Antidromic AVRT with changing His activation. What is the mechanism?

We present a case of antidromic AVRT involving an atriofascicular pathway in a patient with an atretic coronary sinus os. This patient had left ventricular dysfunction with rate-related left bundle branch block aberrancy in sinus rhythm. In the electrophysiology lab, there was VA dissociation for a few beats during antidromic tachycardia. The possible mechanisms that could explain this intracardiac finding are discussed.

Does Cardiac Arrhythmia Predict Worse Outcome in Mild or Moderate Covid-19 Infection?

Covid-19 is a multisystem disease with the lungs being predominantly affected. Cardiac involvement is mostly seen as a rise in troponins, arrhythmias, and ventricular dysfunction. This study aimed to estimate the incidence of arrhythmias seen in Covid-19 infection and assess if arrhythmias predict worsening or mortality. Prospective observational study involving patients with mild to moderate Covid illness admitted in a tertiary care centre. Among the 85 patients (Mean age 45.8 + 14.1 years; 75.31% men), worsening of Covid-19 illness was seen in 29 (34.1%) patients. New onset arrhythmias were detected on Holter in 9 (10.5%) patients. Supraventricular tachycardia was seen in 7 (8.2%) patients of whom 6 showed worsening which was statistically significant (p-value-0.006). Risk factors associated with worsening on univariate analysis were male gender (OR [95%CI] = 6.93(1.49-32.31), p-value - 0.014), new onset supraventricular tachycardia (OR [95% CI] = 14.35 [1.64-125.94], p-value - 0.016) and D-dimer elevation (OR [95% CI] = 1.00(1.00-1.01), p-value - 0.02). On multivariate analysis D-dimer (OR [95% CI] = 1.00(1.00-1.01; p-value 0.046) and supraventricular arrhythmias (OR [95% CI] = 11.12 (1.22-101.14); p-value - 0.033) were independently associated with worsening. Covid-19 infection can lead to cardiac arrhythmias. The development of supraventricular tachycardia in patients with Covid-19 infection predicts higher morbidity and worsening.

Early dose of Adenosine, postRadiofrequency abLation of accessory pathwaY in determining acute procedural success (EARLY study).

INTRODUCTION: Post ablation of the accessory pathway (AP), the patient is observed in the catheterization laboratory for a variable period for resumption of pathway conduction. Aim of the study was to determine whether the administration of intravenous adenosine at 10 min after ablation of AP would have the same diagnostic accuracy as waiting for 30 min in predicting the resumption of AP conduction. METHODS: This was a prospective interventional study conducted in two centers. Post ablation of the AP, intravenous adenosine was administered at 10 min to look for dormant pathway conduction. The response was recorded as positive (presence of pathway conduction), negative (absence), or indeterminate (not able to demonstrate AV and VA block and inability to ascertain AP conduction). RESULTS: The study included 110 procedures performed in 109 patients. Adenosine administration at 10 min showed positive result in 3 cases (2.7%), negative result in 99 cases (90%) and indeterminate result in 8 cases (7.3%). Reconnection of accessory pathway at 30 min postablation was seen in 8 cases (7.3%). Of these 8 cases, 10 min adenosine administration showed positive test in 3 patients and negative test in 5 patients. Adenosine test at 10 min has a sensitivity, specificity, positive predictive value, and negative predictive value of 37.5%, 100%, 100%, and 94.9% in identifying the recurrence of accessory pathway conduction at 30 min, respectively. CONCLUSION: Absence of pathway conduction on administration of adenosine 10 min postablation does not help predict the absence of resumption of conduction thereafter.

Impact of transesophageal electrophysiological study on midterm management of pediatric tachyarrhythmias.

Background: Transesophageal electrophysiological study (TEEPS) is a minimally invasive procedure that helps in evaluating the risk of recurrence of supraventricular tachycardia based on the inducibility of the tachycardia. The purpose of this study was to evaluate the diagnostic capability, negative predictive value of noninducibility of tachycardia and safety of TEEPS among the Indian pediatric population. Methods: It is a retrospective single-center observational study of all patients who underwent TEEPS from January 01, 2014, to December 31, 2020. Results: Twenty-two TEEPS procedures were done in eighteen children with three children undergoing more than one procedure. The median duration of follow-up was 42.97 months (8.52-82.12 months). Out of the 22 procedures, four were conducted for acute tachycardia termination, two for tachycardia suppression assessment, and sixteen to assess tachycardia inducibility off medications. Tachycardia was noninducible in nine children and inducible in six children. Two children had clinical recurrence of tachycardia on follow-up. Out of these two children, one had noninducibility of tachycardia on TEEPS. The negative predictive value of TEEPS was 88.89% in this study. None of the children had any postprocedure complication. Conclusions: TEEPS is a safe procedure. It is used to assess the efficacy of medication in the suppression of arrhythmia. The noninducibility of tachycardia has a high negative predictive value and is a good indicator of nonrecurrence of clinical tachycardia on midterm follow-up.

Do the predictors of right ventricular pacing-induced cardiomyopathy add up?

OBJECTIVE: Knowledge of factors causing pacing-induced cardiomyopathy (PICM) is incomplete. We sought to estimate the incidence and predisposing factors for PICM and evaluate if the risk they portend adds up. METHODS: Single centre retrospective study where consecutive patients with preserved LVEF undergoing pacemaker (PM) implantation between 2012 and 2018 were analysed. RESULTS: A total of 749 patients (68.4 % male; mean age 59.2 ± 14.08 years) were included in the analysis. PICM developed in 74 (9.9%) patients over a median follow up of 2.2 years (IQR 1.1-3.2). Pre-implant LVEF, paced QRS duration and RV pacing burden were independent predictors of PICM. Using 90 % specificity cut-off values for LVEF and paced QRS, and the value separating lowest tertile of RV pacing from the higher tertiles, three risk factors were identified: (i) baseline LVEF < 55 %, (ii) paced QRS duration > 160 msec, and (iii) RV pacing burden > 33 %. Patients with two or more risk factors were at the highest risk (OR 11.62, 95 % CI 4.62-29.21, p-value < 0.001) for developing PICM while those with one risk factor had an intermediate risk (OR 3.89, 95 % CI 1.62-9.34, p-value 0.002) when compared to those without any risk factors. CONCLUSION: Low-normal baseline LVEF, wider paced QRS and higher RV pacing burden independently predicted the development of PICM. The presence of ≥2 factors increased the odds of PICM, twelve-fold. A narrower paced QRS, the only modifiable risk factor may help mitigate development of PICM.

Postpacing interval is shorter than tachycardia cycle length-What's the mechanism?

A 33-year-old male who underwent surgery for Tetralogy of Fallot presented with atrial flutter. Electrophysiology study revealed concealed entrainment along the mid lateral right atrium with postpacing interval shorter than the tachycardia cycle length. Ablation at this site terminated the tachycardia. The presence of shorter PPI than TCL was due to a large virtual electrode leading to downstream capture of far field tissue. This case demonstrates that sites showing PPI shorter than TCL are in a slow conducting narrow critical isthmus and hence constitute good ablation targets.

Prognostic significance of accelerated ventricular response during radiofrequency ablation of premature ventricular complexes.

BACKGROUND: Accelerated ventricular response is frequently observed during radiofrequency ablation (RFA) of premature ventricular complexes (PVCs). We hypothesized that acceleration indicates an appropriate site and adequate injury to the arrhythmogenic tissue, and sought to investigate its value in predicting the outcome. METHODS: We retrospectively analyzed RFA procedures performed for PVCs in our institution from 2011 to 2019. RESULTS: Fifty-eight patients (29 male; age 42.7 ± 15.6 years) underwent 62 RFA procedures. The most common site was the right ventricular outflow tract (67.7%). Acute success was seen in 88.7%. Accelerated ventricular response was observed in 60.0% of the successful procedures. After a median follow-up of 14.0 months (IQR: 6.0-26.6 months), 16 patients had a recurrence. Recurrence was significantly lower in the group with acceleration than in the group without acceleration (12.5% vs. 57.1%; log-rank P < 0.001). The 1-year recurrence rate was 6.5% in the acceleration group and 41.6% in the group without acceleration. On multivariable analysis the adjusted hazard ratio was 0.17 (95% CI, 0.04-0.64; Cox regression P = 0.009). The sensitivity, specificity, positive predictive, and negative predictive values of accelerated response to predict long-term success were 75.7%, 75.0%, 87.5%, and 57.2%, respectively. CONCLUSIONS: The recurrence after PVC ablation is significantly lower when an accelerated response was observed at the successful location during RFA. This can be an additional useful marker of long-term success.