Objectives: In areas of SARS-CoV-2 outbreak worldwide mean air pollutants concentrations vastly exceed the maximum limits. Chronic exposure to air pollutants have been associated with lung ACE-2 overexpression which is known to be the main receptor for SARS-CoV-2. The aim of this study was to analyse the relationship between air pollutants concentration (PM 2.5 and NO2) and COVID-19 outbreak, in terms of transmission, number of patients, severity of presentation and number of deaths. Methods: COVID-19 cases, ICU admissions and mortality rate were correlated with severity of air pollution in the Italian regions. Results: The highest number of COVID-19 cases were recorded in the most polluted regions with patients presenting with more severe forms of the disease requiring ICU admission. In these regions, mortality was two-fold higher than the other regions. Conclusions: From the data available we propose a "double-hit hypothesis": chronic exposure to PM 2.5 causes alveolar ACE-2 receptor overexpression. This may increase viral load in patients exposed to pollutants in turn depleting ACE-2 receptors and impairing host defences. High atmospheric NO2 may provide a second hit causing a severe form of SARS-CoV-2 in ACE-2 depleted lungs resulting in a worse outcome.

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Aims Pulsed field ablation (PFA), a non-thermal ablative modality, may show different effects on the myocardial tissue compared to thermal ablation. Thus, this study aimed to compare the left atrial (LA) structural and mechanical characteristics after PFA vs. thermal ablation. Methods and results Cardiac magnetic resonance was performed pre-ablation, acutely (<3 h), and 3 months post-ablation in 41 patients with paroxysmal atrial fibrillation (AF) undergoing pulmonary vein (PV) isolation with PFA (n = 18) or thermal ablation (n = 23, 16 radiofrequency ablations, 7 cryoablations). Late gadolinium enhancement (LGE), T2-weighted, and cine images were analysed. In the acute stage, LGE volume was 60% larger after PFA vs. thermal ablation (P < 0.001), and oedema on T2 imaging was 20% smaller (P = 0.002). Tissue changes were more homogeneous after PFA than after thermal ablation, with no sign of microvascular damage or intramural haemorrhage. In the chronic stage, the majority of acute LGE had disappeared after PFA, whereas most LGE persisted after thermal ablation. The maximum strain on PV antra, the LA expansion index, and LA active emptying fraction declined acutely after both PFA and thermal ablation but recovered at the chronic stage only with PFA. Conclusion Pulsed field ablation induces large acute LGE without microvascular damage or intramural haemorrhage. Most LGE lesions disappear in the chronic stage, suggesting a specific reparative process involving less chronic fibrosis. This process may contribute to a preserved tissue compliance and LA reservoir and booster pump functions.

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Multiple-loop ATs are complex, frequently including anatomic circuits. They have specific characteristics determined by the combination of AMAT and non-AMAT.

BackgroundFat deposition (FD) is part of the healing process after myocardial infarction. The characteristics of FD and its impact on the outcome in patients undergoing ventricular tachycardia (VT) ablation have not been thoroughly studied.Methods and ResultsWe studied consecutive patients undergoing post–myocardial infarction VT ablation with pre‐procedural cardiac computed tomography. FD was defined as intra‐myocardial attenuation ≤ −30 HU on computed tomography. Clinical, anatomical, and post‐procedural outcome was assessed in the overall population. Electrophysiological characteristics were assessed is a subgroup of patients with high‐density electro‐anatomical maps. Sixty‐nine patients were included (66±12 years). FD was detected in 44 (64%) patients. The presence of FD related to scar age (odds ratio [OR]: 1.14 per year; P=0.001) and scar extent (OR: 1.27 per segment; P=0.02). On electro‐anatomical maps, FD was characterized by lower bipolar amplitude (P<0.001) and prolonged electrogram duration (P<0.001). Although the proportion of local abnormal ventricular activation was similar (P=0.22), local abnormal ventricular activation showed lower amplitude (P<0.001) and were more delayed (P<0.001) in scars with FD. After a mean follow‐up of 26 months, patients with FD experienced a worse outcome including all‐cause mortality and VT recurrence (70% versus 28%, P log rank=0.009). On multivariate analysis, FD (hazard ratio=2.69; 95% CI, 1.12–6.46; P=0.027) and left ventricular systolic dysfunction (hazard ratio=2.57; 95% CI, 1.13–5.85; P=0.024) were independent predictors of adverse outcomes.Conclusions FD in patients with post–myocardial infarction VT undergoing catheter ablation relates to scar age and size and may be a marker of adverse outcomes including all‐cause mortality and VT recurrence.

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