Substrate characteristics and ablation outcome of left atrial tachycardia in rheumatic mitral valve disease

High density mapping of complex atrial tachycardia in patients after cardiac surgery

To provide an overview of the current application of high-density mapping (HDM) in the mechanism of complex atrial tachycardias (ATs). Complex ATs are frequently scar-related, after history of previous cardiac surgery and large scars. These scar-related ATs are difficult to manage medically and frequently recur after electrical cardioversion. HDM technologies have enabled rigorous elucidation of AT mechanisms in patients post cardiac surgery. This article showed the application of HDM technology in complex ATs from the mechanisms of complex ATs, the development of HDM technology, and the identification of scars or critical isthmus from HDM. HDM-guided approach is highly effective for identifying the ATs mechanism and critical isthmus.

Management of atrial fibrillation in rheumatic heart disease

Rheumatic heart disease (RHD) is the underlying cause of a significant proportion of atrial fibrillation (AF) in the low- and middle-income countries, while nonvalvular AF is the most common cause of AF in high-income countries. RHD is also common among African Americans, migrants, and the indigenous population of high-income countries. The onset of AF in RHD patients is a clinical marker of worse outcomes and is associated with significant morbidity and mortality. Despite RHD being a major cause of morbidity and mortality in the young in many parts of the world, it is often neglected by policymakers, the media, and even the medical fraternity. Stroke risk assessment using various risk scores has not been systematically evaluated in rheumatic AF patients. Rate control may not be ideal for symptom control in rheumatic AF patients considering the young age and an active lifestyle. There is limited information regarding the nonpharmacological management of rheumatic AF. The current management guidelines based on nonvalvular AF do not apply to rheumatic AF patients who are often younger, are women, and have fewer comorbidities. This review critically looks at specific areas such as stroke prevention with reference to direct oral anticoagulants, cardioversion, rate and rhythm control strategies, and the role of nonpharmacological methods in rheumatic AF management. Future recommendations must be cognizant of local health care systems and resourcing considering the geographic distribution of the disease.

Catheter Ablation of Left Atrial Posterior Wall Tachycardia Guided by Electroanatomic Mapping in a Young Patient

Focal atrial tachycardias (ATs) arising from the left atrium (LA) most commonly originate from the ostium of the pulmonary vein, the superior mitral annulus, the body of the coronary sinus, the LA septum, and the LA appendage. Focal ATs originating from the posterior wall of the LA are extremely rare. A 34-year-old male patient presented to the cardiology outpatient clinic complaining of palpitation. Electrocardiography showed a tachycardia at a ventricular rate of 150 bpm and a narrow QRS complex. Therefore, an electrophysiological study was performed, which was consistent with an AT. The patient underwent an electrophysiological study in tachycardias with narrow QRS complexes. The diagnostic electrophysiological findings were consistent with an AT. The AT cycle length was found to be 405 ms with variability in the ventriculoatrial interval. Simultaneous LA anatomical and activation mapping was performed during the AT using a 3D electroanatomic mapping system (CARTO) and a quadripolar unidirectional irrigated tip catheter. The activation mapping revealed that the earliest endocardial activation site was at the posterior wall of the LA, where the local electrogram was 72 ms and 35 ms before the coronary sinus reference and the P-wave onset, respectively. The activation mapping also showed centrifugal spreading and mid-diastolic, fractionated signals on the posterior wall. Radiofrequency ablation was successfully performed with 30-watt power at the site of the earliest atrial activation, with a fractionated electrogram terminating the tachycardia. LA posterior ATs are a rare form of AT. The electroanatomic mapping method enables the accurate localization of the LA focal tachycardia, and a high success rate is achieved with ablation therapy.

Ablation of atrial tachycardia in the setting of prior mitral valve surgery

BACKGROUND

Data regarding catheter ablation of post-surgical atrial tachycardia occurring after mitral valve surgery are scarce. Through a search of the literature, this study aimed to assess the feasibility of catheter ablation and the characteristics of atrial arrhythmias ablated in these patients.

METHODS

Studies assessing the main procedure parameters and the electrophysiologic findings of the investigated atrial tachycardia were selected. The electrophysiologic mechanism (focal vs. re-entrant arrhythmias), site of arrhythmia origin (left atrium vs. right atrium) and their anatomic correlation with specific surgical access and/or prior Cox-Maze IV procedure were all addressed.

RESULTS

Eleven studies including 206 patients undergoing catheter ablation of 297 post-surgical arrhythmia morphologies occurring after mitral valve surgery were considered. Major complications were observed in 2 patients only (0.9%). Restoration of sinus rhythm was achieved in 96% of patients. Macro-reentrant arrhythmia was mostly observed (90.4%) with a non-negligible proportion of focal arrhythmia (9.6%). Left-sided arrhythmia was common (54.4%,) but cavotricuspid isthmus-dependent arrhythmia was frequently reported (33%). Although specific atriotomies showed trends towards peculiar locations of the investigated arrhythmia, Cox-Maze IV procedure was the only independent predictor for left-sided arrhythmia (OR=17.3; 95% CI 7.2-41.2; P<0.0001).

CONCLUSIONS

Catheter ablation of post-surgical arrhythmia occurring after mitral valve surgery is feasible, and, in this setting, the vast majority of the arrhythmia morphologies are based on macro-reentry and in about one third of cases show cavotricuspid isthmus-dependent arrhythmia. Prior Cox-Maze-IV associated with mitral valve surgery is an independent predictor of left-sided arrhythmia possibly due to non-transmural surgical lesions.