Benefit of Atrial Overdrive Pacing in Patients with Sleep Apnea: A Meta-Analysis

Background: Sleep apnea is one of the most common conditions around the world. This disorder can significantly impact cardiovascular morbidity and mortality. Atrial overdrive pacing (AOP) is a treatment modality that can potentially decrease respiratory events. There is currently a lack of evidence to confirm the benefits of AOP. We aimed to assess the impact of AOP in patients with obstructive sleep apnea (OSA), central sleep apnea (CSA), and mixed type. Methods: A literature search for studies that reported the impact on apnea–hypopnea index (AHI) by cardiac implantable electronic devices with different pacing modes was conducted using MEDLINE, Embase, and Cochrane Database from inception through July 2020. Pooled standard mean difference with 95%CI was calculated using a random-effects model. Results: Fifteen studies, including thirteen randomized studies and two observational studies containing 440 patients, were identified. The standard mean difference in apnea–hypopnea index of atrial overdrive pacing demonstrated less duration of apnea/hypopnea in patients with atrial overdrive pacing (AOP) (SMD −0.29, 95%CI: −0.48, −0.10, I2 = 57%). Additional analysis was performed to assess the effect of atrial overdrive pacing in patients with or without severe sleep apnea syndrome (mean AHI < 30 defined as non-severe). There was no statistically significant difference in standardized mean in AHI in both subgroups between AOP and control groups (SMD −0.25, severe sleep apnea syndrome SMD −0.03, I2 = 0.00%). Conclusions: AOP was associated with a statistically significant reduction in AHI, but the magnitude of reduction was small. AOP may potentially be used as an adjunctive treatment with other modalities in treating patients with sleep apnea.

Temporary atrial overdrive pacing during a drug-refractory electrical storm in acute myocardial infarction

A 64-year-old man with diabetes mellitus was diagnosed with a non-ST-segment elevation myocardial infarction and was treated with stent implantation. Four days later, he developed an electrical storm (ES) that persisted despite antiarrhythmic drugs and sedation. External defibrillation was performed more than 100 times over 2 hours. After ruling out the common causes of polymorphic ventricular tachycardia, an ES was considered because of brady-dependent R-on-T phenomenon, presumably precipitated by antiarrhythmic drugs. Temporary transvenous atrial overdrive pacing allowed complete suppression of premature ventricular complexes and ventricular fibrillation.

Arrhythmia Termination During Radiofrequency Delivery Improves Outcomes after Catheter Ablation for Persistent and Long Standing Persistent Atrial Fibrillation

Background: Achieving long-term successful outcomes with catheter ablation (CA) of persistent atrial fi brillation (PsAF) remains a challenge. Multiple attempts to determine effective ablation strategies besides the pulmonary veins (PV) were made but, so far, there is no agreed standard approach and no clear consensus as to which is the best one. Among the most frequently used techniques was ablation of complex atrial fractionated electrograms (CFAE) but studies showed contradictory results. The optimal procedural endpoint also needs further refi nement. Objectives: We sought to evaluate outcomes in regard to patient characteristics and procedural termination. We also aimed to assess whether continuation of antiarrythmic therapy in the blanking period (1 to 3 months after the procedure) influences long term results. Methods: We enrolled consecutive patients with persistent and long-standing PsAF (LS-PsAF) who underwent one or more radiofrequency catheter ablations (RF CA) - pulmonary vein antral isolation (PVAI), followed by CFAE or resultant atrial tachycardia/flutter elimination, were retrospectively analyzed. Procedural objective was tachyarrhythmia (AF or resultant atrial flutters/tachycardias) termination (TT) to sinus rhythm (SR) during RF delivery. If after extensive substrate based or activation guided ablation sinus rhyhtm was not restored, conversion was performed with antiarrhythmic drugs (AAD), overdrive pacing or electrical shock. Screening for arrhythmia recurrence was performed via clinical interview and 48 hours Holter monitoring at 1,3 and 6 months and then every 6 months. Results: The cohort included 94 patients (age 54.5±11.4, 67 (71%) males, CHADSVASc 2.3±2, 11 (12%) LS-PsAF) Acute restoration of sinus rhythm (SR) was achieved in 93.4% of the cases, 43% by ablation of CFAE or resultant atrial tachycardia/fl utter(AT/AFL), 36.2% by electric cardioversion, 7.4% by chemical conversion, 3.1 % overdrive pacing, 3.7 % spontaneuous / mechanical. The long term success rate after a mean of 1.7±0.8 procedures was 59% at a mean follow-up period of 80±28 months. Freedom from AF was significantly higher when arrhythmia termination was obtained during RF delivery (p – 0.003). Short-term use of AAD in the blanking period did not lead to improved long term outcomes. Conclusions: In patients with PsAF and LS-PsAF restoration of sinus rhyhtm during RF delivery for pulmonary vein isolation, ablation of CFAE or resultant atrial tachyarrhythmia predicts long term procedural success. Further research to determine the best strategy to achieve this outcome is necessary.

Loperamide Induced Recurrent Torsades de Pointes: A Case Report

Purpose: A case of loperamide-induced recurrent torsades de pointes is reported to raise awareness of an increasingly common phenomenon that could be encountered by medical providers during the current opioid epidemic. Summary: A 40 year-old-man with a prior history of opioid abuse who presented to the emergency department after taking up to 100 tablets of loperamide 2 mg daily for 5 years to blunt opioid withdrawal symptoms and was subsequently admitted to the intensive care unit for altered mental status and hyperthermia. The patient had prolonged QTc and 2 episodes of torsades de pointes (TdP) that resulted in cardiac arrest with return of spontaneous circulation. He was managed with isoproterenol, overdrive pacing, and methylnatrexone with no other events of TdP or cardiac arrest. Conclusion: A 40-year-old male who developed torsades de pointes from loperamide overdose effectively treated with overdrive pacing, isoproterenol, and methylnatrexone.

Refractory Torsades de Pointes Due to Dofetilide Overdose

Dofetilide, a class III antiarrhythmic, is widely used in the treatment of cardiac arrhythmias. Antiarrhythmic drugs can have a long duration of action that prolongs the QT interval. This causes bradycardia that predisposes to R-on-T phenomenon subsequently leading to torsades de pointes (TdP). This necessitates constant monitoring to prevent or treat ventricular arrhythmias or bradycardia associated with cardiac medications. Although extremely rare, dofetilide overdose has been described in the literature. However, no evidence found in the current literature required prolonged intervention after the initial acute stabilization, leading to scarcity of data for treatment of ongoing dofetilide overdose. We present the case of an intentional dofetilide overdose in a 61-year-old Caucasian woman with a history of congestive heart failure, atrial fibrillation, stage IIIb chronic kidney disease, diabetes mellitus type II, hypothyroidism, morbid obesity, and hypertension that required extensive interventions for refractory TdP that lasted 4 days. Therapeutic as well as excess dosage of dofetilide can lead to TdP, which is usually controlled by decreasing the dose or terminating drug administration. If the arrhythmia is not resolved, guidelines recommend management with activated charcoal if ingestion is within 15 minutes, followed by administration of 2 g IV (intravenous) magnesium and addressing the electrolyte imbalance. However, if the arrhythmia is persistent due to ongoing dofetilide toxicity, isoproterenol is given as a bridge to overdrive pacing and dopamine is used as an alternative to isoproterenol.