Catheter Ablation of Idiopathic Ventricular Arrhythmias.

Ventricular arrhythmias (VA) are observed in the setting of structural heart disease. However, in a proportion of patients presenting with VT, the routine diagnostic modalities fail to demonstrate overt myocardial abnormality. These arrhythmias have been called idiopathic VAs. They consist of various subtypes that have been defined by their anatomic location of origin within the heart and/or their underlying mechanism. While the majority of patients are asymptomatic, some experience debilitating symptoms and may develop reversible ventricular dysfunction. Catheter ablation has been traditionally reserved for patients with incapacitating symptoms or progressive ventricular dysfunction. However, as many patients are young, and catheter ablation can be curative in >90% of cases with a low risk (<1%) of serious complications, it is increasingly being offered as a first-line treatment in symptomatic patients. The approach to arrhythmia mapping is guided by the 12-lead electrocardiograph (ECG) morphology of the ventricular tachycardia (VT). Use of three dimensional (3D) electroanatomic mapping systems and intra-cardiac echocardiography are helpful in localising sites for successful ablation.

mHealth in Cardiovascular Health Care.

Mobile health (mHealth) has been defined as medical and public health practice supported by mobile devices, such as mobile phones, patient monitoring devices and personal digital assistants. Cardiovascular mHealth is, arguably, leading the mHealth space, through innovation, research and implementation, and especially in the areas of prevention, cardiac rehabilitation and education. mHealth includes simple strategies, such as the use of short message service (SMS) or text messages in successful short-term smoking-cessation, weight loss and diabetes management programs. The recent Australian Tobacco, Exercise and Diet Messages (TEXT ME) randomised clinical trial addressed multiple cardiovascular risk factors. mHealth can also involve more complex strategies, such as smart phone applications (apps), global positioning systems (GPS) and Bluetooth technologies. Although many apps could be considered suitable for primary prevention, they are largely unregulated and most are not evidence-based. Some have been well-developed, such as the Food Switch app and an iPhone electrocardiogram (ECG) system. The "explosion" of apps has driven initiatives such as the Mobile Applications Rating Scale (MARS). More recently, the use of sensors to monitor and provide feedback to patients and healthcare providers is being explored. With almost two billion people currently owning a Smartphone, and 50% of adults (globally) predicted to own one by 2018, mHealth provides the prospect of delivering efficient, affordable healthcare services to widespread populations both locally and globally. In particular, it has the potential to reduce socioeconomic disparity and alleviate the burden of cardiovascular disease. There is now a need to rethink traditional health service structures and bioengineering capacity, to ensure mHealth systems are also safe, secure and robust.

Catheter ablation versus medical therapy for treatment of ventricular tachycardia associated with structural heart disease: Systematic review and meta-analysis of randomized controlled trials and comparison with observational studies.

BACKGROUND: Catheter ablation (CA) is an established therapeutic modality for ventricular tachycardia (VT). OBJECTIVE: We compared the clinical outcomes of CA for VT vs medical therapy from all previously performed randomized controlled trials (RCTs) and compared these to contemporary observational studies. METHODS: A comprehensive database search through to August 2018 identified 8 eligible studies enrolling 797 patients. RESULTS: In RCTs, VT recurrence and electrical VT storm were significantly reduced in the CA group vs medical therapy group (relative risk [RR] 0.78, 95% confidence interval [CI] 0.64-0.95, P = .01; RR 0.70, 95% CI 0.51-0.94, P = .02, respectively) at a mean follow-up of 22 months. All-cause or cardiac-specific mortality did not differ significantly (RR 0.92, 95% CI 0.67-1.27, P = .62; RR 0.82, 95% CI 0.54-1.26, P = .37, respectively). In 4 observational studies, including 3065 patients with a mean follow-up of 18.2 months, VT recurrence and mortality were significantly lower as compared to the RCTs (28.6% vs 39%, P < .001; 13.2% vs 18%, P = .01, respectively) despite greater incidence of electrical storm (33.2% vs 17%, P < .001), higher prevalence of nonischemic substrate (46.4% vs 3.6%, P < .001), and lower rate of implanted ICDs (68% vs 94.7%, P < .001). CONCLUSION: Meta-analysis of RCT data shows that CA is superior to medical therapy for predominantly postinfarct, scar-related VT in terms of VT recurrence and electrical VT storm, with no reduction in mortality. Real-world observational studies also demonstrate significant reduction in VT recurrence and mortality, despite a sicker cohort, demonstrating replicability and translation of RCT data in the real world.

Role of Contact Force Sensing in Catheter Ablation of Cardiac Arrhythmias: Evolution or History Repeating Itself?

Adequate catheter-tissue contact facilitates efficient heat energy transfer to target tissue. Tissue contact is thus critical to achieving lesion transmurality and success of radiofrequency (RF) ablation procedures, a fact recognized more than 2 decades ago. The availability of real-time contact force (CF)-sensing catheters has reinvigorated the field of ablation biophysics and optimized lesion formation. The ability to measure and display CF came with the promise of dramatic improvement in safety and efficacy; however, CF quality was noted to have just as important an influence on lesion formation as absolute CF quantity. Multiple other factors have emerged as key elements influencing effective lesion formation, including catheter stability, lesion contiguity and continuity, lesion density, contact homogeneity across a line of ablation, spatiotemporal dynamics of contact governed by cardiac and respiratory motion, contact directionality, and anatomic wall thickness, in addition to traditional ablation indices of power and RF duration. There is greater appreciation of surrogate markers as a guide to lesion formation, such as impedance fall, loss of pace capture, and change in unipolar electrogram morphology. In contrast, other surrogates such as tactile feedback, catheter motion, and electrogram amplitude are notably poor predictors of actual contact and lesion formation. This review aims to contextualize the role of CF sensing in lesion formation with respect of the fundamental principles of biophysics of RF ablation and summarize the state-of-the-art evidence behind the role of CF in optimizing lesion formation.