmonary vein isolation (PVI) induces significant ventricular repolarization changes as suggested earlier.

METHODS AND RESULTS

Five-minute electrocardiograms were recorded at hospital's admission (T-1d), 1 day after the PVI-procedure (T+1d) and at 3 months post-procedure (T+3m) from a registry of consecutive atrial fibrillation (AF) patients scheduled for routine PVI with different PVI modalities (radiofrequency, cryo-ablation, and hybrid). Only patients who were in sinus rhythm at all three recordings (n = 117) were included. QT-intervals and QT-dispersion were evaluated with custom-made software and QTc was calculated using Bazett's, Fridericia's, Framingham's, and Hodges' formulas. Both QT- and RR-intervals were significantly shorter at T+1d (399 ± 37 and 870 ± 141 ms) and T+3m (407 ± 36 and 950 ± 140 ms) compared with baseline (417 ± 36 and 1025 ± 164 ms). There was no statistically significant within-subject difference in QTc Fridericia (T-1d 416 ± 28 ms, T+1d 419 ± 33 ms, and T+3m 414 ± 25 ms) and QT-dispersion (T-1d 18 ± 12 ms, T+1d 21 ± 19 ms, and T+3m 17 ± 12 ms) between the recordings. A multiple linear regression model with age, sex, AF type, ablation technique, first/re-do ablation, and AF recurrence to predict the change in QTc at T+3m with respect to QTc at T-1d did not reach significance which indicates that the change in QTc does not differ between all subgroups (age, sex, AF type, ablation technique, first/re-do ablation, and AF recurrence).

CONCLUSION

Based on our data a routine PVI does not result in a prolongation of QTc in a real-world population. These findings, therefore, suggest that there is no need to intensify post-PVI QT-interval monitoring.

Does a well developed collateral circulation predispose to restenosis after percutaneous coronary intervention? An intravascular ultrasound study

OBJECTIVE

To evaluate whether a well developed collateral circulation predisposes to restenosis after percutaneous coronary intervention (PCI).

DESIGN

Prospective observational study.

PATIENTS AND SETTING

58 patients undergoing elective single vessel PCI in a tertiary referral interventional cardiac unit in the UK.

METHODS

Collateral flow index (CFI) was calculated as (Pw-Pv)/(Pa-Pv), where Pa, Pw, and Pv are aortic, coronary wedge, and right atrial pressures during maximum hyperaemia. Collateral supply was considered poor (CFI < 0.25) or good (CFI > or = 0.25).

MAIN OUTCOME MEASURES

In-stent restenosis six months after PCI, classified as neointimal volume > or = 25% stent volume on intravascular ultrasound (IVUS), or minimum lumen area < or = 50% stent area on IVUS, or minimum lumen diameter < or = 50% reference vessel diameter on quantitative coronary angiography.

RESULTS

Patients with good collaterals had more severe coronary stenoses at baseline (90 (11)% v 75 (16)%, p < 0.001). Restenosis rates were similar in poor and good collateral groups (35% v 43%, p = 0.76 for diameter restenosis, 27% v 45%, p = 0.34 for area restenosis, and 23% v 24%, p = 0.84 for volumetric restenosis). CFI was not correlated with diameter, area, or volumetric restenosis (r2 < 0.1 for each). By multivariate analysis, stent diameter, stent length, > 10% residual stenosis, and smoking history were predictive of restenosis.

CONCLUSION

A well developed collateral circulation does not predict an increased risk of restenosis after PCI.