Catheter-ablation of ventricular tachycardia in patients with coronary artery disease: influence of the endocardial substrate size on clinical outcome

Ablation of symptomatic ventricular tachycardia (VT) in patients with coronary artery disease is frequently performed using the three dimensional mapping system CARTO. In the amplitude map, bipolar potentials of <1.5 mV are considered abnormal and represent damaged myocardium due to previous infarction. This pathological electrical area can be arrhythmogenic, serving as the substrate for reentrant VT. The purpose of this study was to correlate the size of the endocardial substrate with the success of VT catheter ablation. Included in this retrospective analysis were 69 consecutive patients with coronary artery disease who underwent ablation for symptomatic clinical VT using CARTO. The voltage maps were analyzed and the area with abnormal bipolar electrograms (<1.5 mV) was determined using geometric approximation models. The area of abnormal electrograms was divided into three sizes: small (≤15 cm²; 11 patients), medium (16–99 cm²; 50 patients), and large (≥100 cm²; 8 patients). Patient characteristics were not different between the three substrate groups in regard to age, tachycardia cycle length, or number of radiofrequency applications, however differed significantly between the small, medium and large group in regard to left ventricular ejection fraction (44 ± 12% vs. 32 ± 9% vs. 21 ± 7%, respectively; P = 0.001). Overall, there was a significant correlation between myocardial infarction locations and endocardial substrate sizes (P = 0.031), such that 73% of small substrates were found after inferior myocardial infarctions, and 100% of large substrates after anterior and multiple myocardial infarctions (P = 0.003). After ablation, inducibility of ventricular arrhythmias was more rare in patients with small substrates compared to patients with medium or large substrates (small substrates: 9%, medium and large substrates: 43%, P = 0.043). Although during follow-up of 25 ± 17 months (1 day to 72 months) there was no significant difference between endocardial substrate sizes in regard to recurrence rates (small: 27%, medium: 38%, large: 50%, P = 0.588), patients with a small substrate did not have fast VT or ventricular fibrillation (VF), in contrast to 30% and 38% of patients with medium and large substrates, respectively. We conclude that in patients with coronary artery disease a small area of low amplitude bipolar potentials (≤15 cm²) was seen more often after inferior myocardial infarction than after anterior and multiple infarctions. After ablation, patients with small substrates were rarely inducible and showed a more benign course during follow-up (trend towards fewer arrhythmia recurrences and no fast VT or VF). As a result smaller arrhythmogenic substrates appear to be better amenable to catheter ablation than larger substrates.     

Videofluorography and pulsed fluoroscopy using a 512 X 512-pixel digital image system

The combination of videofluorography and pulsed fluoroscopy using an analog videodisc system has previously been investigated with regard to image quality and potential for dose reduction. The authors found that the system could be improved still further by replacing the analog disc with a 512 X 512-pixel digital image system, thereby increasing fluoroscopic image quality and permitting stored images to be recorded with a multiformat camera. The pulsed method is compared with low-dose-rate fluoroscopy, in which a continuous image is obtained at 1/4 of the normal rate. Whereas image quality using a low dose rate was inadequate for any useful purpose, pulsed fluoroscopy was sufficient for all but the most critical stages of the examination.     

Protective effect of Sida cordata leaf extract against CCl4 induced acute liver toxicity in rats

ObjectiveTo investigate the hepatoprotective potential of Sida cordata (Malvaceae) (S. cordata) in experimental rats to validate its traditional claim.MethodsWister albino rats were divided into 6 groups: Group I served as control; Group II served as hepatotoxic (CCl₄ treated) group; Group III, IV and V served as (100, 200 and 400 mg/kg b.w.) S. cordata leaf extract (SCLE) treated groups; Group VI served as positive control (Silymarin) treated group. Liver marker enzymes serum glutamate oxyloacetic transaminase, serum glutamic pyruvic transaminase, pancreatic enzymatic antioxidants superoxide dismutase (SOD), lipid peroxidation, catalase (CAT), reduced glutathione (GSH) were measured and compared along with histopathological studies.ResultsObtained results show that the treatment with SCLE significantly (P<0.05-<0.001) and dose-dependently reduced CCl₄ induced elevated serum level of hepatic enzymes. Furthermore, SCLE significantly (up to P<0.001) reduced the lipid peroxidation in the liver tissue and restored activities of defence antioxidant enzymes GSH, SOD and CAT towards normal levels, which was confirmed by the histopathological studies.ConclusionsThe results of this study strongly indicate the protective effect of SCLE against CCl₄ induced acute liver toxicity in rats and thereby scientifically support its traditional use.     

Temporal validation of the Australian estimated post-transplant survival score

Aims

The Australian estimated post-transplant survival (EPTS-AU) prediction score was developed by re-fitting the United States of America EPTS, without diabetes, to the Australian and New Zealand kidney transplant population over 2002–2013. The EPTS-AU score incorporates age, previous transplantation and time on dialysis. Diabetes was excluded from the score, as this was not previously recorded in the Australian allocation system. In May 2021, the EPTS-AU prediction score was incorporated into the Australian kidney allocation algorithm to optimize utility for recipients (maximized benefit). We aimed to temporally validate the EPTS-AU prediction score to ensure it can be used for this purpose.

Methods

Using the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry, we included adult recipients of deceased donor kidney-only transplants between 2014 and 2021. We constructed Cox models for patient survival. We assessed validation using measures of model fit (Akaike information criterion and misspecification), discrimination (Harrell's C statistic and Kaplan–Meier curves), and calibration (observed vs. predicted survival).

Results

Six thousand four hundred and two recipients were included in the analysis. The EPTS-AU had moderate discrimination with a C statistic of 0.69 (95% CI 0.67, 0.71), and clear delineation between Kaplan–Meier's survival curves of EPTS-AU. The EPTS was well calibrated with the predicted survivals equating with the observed survival outcomes for all prognostic groups.

Conclusions

The EPTS-AU performs reasonably well in choosing between recipients (discrimination) and to predict a recipient's survival (calibration). Reassuringly, the score is functioning as intended to predict post-transplant survival for recipients as part of the national allocation algorithm.