Oesophageal safety in voltage-guided atrial fibrillation ablation using ablation index or contact force only: a prospective comparison

AIMS

Left atrial ablation using radiofrequency (RF) is associated with endoscopically detected thermal oesophageal lesions (EDELs). The aim of this study was to compare EDEL occurrence after conventional contact force-guided (CFG) RF ablation vs. an ablation index-guided (AIG) approach in clinical routine of voltage-guided ablation (VGA). Predictors of EDEL were also assessed.

METHODS AND RESULTS

This study compared CFG (n = 100) with AIG (n = 100) in consecutive atrial fibrillation ablation procedures, in which both pulmonary vein isolation and VGA were performed. In the AIG group, AI targets were ≥500 anteriorly and ≥350-400 posteriorly. Upper endoscopy was performed after ablation.The CFG and AIG groups had comparable baseline characteristics. The EDEL occurred in 6 and 5% (P = 0.86) in the CFG and AIG groups, respectively. Category 2 lesions occurred in 4 and 2% (P = 0.68), respectively. All EDEL healed under proton pump inhibitor therapy. The AI > 520 was the only predictor of EDEL [odds ratio (OR) 3.84; P = 0.039]. The more extensive Category 2 lesions were predicted by: AI max > 520 during posterior ablation (OR 7.05; P = 0.042), application of posterior or roof lines (OR 5.19; P = 0.039), existence of cardiomyopathy (OR 4.93; P = 0.047), and CHA2DS2-VASc score (OR 1.71; P = 0.044). The only Category 2 lesion with AI max < 520 (467) occurred in a patient with low body mass index.

CONCLUSIONS

Both methods were comparable with respect to clinical complications and EDEL. In consideration of previous reconnection data and our study results regarding oesophageal safety, optimal AI target range might be between 400 and 450.

CMR assessment of right ventricular remodeling after transcatheter therapy for severe tricuspid regurgitation

Funding Acknowledgements

Type of funding sources: Private hospital(s). Main funding source(s): Helios Clinical Research Institute

Background/Introduction

Patients with severe tricuspid regurgitation (TR) are characterized from severe dilatation and negative remodeling of the right heart chambers causing functional right ventricular (RV) failure and increased mortality and morbidity. The transcatheter tricuspid edge-to-edge repair (TTVR) is a new treatment option associated with symptom improvement and reduced hospitalization. The cardiac magnetic resonance imaging (CMRI) remains the gold standard for evaluating the right ventricular morphology and function and could be a useful in assessing the RV reverse remodeling after TTVR.  The Tricuspid Regurgitation REgistry (TRuE) is an ongoing national prospective register of patients with severe TR that aims to identify morphofunctional parameters of the right heart chambers related to improve outcomes after TTVR.

Purpose

The present is a subanalysis of patients with serial CMRI examinations recruited in the ongoing prospective TRuE registry.

Methods

After excluding patients with intracardiac RV leads, seven patients (age 70 ±12 years) with completed thirty-day follow up were included in the present analysis. Retrospective gated steady state free precession cine images were acquired in the long and short-axis views covering the entirety of both ventricles. Aortic and pulmonary flow data were acquired with a flow-sensitive gradient echo sequence. Assessment of left ventricular (LV) and RV volumes was performed manually in the short-axis cine images (Circle Cardiovascular Imaging, Calgary, Alberta, Canada). The TR fraction was calculated as: ({total RV stroke volume (SV) – total pulmonary forward flow}/total RVSV) × 100. All volumes and flow measurements were indexed for body surface area and expressed in ml/m2. The ratio between the diameter of pulmonary artery (PA) and ascending aorta (AA) was used as indirect measurement of pulmonary arterial hypertension (PAH). CMRI parameters assessing TR quantification, RV morphology and function were analyzed at baseline and follow-up with Fisher´s test or paired t-test.

Results

At thirty days there was a significant reduction of the TR fraction (45% to 20%, p &lt; 0.001), RV dilatation (RV-end diastolic volume (EDV): 106 ± 12ml/m2 to 86 ± 9.4ml/m2, p = 0.002, RV- end sistolic volume (ESV):55 ± 6.5 to 43 ± 6.6ml, p = 0.003) and improvement of function (RVEF: 47 ± 3.6 to 53 ± 2.4 %, p = 0.006). On the left heart side, there was an improvement of LV filling, with increased LVEDV and LVESV and of the LVSV (36 ± 5.3 to 41 ± 3.7ml/m2, p = 0.040), causing an improvement of the cardiac index (2.2 ± 0.9 l/min/m2 to 2.9 ± 0.7 l/min/m2; p = 0.019. Furthermore, the PA/AA ratio improved significantly (0.91 ± 0.15 to 0.81 ± 0.14, p = 0.006).

Conclusion

TTVR is associated with positive reverse remodeling of the RV with reduction of dilatation, PAH and function improvement.

Glycolytic oscillations in single ischemic cardiomyocytes at near anoxia

Previous studies have shown that oscillations of the metabolism can occur in cardiomyocytes under conditions simulating ischemia/reperfusion. It is not known whether they can also occur during real ischemia with near-anoxic oxygen tension. Here, using oxygen clamp in on-chip picochambers, we exposed single resting cardiomyocytes to near anoxia (pO₂ < 0.1 mm Hg). We show that at near anoxia, the mitochondrial membrane potential (ΔΨ) was kept by the F₁F₀-ATPase reversal, using glycolytic adenosine triphosphate (ATP). In many cells, activation of current through sarcolemmal K_ATP channels (I_KATP) started after a delay with one or several oscillations (frequency of 0.044 ± 0.002 Hz). These oscillations were time correlated with oscillations of ΔΨ. Metabolic oscillations at near anoxia are driven by glycolysis because (a) they were inhibited when glycolysis was blocked, (b) they persisted in cells treated with cytoplasmic reactive oxygen species scavengers, and (c) the highest rate of ATP synthesis during an oscillation cycle was associated with the generation of reducing equivalents. Glycolytic oscillations could be initiated upon rapid, but not slow, transition to near anoxia, indicating that the speed of ATP/ADP ratio drop is a determinant of their occurrence. At enhanced oxidative stress, the rate of ATP consumption was increased as indicated by rapid I_KATP activation with large-scale oscillations. These results show that metabolic oscillations occur in cardiomyocytes at near anoxia and are driven by glycolysis and modulated by mitochondria through the rate of ATP hydrolysis, which, in turn, can be accelerated by oxidative stress.