In the present guidelines,1 autopsy is given a I-C recommendation to determine the cause of the unexpected death. Histology of the heart and toxicological evaluation of the blood and other fluids is a Class I recommendation. Postmortem genetic assessment is considered a Class IIa recommendation when cardiac channelopathy is suspected. However, the guidelines advise against the use of large panels of genes in SCD assessment and recommend targeted genetic study.

Cardioverter defibrillator implantation is the most effective option for both primary and secondary prevention of SCD, and its use is growing in our setting.6 Since the 2006 guidelines,2 several long-term studies have confirmed the benefits of implantable cardioverter defibrillators (ICD). Traditionally, it was considered necessary to maintain a waiting period of 40 days from the AMI event to device implantation. An interesting innovation in the approach now allows “prompt” (< 40 days) implantation when specific conditions are met, such as pre-existing LVEF dysfunction, incomplete revascularization, and the presence of nonsustained ventricular tachycardia more than 48hours after the event. This is one of the most controversial aspects of these new guidelines, as it is not based on firm evidence and there are alternative options, such as wearable defibrillator vests (Table 1).

The transvenous leads are the most vulnerable components of subcutaneous ICD. A recently developed defibrillator system with subcutaneous electrodes has proven effective in preventing SCD due to ventricular arrhythmias.7 Pending the publication of randomized studies, the initial results are promising (Table 1).

External cardioverter defibrillators attached to a wearable vest are recommended (IIb-C) for limited use in patients without an ICD indication as a bridge to cardiac transplantation, following an AMI with poor LVEF, and in conditions that can improve with time (eg, myocarditis and peripartum cardiomyopathy). Although there are no prospective studies investigating their effectiveness, registries have reported successful use of these devices in the treatment of ventricular arrhythmias.

The guidelines recommend the establishment of external defibrillators (I-B) in busy public places where there is a relatively high possibility of cardiac arrest, such as schools, sports stadiums, and public transport stations. These defibrillators may also be considered for home use (Class IIb recommendation) in families with a high risk of SCD.

Catheter ablation is considered a Class I, Level B recommendation for the treatment of electrical storm and for patients with ICD delivering recurrent shocks. It is also indicated after a first episode of ventricular tachycardia (VT) in patients with ischemic heart disease (IIa-B). Nonetheless, VT ablation is difficult and the outcome is highly operator-dependent (experience and volume of patients treated). Therefore, prompt transfer to a specialized center is recommended in patients with electrical storm.

Surgery for arrhythmias is uncommon and the procedures should be performed in experienced centers. Surgery can be considered in arrhythmias refractory to medical therapy and after failed catheter ablation, particularly if surgical revascularization is planned and the patient has a ventricular aneurysm.

Magnetic resonance imaging (MRI) is not recommended for stratifying SCD risk in patients with DCM. One innovation in this section is the use of electrophysiologic assessment for prognostic stratification of DCM (IIb-B). This practice is unusual because of the low sensitivity of the test, and the recommendation is controversial. In contrast to the previous guidelines, the update recommends (I-B) coronary angiography in stable DCM patients with an intermediate risk of coronary disease and new-onset ventricular arrhythmia. ICD implantation is recommended for patients with poor hemodynamic tolerance of ventricular arrhythmias, regardless of the LVEF (I-A), and for patients with DCM and LVEF <35% in NYHA class II or III (I-B). The previous guidelines recommended ICD implantation in DCM patients with syncope and significant left ventricular dysfunction, but in the update, management of DCM patients with syncope has been eliminated. Removal of this recommendation may generate confusion. The recommendation for an ICD in patients in NYHA class I has also disappeared.

The main therapeutic innovation in the update is the recommendation for ICD implantation (IIa-B) in patients with DCM and clinical risk factors (nonsustained VT, male sex, and LVEF <45%) after confirmation of a causative mutation in the laminin gene.

Identification and treatment of proarrhythmogenic risk factors is stressed (I-B). Amiodarone is recommended in patients with recurrent appropriate shocks despite optimal device programming (IIa-C), but should not be used in patients with asymptomatic episodes of nonsustained VT (III-A). Dronedarone and sodium channel blockers are contraindicated because of their proarrhythmic risk. The role of catheter ablation for VT in DCM patients is covered in a specific section: The recommendation for ablation in bundle branch re-entry VT is maintained (I-B), whereas ablation is limited to patients refractory to medical therapy in VT secondary to other mechanisms (IIb-C). The grading of the recommendation is lower than that of a previous consensus statement12 (IIa-B).

In patients with hypertrophic cardiomyopathy, the current update adopts the risk stratification approach of the 2014 European guidelines.13,14 Risk stratification for SCD is recommended in individuals older than 16 years (I-B) at the time of the initial evaluation and every 1 or 2 years thereafter or when there is a change in the clinical status (I-B). Avoidance of competitive sports is recommended (I-C). In contrast to the previous guidelines, the update advises against electrophysiologic evaluation for prognostic stratification (III-C). ICD implantation may be considered in secondary prevention (I-B) and in primary prevention for patients with an estimated 5-year risk of SCD >6% (IIa-B) or between 4% and 6% (IIb-B). ICD placement is also recommended (IIb-B) in patients with an estimated 5-year risk < 4% when they have other clinical features of prognostic value.

In pediatric patients, the European guideline recommendations for ICD placement have been maintained: ICD can be used in secondary prevention and in primary prevention when the patient has 2 or more of the major risk factors for SCD in children. In patients with a single risk factor, the indication for an ICD can be evaluated on an individual basis.

Some general recommendations are incorporated in this section, such as avoidance of competitive sports (I-C), beta-blocker therapy in symptomatic patients with ventricular extrasystoles or runs of nonsustained VT (I-C), and amiodarone therapy in patients who are intolerant of or have contraindications to beta blockers (IIa-C). ICD implantation is recommended in secondary prevention for patients with hemodynamically poorly tolerated arrhythmias (I-C), those with hemodynamically well-tolerated VT (IIa-C), and those with syncope. ICD placement can be considered for primary prevention in patients with risk factors (recommendation rated IIb-C vs IIa-C in the previous guidelines). Finally, catheter ablation should be considered in patients with frequent episodes of VT, with the aim of improving the symptoms or reducing the number of ICD shocks (IIa-B).

Recommendations have been established for several types of cardiomyopathies that were not present in the previous guidelines. ICD implantation should be considered in patients with cardiac amyloidosis and ventricular arrhythmia causing hemodynamic repercussions (IIa-C) and in those with restrictive cardiomyopathy (I-C) who are expected to survive > 1 year. Finally, Chagas disease is addressed for the first time, with a recommendation for ICD implantation in patients with Chagas cardiomyopathy and LVEF < 40% (IIa-C).

Unfortunately, evidence remains scarce in genetic arrhythmia syndromes, and 86% (31 of 36) of the related recommendations are based on Level C evidence. The only recommendations with Level B evidence are those for long QT syndrome, which has been evaluated in registries including large numbers of patients and lengthy follow-up periods.

One innovation in the section on inherited primary arrhythmia syndromes is that diagnostic criteria have been defined for each of the diseases included (with the exception of early repolarization syndrome). These criteria were proposed in a previous expert consensus statement,15 but certain small modifications have been made (Table 2).

Programmed ventricular stimulation is not recommended in patients with long QT syndrome, short QT syndrome, or catecholaminergic polymorphic VT. However, analysis of sustained ventricular arrhythmia inducibility in Brugada syndrome is still considered optional (IIb-C), despite the huge controversy generated by the negative outcome in the PRELUDE study.16 ICD implantation remains the therapy of choice for survivors of cardiac arrest secondary to polymorphic VT or ventricular fibrillation (VF). Nonetheless, evidence is scarce supporting the ICD indication for primary prevention in this group of diseases, and few related recommendations are included.

It would be of value to establish recommendations for screening of family members in primary arrhythmias.

With regard to idiopathic right ventricular outflow tract tachycardia, the recommendation for ablation has been raised from I-C to I-B in patients refractory to, intolerant of, or refusing anti-arrhythmic therapy. The recommendation also includes patients with a depressed LVEF attributable to a high burden of ventricular extrasystoles.

Another important innovation related to the management of arrhythmogenic substrates of the outflow tract is that the type of management will differ according to the presumed origin. Catheter ablation is recommended as first-line therapy (I-B) if the suspected origin is the right ventricular outflow tract, whereas therapy with sodium channel blockers would be the first approach if the suspected origin is the left ventricle (LV) (aortic cusp, LV outflow tract, LV outflow tract epicardium, or pulmonary artery) (I-C). The guidelines mention that ablation procedures are more complex in suspected left sources, as combined access approaches are often required. Hence, left ventricular outflow tract ablation should only be done in symptomatic patients who have failed at least 1 class I-C drug and in centers with considerable ablation experience (II-B).

A limitation of this section is that there are no recommendations for patients with a specific suspicion of tachycardiomyopathy due to VT/VE of the LV outflow tract.

A new subsection has been created regarding the management of idiopathic LV and papillary muscle tachycardia, and mitral and tricuspid annular tachycardia. Catheter ablation is considered the first-line treatment (I-B) in patients with symptomatic idiopathic LV tachycardias (fascicular, bundle branch, Purkinje system, or interfascicular), whereas drug therapy with calcium channel blockers, beta-blockers or class I-C drugs is recommended as a second-line option (I-C). As to papillary muscle and annular tachycardias, the guidelines have issued a new II-B indication for ablation, whereas drug therapy would be the initial treatment of choice (I-A).

The document recognizes that the diagnosis of idiopathic VF is currently by exclusion, although our knowledge of this condition may advance in the future. ICD placement remains a treatment standard (I-B) in patients without structural heart disease who have survived VF, and for the first time, catheter ablation is granted this same level of evidence for treating VE clearly proven to trigger VT/VF or repeated ICD shocks.

There is a new specific section for patients with short-coupled torsade de pointes VT. ICD placement is recommended for the initial management (I-B), with later use of verapamil and ablation of the triggers to prevent electrical storm or recurrent shocks.

Although this section contains numerous changes, all the recommendations remain at evidence level C. There is 1 new reco-mmendation (Class IIb) that includes both persistent myocardial inflammatory infiltrates on biopsy and abnormal fibrosis on MRI as risk factors for SCD, thus supporting ICD placement. Ventricular arrhythmias can develop in 2 different scenarios:

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  Acute myocarditis with refractory VT and severe heart failure is associated with a very poor short-term prognosis in patients with giant cell myocarditis. However, in survivors of the acute phase, the later course is relatively favorable. This life-threatening presentation justifies inclusion of a new recommendation (Class I) to refer these patients to specialized centers.

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  Myocarditis leading to inflammatory cardiomyopathy has a risk profile for SCD similar to that of dilated cardiomyopathy.

As was mentioned above, these new guidelines include the use of wearable ICD, such as the LifeVest 4000 (ZOLL Lifecor Corp., United States), as bridge therapy (Class IIa).

The discussion of these 3 conditions has been notably reduced, as is reasonable considering that they are rare causes of SCD and usually not due to ventricular arrhythmias, but instead to atrioventricular block (AVB) or hemodynamic changes.

Because of the high recurrence rate of VT in cardiac sarcoidosis, ICD implantation has a Class IIa recommendation after the acute episode and Class IIb when the condition presents with cardiac arrest or poorly tolerated VT. Very few patients have sarcoidosis in Spain; the incidence is 1 to 4 per 100 000 inhabitants, a lower value than in the rest of Europe (around 15 per 100 000).

This section incorporates 3 new recommendations: ICD implantation has recognized benefits and is recommended in patients with general indications for primary or secondary prevention after surgery (Class I), there is a need to rule out bundle branch re-entry VT in patients who develop VT following surgery (Class IIa), and surgical treatment is recommended in patients with acute aortic regurgitation due to endocarditis associated with VT (Class I).

The section on psychiatric patients has grown disproportionately, without providing innovations. The most important causative mechanism of SCD in these patients seems to be QT interval prolongation, which is associated with the development of torsade de pointes VT. Three (quite evident) Class I recommendations are offered: 1) dosage adjustment or discontinuation of antipsychotic drug therapy if the QTc reaches a length of more than 500ms or increases more than 60ms from the baseline value; 2) monitoring of plasma potassium concentration to avoid hypokalemia, and 3) avoidance of simultaneous use of more than 1 drug prolonging the QT interval. It is surprising that the fourth recommendation, electrocardiography (ECG) evaluation to measure the QT interval before initiation of drug therapy has received only a Class IIa grade, and there is no recommendation for a new QT measurement immediately after the first or second dose of the drug.

Relative to the 2006 guidelines, there is a new reference to the possibility of SCD in epilepsy. Although the guidelines alert to the need for screening to investigate cardiac diseases that might mimic epilepsy, there are no firm recommendations regarding this important point.

In the section on neuromuscular disorders, arrhythmia risk is reviewed in patients with muscular dystrophies. Annual cardiologic follow-up in this population is a Class I recommendation for asymptomatic patients, and the general recommendations are applied in patients who develop VT/VF or severe left ventricular dysfunction (I-C). The Class IIb recommendation for pacemaker implantation is maintained for any degree of AVB appearing in certain dystrophies (Steinert disease, Kearns-Seyre syndrome, and limb-girdle muscular dystrophy) because of the risk of rapid progression. ICD placement is also recommended in patients with Emery-Dreifuss muscular dystrophy and limb-girdle muscular dystrophy type 1B associated with laminin A or C mutations, especially those with malignant VT.

Together with the 2 recommendations for pregnant women included in the 2006 guidelines (electrical cardioversion [ECV] for VT and poorly tolerated VF, and beta-blockers for long QT syndrome, both Class I), 2 additional Class I recommendations are offered in the update: use of oral metoprolol, propranolol, or verapamil is allowed for maintenance therapy of idiopathic sustained VT, and ICD implantation is recommended if an indication emerges during pregnancy. However, the authors specify that it may be reasonable to wait in the case of peripartum cardiomyopathy, as the condition remits spontaneously in more than half the patients. There is no reference to the use of a defibrillator vest, although it would fulfill the same functions as in myocarditis.

There is a new classification of antiarrhythmic drugs according to their teratogenic potential, and recommendations are provided for acute intravenous therapy in hemodynamically stable VT (sotalol or procainamide, Class IIa) or unstable VT refractory to ECV (amiodarone, Class IIa). The guidelines stress the contraindication for class I-C agents during pregnancy (Class I): angiotensin converting enzyme inhibitors (ACEI) (teratogenicity), angiotensin II receptor blockers II (ARBs) (fetotoxicity), and renin inhibitors, although there are no data on this last drug in humans.

It is surprising that the recommendation for catheter ablation in drug-refractory and poorly-tolerated VTs is rated Class IIb. Furthermore, a specific recommendation for the “fluoroscopy 0” approach to reduce radiation dose in ablation procedures has not been included.

Another innovation is the inclusion and extensive discussion of obstructive sleep apnea syndrome. The guidelines indicate that this condition should be included in the differential diagnosis of bradyarrhythmias (Class IIa) and be considered a risk factor for SCD (Class IIb).

The recommendations for drug-related pro-arrhythmia have been simplified, and the tables in the previous guidelines have been substituted for a link (http://www.crediblemeds.org) to a website from the University of Arizona that lists all the drugs and drug interactions affecting the QT interval. Only 2 recommendations have been established in relation to suspected drug-induced arrhythmia: 1) withdraw the agents after excluding other possible causes (Class I), and 2) despite drug discontinuation, evaluate whether the patient continues to have a substantial risk of VT/VF advising ICD implantation (Class IIa).

Placement of an ICD following heart transplantation may be appropriate in high-risk patients: cardiac arrest, LVEF <35%, severe graft vasculopathy or syncope of unexplained origin.

The Class I recommendation advising careful history taking in athletes has been maintained. The update insists on the contradiction of recommending (Class I) echocardiographic or MRI assessment when abnormal ECG findings suggest a heart disease. A Class IIa rating is given to the recommendation for echocardiography and physical examination in both younger and middle-aged individuals before participating in sports (in the previous guidelines, Class IIb).

These guidelines have added (IIa) an evaluation protocol for assessing middle aged/ senior individuals who wish to engage in sports, adapted from the proposal of the European Association of Cardiovascular Prevention and Rehabilitation. Key elements include the level of activity of the sport and the individual's ESC risk score. Clinical history taking, physical examination, and ECG assessment are recommended in those with higher risk. There are obvious cost-effectiveness concerns related to this strategy, but some studies have reported a cost of $199 per athlete, lower than that of the sports equipment.

Finally, these guidelines introduce a Class IIa recommendation advising training of the staff and coaches at sports facilities in cardiopulmonary resuscitation and in proper use of external defibrillators.

Two recommendations are defined for catheter ablation: patients with Wolff-Parkinson-White syndrome resuscitated from cardiac arrest due to atrial fibrillation-related VF (Class IB) and symptomatic patients or those with an effective refractory period of the accessory pathway (ERPAP) ≤240ms (IIa-B). This latter recommendation constitutes a change with respect to the last (2003) guidelines on supraventricular tachycardias from the ACC/AHA/ESC, in which ablation in patients with Wolff-Parkinson-White syndrome was a Class IB recommendation.

Two Class IIa recommendations recognize the following needs: 1) to consider ICD deactivation according to the desires of the patient or family when clinical conditions deteriorate, and 2) before DAI implantation and during follow-up, to determine the patient's wishes regarding end-of-life issues.