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While sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is due to arrhythmias, the guidelines for prediction of SCD are based solely on non-electrophysiological methods. This study aims to stimulate thinking about whether the interests of patients with HCM are better served by using current, ‘risk factor’, methods of prediction or by further development of electrophysiological methods to determine arrhythmic risk. Five published predictive studies of SCD in HCM, which contain sufficient data to permit analysis, were analysed to compute receiver operating characteristics together with their confidence bounds to compare their formal prediction either by bootstrapping or Monte Carlo analysis. Four are based on clinical risk factors, one with additional MRI analysis, and were regarded as exemplars of the risk factor approach. The other used an electrophysiological method and directly compared this method to risk factors in the same patients. Prediction methods that use conventional clinical risk factors and MRI have low predictive capacities that will only detect 50–60% of patients at risk with a 15–30% false positive rate [area under the curve (AUC) = ∼0.7], while the electrophysiological method detects 90% of events with a 20% false positive rate (AUC = ∼0.89). Given improved understanding of complex arrhythmogenesis, arrhythmic SCD is likely to be more accurately predictable using electrophysiologically based approaches as opposed to current guidelines and should drive further development of electrophysiologically based methods.

Arrhythmia-mediated cardiomyopathy (AMC) is an essential clinical situation which is commonly underdiagnosed. Successful arrhythmia control leads to improvement in health-related quality of life (HRQoL) and heart failure (HF) symptoms in patients with structural heart disease (SHD).The aim of the study was to evaluate the impact of catheter ablation (CA) of persistent arrhythmia on HRQoL, biochemical and clinical parameters HF in patients with SHD and AMC.Patients with SHD, on optimal medical treatment, with persistent arrhythmia and strong suspicion of AMC, scheduled for CA were prospectively enrolled. Study procedures included: HRQoL measurement (Minnesota Living With Heart Failure Questionnaire [MLHFQ] and EuroQol Research Foundation [EQ-5D-3L] questionnaire), biomarkers (N-terminal pro-B-type natriuretic peptide [NT-proBNP], troponin T [TnT], matrix metaloproteinase-9 [MMP-9], soluble suppression of tumorigenesis-2 [sST2], tissue inhibitor of matrix metalloproteinase-1 [TIMP-1]), transthoracic echocardiography and clinical assessment.At 6 months, 30/35 (86%) patients were free of persistent arrhythmia. Patients who underwent successful CA had a significant improvement in HRQoL: MLHFQ (median [interquartile range, IQR], -22 [-28;-11]; P0.001), EQ5D-3L Score (mean [standard deviation], 21.8 (16.8); P0.001); EQ5D-3L index (median [IQR], 0.09 (0.05;0.18); p0.001). A significant decrease in injury biomarkers: NT-proBNP (median [IQR], -414 [-1397;-318] pg/ml; P0.001), TnT (median [IQR], -2.27 (-8.52;0.55) ng/ml; P0.01) but not fibrosis biomarkers (median [IQR], sST2: 2.20 [-5.4;4.3] ng/ml; P = 0.741, MMP-9: 34 [-376;283] ng/ml; P = 0.881, TIMP-1: 11.1 [-17.1;31.9] ng/ml; P = 0.215) was observed. There was a significant increase of left ventricular ejection fraction (LVEF) (mean [SD], 9.8 [5.9]; P0.01).Successful CA significantly improved clinical status, LVEF and HRQoL of patients with SHD and AMC.

The aim of the study was to systematically review evidence on the effectiveness and safety of oral mexiletine administered in monotherapy or in combination with other antiarrhythmic drugs for recurrent ventricular arrhythmia (ventricular tachycardia/ventricular fibrillation, VT/VF) in adult patients with structural heart disease (SHD) and implantable cardioverter defibrillators (ICDs). We systematically searched MEDLINE, Embase, and CENTRAL databases from inception to 27 August 2021 for prospective and retrospective studies investigating mexiletine in the target population. The main outcome was the reduction of ICD therapy. The main safety outcome was the presence of any serious adverse events (SAEs) leading to mexiletine discontinuation. Study quality was assessed using the Cochrane risk of bias tool or the Newcastle–Ottawa scale. Four studies comprising 86 mexiletine recipients were included in the review. We also obtained individual data of 50 patients from two studies. Ischaemic cardiomyopathy (ICM) was present in 86% of patients. The quality of included studies was moderate/low. A narrative review was undertaken as studies varied widely in terms of study population and treatment. Across studies, mexiletine treatment (with or without amiodarone) seemed to consistently reduce the number of ICD therapies especially in a population where catheter ablation (CA) was unsuccessful or contraindicated. In ICM patients deemed eligible for CA, mexiletine seemed to be inferior to CA. Mexiletine was discontinued in 14% of cases, mainly for gastrointestinal or neurological SAE. Mexiletine seems to be an option for the long-term treatment of recurrent VT/VF in adult patients with SHD, especially ICM, and ICD in whom CA was unsuccessful or not suitable.

To conduct a systematic review and meta-analysis to compare the effectiveness and safety of cryoballoon ablation of atrial fibrillation (AF) performed using a single freeze strategy in comparison to an empiric double (‘bonus’) freeze strategy. We systematically searched MEDLINE, EMBASE, and CENTRAL databases from inception to 12 July 2020, for prospective and retrospective studies of patients undergoing cryoballoon for paroxysmal or persistent AF comparing a single vs. bonus freeze strategy. The main outcome was atrial arrhythmia-free survival and eligible studies required at least 12 months of follow-up; the primary safety outcome was a composite of all complications. Study quality was assessed using the Cochrane risk of bias tool and the Newcastle–Ottawa Scale. Thirteen studies (3 randomized controlled trials and 10 observational studies) comprising 3163 patients were eligible for inclusion (64% males, 71.5% paroxysmal AF, mean CHA2DS2-VASc score 1.3 ± 0.9). There was no significant difference in pooled effectiveness between single freeze strategy compared to double freeze strategy [relative risk (RR) 1.03; 95% confidence interval (CI): 0.98–1.07; I2 = 0%]. Single freeze procedures were associated with a significantly lower adverse event rate (RR 0.72; 95% CI: 0.53–0.98; I2 = 0%) and shorter average procedure time (90 ± 27 min vs. 121 ± 36 min, P