Response to atrial overdrive pacing during narrow QRS tachycardia. What is the mechanism?

A 35-year old lady with no pre-excitation on surface electrocardiogram underwent EP study for recurrent palpitation and documented adenosine responsive narrow QRS tachycardia. Regular narrow QRS tachycardia was induced with critical AH delay on programmed atrial stimulation. An atrial overdrive pacing (AOD) was performed during the tachycardia (Fig: 1 & 2). What is the response to AOD and what is the mechanism of tachycardia?

A patient with atrioventricular block and ventricular tachycardia: think sarcoid!

Cardiac involvement in sarcoidosis is often difficult to diagnose, and most alarmingly can lead to sudden cardiac arrest as its first manifestation. We report the case of a 45-year-old Indian woman with an implanted permanent pacemaker for atrioventricular block, who presented with haemodynamically stable ventricular tachycardia and was found to have impaired left ventricular function. Subsequent investigations established the diagnosis of cardiac sarcoidosis. The patient was treated with prednisolone initially at 40 mg a day for 3 months. Left ventricular function improved over 3 months of treatment and there was no further recurrence of ventricular tachycardia. Screening for cardiac sarcoidosis should be considered in a patient with unexplained atrioventricular block and ventricular tachycardia, particularly if young, even in the absence of clinical findings of extracardiac sarcoidosis. Treatment of the cardiac sarcoidosis could control ventricular tachycardia and improve left ventricular function.

Prevalence of atrial high-rate episodes and the risk factors in Indian patients with cardiac implantable electronic devices: Real-world data.

BACKGROUND: In patients with cardiac implantable electronic devices (CIEDs), atrial high-rate episodes (AHREs) are associated with an increased risk of developing atrial fibrillation (AF) and thromboembolism. We report here the characteristics of "real-world" patients that may be associated with the occurrence of AHREs. METHODS: This was an observational, cross-sectional, data collection study. Data of 234 patients with dual-chamber CIEDs, who visited our clinic over a period of 3 months, were evaluated. Occurrence of AHRE was defined as atrial tachyarrhythmia with an atrial rate of ≥180 beats/min lasting for ≥5 minutes. Multivariate logistic regression analyses were performed to evaluate clinical risk factors associated with AHRE. RESULTS: The mean age of the group was 66.9 ± 9.95 years, and 25% were females. AHREs were recorded in 48 (21%) patients. Multivariate logistic regression analysis revealed that hypertension (HTN) (OR = 4.14; 95% CI: 1.74-9.85; P = .0013) and type II diabetes mellitus (T2DM) (OR = 2.09; 95% CI: 1.04-4.23; P = .0392) were significantly and independently associated with the occurrence of AHRE. CONCLUSION: This real-world data report the prevalence of and risk factors associated with AHRE occurrence in Indian patients with dual-chamber CIED. Known risk factors for AF, such as HTN and diabetes mellitus, were also associated with AHRE occurrence, thus supporting the risk prediction for AF, stroke, or thromboembolism in such patient population.