RESUMO
BACKGROUND: Differentiating near-field (NF) and far-field (FF) electrograms (EGMs) is crucial in identifying critical arrhythmogenic substrate during Ventricular Tachycardia (VT) ablation. A novel algorithm annotates NF fractionated signals enabling EGM Peak Frequency (PF) determination using wavelet transformation. This study evaluated the algorithms effectiveness in identifying critical components of the VT circuit during substrate mapping. METHODS: A multicentre, international cohort undergoing VT ablation were investigated. VT activation maps were used to demarcate the isthmus zone (IZ). Offline analysis was performed to evaluate the diagnostic performance of low voltage area (LVA) PF substrate mapping. RESULTS: A total of 30 patients encompassing 198,935 EGMs were included. The IZ PF was significantly higher in sinus rhythm (SR) compared to right ventricular paced (RVp) substrate maps (234(195-294)Hz vs 197(166-220)Hz; p=0.010). Compared to LVA PF, the IZ PF was significantly higher in both SR and RVp substrate maps (AUC: 0.74 and 0.70, respectively). A LVA PF threshold of ≥200Hz was optimal in SR maps (sensitivity 69%; specificity 64%) and RVp maps (sensitivity 60%; specificity 64%) in identifying the VT isthmus. In amiodarone-treated patients (n=20), SR substrate map IZ PF was significantly lower (222(186-257)Hz vs 303(244-375)Hz, p=0.009) compared to amiodarone-naïve patients (n=10). The ≥200Hz LVA PF threshold resulted in an 80% freedom from VT with a trend towards reduced ablation lesions and radiofrequency times. CONCLUSIONS: LVA PF substrate mapping identifies critical components of the VT circuit with an optimal threshold of ≥200Hz. Isthmus PF is influenced by chronic amiodarone therapy with lower values observed during RV pacing.
RESUMO
Fibrosis is a potentially debilitating disease with high morbidity rates. It is estimated that half of all deaths that occur in the USA are attributed to fibrotic disorders. Fibrotic disorders are characterized primarily by disruption in the extracellular matrix deposition and breakdown equilibrium, leading to the accumulation of excessive amounts of extracellular matrix. Given the potentially high prevalence of fibrosis and the paucity of agents currently available for the treatment of this disease, there is an urgent need for the identification of drugs that can be utilized to treat the disease. Pentoxifylline is a methylxanthine derivative that is currently approved for the treatment of vascular diseases, in particular, claudication. Pentoxifylline has three main properties: improving the rheological properties of blood, anti-inflammatory, and antioxidative. Recently, the effectiveness of pentoxifylline in the treatment of fibrosis via attenuating and reversing fibrotic lesions has been demonstrated in several clinical trials and animal studies. As a result of the limited availability of antifibrotic agents in the long-term treatment of fibrosis that can attenuate and even reverse fibrotic lesions effectively, it would be of particular importance to consider the potential clinical utility of pentoxifylline in the treatment of fibrosis. Thus, this paper discusses the evolving roles of pentoxifylline in the treatment of different types of fibrosis.