Atrial fibrillation (AF) is one of the most common arrhythmias encountered in clinical practice. The pathophysiological mechanisms responsible for its development are complex, vary amongst individuals, and associated with predisposing factors. Here, we report a case of AF caused by annular constrictive pericarditis (ACP), which is extremely rare due to its unusual anatomical form. In our patient, AF was refractory to multiple antiarrhythmic medications; however, spontaneous conversion to sinus rhythm occurred when the ring encircling the right and left ventricular (RV and LV) cavities along the atrioventricular (AV) groove was severed. This suggests that atrial stretch due to atrial enlargement and increased left atrial (LA) pressure may contribute to the initiation and maintenance of AF. This report highlights the importance of the careful investigation of rare predisposing factors for AF using non-invasive diagnostic approaches and mechanical-electric feedback (MEF) as a pathophysiological mechanism for AF initiation and maintenance.

Electrical storm (ES) remains a major dilemma for clinicians, often presenting as a medical emergency associated with significant adverse outcomes. The mechanisms behind triggering ES are complex. Although the increased activation of the sympathetic nervous system was widely accepted as a major mechanism in initiating and maintaining ES, it\'s thought that the interaction between mechanical and electrical substrates may play an important role in some situations. Here we present a case of ES that was refractory to multiple antiarrhythmic medications but was stopped by interatrial shunting. We aim to highlight the importance of mechano-electric feedback (MEF) as the pathophysiological mechanisms of some types of ES and the utility of interatrial shunting as an alternative therapeutic strategy for patients with ES initially refractory to antiarrhythmic medications when there is evidence to indicate increased left ventricular filling pressure or left atrial pressure.