Ischemic stroke cause remains undetermined in 30% of cases, leading to a diagnosis of cryptogenic stroke. Paroxysmal atrial fibrillation (AF) is a major cause of ischemic stroke but may go undetected with short periods of ECG monitoring. The Cryptogenic Stroke and Underlying Atrial Fibrillation trial (CRYSTAL AF) demonstrated that long-term electrocardiographic monitoring with insertable cardiac monitors (ICM) is superior to conventional follow-up in detecting AF in the population with cryptogenic stroke. We evaluated the sensitivity and negative predictive value (NPV) of various external monitoring techniques within a cryptogenic stroke cohort. Simulated intermittent monitoring strategies were compared to continuous rhythm monitoring in 168 ICM patients of the CRYSTAL AF trial. Short-term monitoring included a single 24-hour, 48-hour, and 7-day Holter and 21-day and 30-day event recorders. Periodic monitoring consisted of quarterly monitoring through 24-hour, 48-hour, and 7-day Holters and monthly 24-hour Holters. For a single monitoring period, the sensitivity for AF diagnosis was lowest with a 24-hour Holter (1.3%) and highest with a 30-day event recorder (22.8%). The NPV ranged from 82.3% to 85.6% for all single external monitoring strategies. Quarterly monitoring with 24-hour Holters had a sensitivity of 3.1%, whereas quarterly 7-day monitors increased the sensitivity to 20.8%. The NPVs for repetitive periodic monitoring strategies were similar at 82.6% to 85.3%. Long-term continuous monitoring was superior in detecting AF compared to all intermittent monitoring strategies evaluated (p <0.001). Long-term continuous electrocardiographic monitoring with ICMs is significantly more effective than any of the simulated intermittent monitoring strategies for identifying AF in patients with previous cryptogenic stroke.

Ablation of atypical atrial flutter is challenging and time consuming. This case series shows that HD-VGM mapping can quickly localize and terminate an atypical flutter circuit.

Background: This study describes the use of lesion index (LSI) as a direct measure to assess the adequacy of ablation lesion formation with force-sensing catheters in ablation of paroxysmal atrial fibrillation (PAF). LSI is calculated by the formula:LSI = CF (g) ×Current (mA) ×Time (sec). Methods: Fifty consecutive patients with PAF underwent pulmonary vein (PV) isolation using a catheter dragging technique and targeting different LSI values in different anatomical areas.A force-sensing ablation catheter was used to continuously measure contact force (CF) and guide radiofrequency ablation (RF) lesion formation. Ablation lesions were delivered to achieve an LSI value of 5.0 in posterior locations, 5.5 in anterior locations and 6.0 in the region between the left atrial appendage and left superior pulmonary vein ridge. Force-time Integral (FTI) was not used to evaluate lesion formation. Results: A single center, retrospective analysis was performed with 196/198 (99%) PVs acutely isolated. The mean procedure time was 134 ± 34 mins and the mean fluoroscopy time was 7.8 ± 3.2 mins. At a mean follow up of two years, 43/50 (86%) of patients were in normal sinus rhythm with no documented recurrences of atrial fibrillation. Conclusion: LSI can be used to guide the placement of durable lesion formation with RF ablation using CF catheters in patients with PAF.

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