Introduction This document addresses the indications
This document addresses the indications for diagnostic testing, the present state of prognostic risk stratification, and the treatment strategies that have been demonstrated to improve the clinical outcome of patients with VAs. In addition, this document includes recommendations for referral of patients to centres with specialized expertise in the management of arrhythmias. Wherever appropriate, the reader is referred to other publications regarding the indications for implantable cardioverter-defibrillator (ICD) implantation [1,2], catheter ablation , inherited arrhythmia syndromes [4,5], congenital insulin receptor disease (CHD) , the use of amiodarone , and the management of patient with ICD shocks , syncope , or those nearing end of life . The consensus recommendations in this document use the standard Class I, IIa, IIb, and III classification  and the corresponding language: ‘is recommended’ for Class I consensus recommendation; ‘can be useful’ for a Class IIa consensus recommendation; ‘may be considered’ to signify a Class IIb consensus recommendation; ‘should not’ or ‘is not recommended’ for a Class III consensus recommendation (failure to provide any additional benefit and/or may be harmful). The level of evidence supporting these recommendations is defined as ‘A’, ‘B’, or ‘C’ depending on the number of populations studied, whether data are derived from randomized clinical trials, non-randomized studies, or, in the absence of large studies, the consensus opinions of experts from case studies or standards of care. Most medical interventions to prevent sudden death and to treat VAs were developed in an era when patient cohorts were small and the accepted standards to demonstrate effectiveness were lower than today. Many interventions to terminate or suppress VAs have since been used in many patients, and over time different treatment ‘patterns’ have developed in different regions of the world. The writing group has tried to accommodate reasonable variations in treatment in our recommendations, and have relied upon expert consensus for many of the recommendations put forward in this document. This is reflected by the relatively low level of evidence that supports the majority of our recommendations. Each of the recommendations was voted upon by the Writing Committee and only those where there was at least 80% agreement have been included.
Premature ventricular complexes Premature ventricular complexes (PVCs) are common both in patients with and without SHD and may be asymptomatic even for patients with high frequency of these beats. Other patients may be highly symptomatic with relatively few ectopic beats . Although a recent meta-analysis  of patients without clinically apparent SHD demonstrated an increased incidence of adverse events in patients with frequent PVCs, only one of the included studies used echocardiography to establish structural disease. The independent prognostic importance of PVCs in the presence of structural disease is not clear. Early studies demonstrated an association with increased cardiovascular mortality after MI [14,15] and with increased total mortality in patients with LV hypertrophy (LVH) . However, these studies were observational and performed in an era prior to modern management . In a study of patients with congestive heart failure [ejection fraction (EF) <35%], PVC frequency did not predict the risk of sudden death and did not provide prognostic information beyond other clinical variables .
Non-sustained ventricular tachycardia Although several different definitions have been used,  NSVT is defined as runs of beats arising from the ventricles with duration between 3 beats and 30s and with cycle length of <600ms (>100b.p.m.) . Similar to PVCs, NSVT is a relatively common finding in patients with either structurally normal or abnormal hearts[59,61,62]. Non-sustained ventricular tachycardia is found in nearly 6% of patients evaluated for palpitations . Diagnostic and therapeutic considerations for NSVT are included in several [3,60,64] recent guideline and consensus documents. In general, therapy for the underlying cardiac disease is indicated rather than for the arrhythmia itself. However, the finding of NSVT should always trigger further evaluation of the patient and a practical approach can be usefully divided into a general approach (Table 2), patients with an apparently normal heart (Table 3) and those with SHD (Table 4).