Long-term toxicity of radiosurgery for ablation of ventricular tachycardia

Introduction

There is a rising interest in using radiosurgery to modify arrhythmogenic substrate in patients with recurrent VT. However, data on the safety are still inadequate.

Purpose

This is update of toxicity evaluation based on the compilation from our case series, NIRA-VT and STAR-VT.

Methods

Between 2014 and March 2021, 36 patients (33 male, 3 females; mean age 66±10 years) with structural heart disease (ischemic cardiopathy, dilated cardiopathy or fibroma associated scar) from two electrophysiology centers in the Czech Republic (Trinec, Prague) underwent radiosurgery for recurrent VT.

Radiosurgery was performed after at least one failed catheter ablation for VT. The critical part of the VT substrate was identified by electroanatomic mapping using a combination of voltage mapping, pace mapping, and activation mapping; and it was marked on a contrast-enhanced computer tomography study as a CTV. In NIRA-VT trial, CTV included scar based on PET/CT evaluation. Radiosurgery system with real-time motion tracking using the tip of the electrode of an indwelling defibrillator as a fiducial marker was used. A total radiation dose of 25 Gy was delivered to the ablation target in a single session during free breathing. Radiation-induced toxicity was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Only patients with follow up longer than 6 months were included in long term radiation related side effects evaluation.

Results

The mean CTV and PTV were 26±11 ml and 41±22 ml respectively. No patient exhibited acute (up to 3 months) elevation of troponin, pericardial effusion, or a decrease in left ventricular ejection fraction from baseline. Four patients developed acute mild nausea, which waned after antiemetic drugs. Long-term radiation related side effects were evaluated in 19 patients. Two patients (11%) presented radiological signs of lung fibrosis in small area in close distance from PTV. There was no significant decrease in left ventricular ejection fraction during follow up. Six patients (33%) gradually developed significant progression of known mitral regurgitation after SBRT, two (11%) of them had to undergo mitral valve replacement (grade 4 toxicity). Two cases of esophagitis (12%) were seen with one radiation toxicity related death (grade 5 toxicity) due to the unresectable esophagi-pericardial fistula (6%).

Conclusions

Our data indicate the feasibility of radiosurgery, majority of patients presented no/mild radiation related toxicity and decrease of VT burden. However, we have seen three cases of grade 4,5 toxicity. To further investigate long-term safety and efficacy of radiosuergery for VT, enrolling into a randomized prospective study is in progress.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020

Gender-specific risk of complications in catheter ablation for atrial fibrillation

Background

Catheter ablation is an established treatment modality for atrial fibrillation (AF). The risk of procedural complications is not negligible. Some studies suggested that female patients have a higher risk of complications.

Purpose

To identify gender-specific predictors of major complications (MCs) in patients undergoing catheter ablation for AF in a tertiary ablation centre.

Methods

A total of 4733 catheter ablations for AF (65% paroxysmal, 26% repeated procedures) were performed at our centre between January 2006 and August 2018. Patients (71% males) aged 60±10 years and had body mass index of 29±4 kg/m2 at the time of the procedure. Radiofrequency point-by-point ablation was employed in 96.3% procedures with the use of 3D navigation systems and facilitated by intracardiac echocardiography. Pulmonary vein isolation was mandatory; cavotricuspid isthmus and left atrial substrate ablation were performed in 22% and 38% procedures, respectively. MCs were defined as those that resulted in permanent injury, required intervention or prolonged hospitalization. Variables were assessed by uni- and multivariate analysis, two-sided α<0.05 was considered significant.

Results

A total of 160 (3.4%) MCs were detected - 60 (4.4%) in females and 100 (2.9%) in males (P=0.012). Both lower body height and the presence of bundle branch block (BBB) were associated with MCs only in females; for left bundle branch block (LBBB), the effect size was higher. On the contrary, higher left ventricular end-diastolic diameter (LVEDd) and persistent AF were associated with MCs in males (Table).

Conclusion

Females have a higher risk of MCs during catheter ablation for AF. Body height, AF type, BBB, and LVEDd may belong among gender-specific risk factors for MCs in AF ablation procedures. Whether BBB and LVEDd represent true risk factors warrants a validation in further studies.

Funding Acknowledgement

Type of funding source: None

Optimization of cardiac resynchronization therapy based on speckle tracking

OBJECTIVES

The aim of this study was to evaluate the correlation between the change in heart strains and the success rate of Cardiac Resynchronization Therapy (CRT) optimization. We further explored the benefit of speckle tracking for CRT.

METHODS

In this prospective cohort study, CRT-Ds were implanted to 60 patients. 3 months later, the response was evaluated. In the non-responders, optimization based on speckle tracking was performed. The AV interval was optimized with respect to the quality of left ventricle filling and the VV interval was optimized with respect to heart strains. After a further three months, the optimization success was evaluated.

RESULTS

Thirty-nine patients responded well to the initial CRT. The response was independent of etiology; the subsequent optimization was however more successful in dilated cardiomyopathy (DCM) (8 out of 9) than in ischemic heart disease (IHD) patients (3 out of 10 responded). The ejection fraction increase and area strain were the best predictors of NYHA improvement.

CONCLUSION

AV and VV optimization in patients who do not respond well to initial CRT seems to have better results in patients suffering from DCM. Speckle tracking (specifically A-strain) may be used to guide CRT optimization (Tab. 2, Fig. 3, Ref. 22).

Ankle-brachial index in diabetic patients - which upper cut-off value is to be used?

OBJECTIVES

In diabetic patients, there is a discrepancy in guidelines for ankle-brachial index (ABI) screening for peripheral arterial disease (PAD). While diabetes organizations suggest the value of upper limit of normal ABI to be 1.3, cardiologists recommend 1.4. Also, guidelines recommend using the higher value of ankle pressure (HAP) but multiple recent studies propose the opposite (LAP).

METHODS

In this prospective study, we performed ABI measurements in 62 diabetic patients. Results were calculated by comparing higher and lower values of ankle pressure to those of duplex ultrasound (stenosis ≥ 50 % was considered PAD). Special attention was paid to patients with high and non-measurable ABI.

RESULTS

LAP ABI appears to be a preferable method for PAD screening in diabetics. The upper cut-off value of 1.4 yielded better results with sensitivity of 93 % and negative predictive value of 91 %. No limbs with ABI between 1.3 and 1.4 with significant stenosis were found. However, using HAP for the upper cut-off captured additional PAD patients. PAD was abundant among patients with high or non-measurable ABI.

CONCLUSIONS

LAP should be used for assessing low ABI (cut-off 0.9) while HAP for detecting the abnormally high ABI. The preferable high ABI cut-off is 1.4. Condition with abnormally high or non-measurable ABI should be considered as PAD (Tab. 3, Ref. 22).

Pseudo real-time method for monitoring of the limiting anisotropy in membranes

Data acquisition and analysis of the time-resolved fluorescence anisotropy is typically a time consuming process preventing usage of this experimental method for monitoring of time-dependent phenomena. We describe a method for pseudo real-time monitoring of the limiting fluorescence anisotropy r(infinity) allowing to track changes of the membrane order occurring on the time scale of minutes. Principle and performance of the method is demonstrated in the time domain with the time-correlated single photon counting detection. DMPC liposomes stained with 1,6-diphenyl-1,3,5-hexatriene (DPH) have been used to test influence of the diffusion membrane potential on the membrane order during the temperature-induced phase transition in DMPC membranes. It has been found that the transmembrane field of the order of -70 mV increases the phase transition temperature by about 1.5 degrees C-2 degrees C. It is proposed that the full advantage of the method can be utilized with a gated detection, which besides a faster data acquisition brings additional advantage of excitation light suppression. The method can be also used for imaging.

Determination of undeformable erythrocytes in blood samples using laser light scattering

Using laser light scattering a rapid method for estimating relative counts of less deformable erythrocytes in blood samples was developed. The procedure is based on comparison of light scattering from blood cells deformed in defined shear stress and blood cells at rest, respectively.