Paroxysmal atrial fibrillation with high vs. low arrhythmia burden: atrial remodelling and ablation outcome.

AIMS: The relation between atrial tachyarrhythmia (ATA) burden in paroxysmal atrial fibrillation (AF), atrial remodelling, and efficacy of catheter ablation (CA) is unknown. We investigated whether high vs. low-burden paroxysmal AF patients have distinct clinical characteristics or electro-mechanical properties of the left atrium (LA) and whether burden impacts outcome of CA. METHODS AND RESULTS: Atrial tachyarrhythmia burden, defined as the percentage of time spent in ATA, was assessed by insertable cardiac monitors in 105 patients before and after CA. Clinical characteristics and electro-mechanical properties of LA were compared between patients with high vs. low ATA burden. Catheter ablation efficacy was assessed by reduction in ATA burden and 1-year freedom from any ATA. Median ATA burden was 2.7% (highest tertile 9.3%). Clinical characteristics and electrical properties of LA (refractoriness, conduction velocity, low voltage) did not differ between high (≥9.3%) vs. low ATA burden (<9.3%) patients. High ATA burden patients had larger LA diameter (46.5 ± 6 vs. 42.5 ± 6mm, P < 0.01), volume (93.8 ± 22 vs. 80.4 ± 21mL, P = 0.01), and lower LA reservoir and contractile strain (19.7 ± 6 vs. 24.7 ± 6%, P < 0.01; 10.3 ± 3 vs. 12.8 ± 4%, P = 0.01). Catheter ablation reduced ATA burden by 100% (100-100) in both groups (P = 1.0). Freedom from ATA after CA was equally high (83% vs. 89%, P = 0.38). CONCLUSION: Paroxysmal AF patients with high ATA burden have altered LA mechanical properties, reflected by larger size and impaired function. Despite mechanical remodelling of the atria, they are excellent responders to CA. Most likely the lack of fibrosis and/or advanced electrical remodelling explain why pulmonary veins remain the dominant trigger for AF in this patient cohort.

Tako-tsubo cardiomyopathy with left ventricular outflow tract (LVOT) obstruction: case report and review of the literature.

In this report, we describe a case of Tako-Tsubo cardiomyopathy (TTC)--also called 'apical ballooning' syndrome--in which transient left ventricular outflow tract (LVOT) obstruction and mitral regurgitation led to haemodynamic instability. Patients with hypotension should undergo urgent echocardiography to determine if LVOT obstruction is present. This complication has been described in 10-25% of all TTC patients. In patients with hypotension and moderate-to-severe LVOT obstruction, inotropic agents should not be used because they can worsen the degree of obstruction. Instead, it is suggested to use beta-blockers, which can improve haemodynamics by causing resolution of the obstruction. The fact that some patients do not survive their acute TTC event only underscores the importance of prompt recognition and targeted management of dynamic LVOT obstruction.