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Ventricular arrhythmias and heart failure: updated advice on implantable cardiac devices from NICE


In final draft guidance NICE ( National Institute for Health and Care Excellence ) has defined which heart devices ( known as implantable cardiac devices ) are the most clinically and cost effective.

The draft guidance is an update of two existing pieces of NICE Guidance: a) NICE guidance on the use of implantable cardioverter defibrillators ( ICDs ) in people who have ventricular arrhythmias; b) NICE guidance on cardiac resynchronisation therapy for people with heart failure. People with heart failure also have an increased risk of developing life threatening ventricular arrhythmias, and sudden cardiac death is the most common cause of death in people with mild to moderate heart failure.

Only the recommendations about the use of the different implantable cardiac devices for people at risk of sudden cardiac death because of heart failure have been updated in this draft guidance. There was no new evidence on the use of ICDs for people who have survived an episode of ventricular tachycardia or ventricular fibrillation, for people with specific inherited cardiac conditions who have a high risk of sudden death or who have undergone surgical repair of congenital heart disease.

People who survive a life-threatening ventricular arrhythmia are at high risk of further arrhythmias and are usually fitted with an ICD.
An ICD is a small battery powered device that is put into the upper chest below the left shoulder. Leads from the device go through a vein into the heart to control the rate ( pace ) of the heartbeat. They continually monitor for an irregular heartbeat, and deliver a small electric shock to return the heartbeat to its normal rhythm ( defibrillate ) if necessary.

The aim of cardiac resynchronisation therapy ( CRT- also known as cardiac resynchronisation pacemaker [ CRT-P ] ) is to improve the heart's pumping efficiency by bringing the pumping action of the heart chambers back in time with each other.
Another type of CRT, called CRT-D ( combining CRT-P and ICD devices ) defibrillates the heart internally if it starts beating irregularly and improves the heart's pumping efficiency.

The draft guidance states that:

A) Implantable cardioverter defibrillators ( ICDs ) are recommended as options for:

a) treating people with previous serious ventricular arrhythmia, that is, for people who, without a treatable cause: have survived a cardiac arrest caused by either ventricular tachycardia ( VT ) or ventricular fibrillation or have spontaneous sustained VT causing syncope or significant haemodynamic compromise or have sustained VT without syncope or cardiac arrest, and have an associated reduction in left ventricular ejection fraction ( LVEF ) of less than 35% but their symptoms are no worse than class III of the New York Heart Association ( NYHA ) functional classification of heart failure.

b) treating people who: have a familial cardiac condition with a high risk of sudden death, such as long QT syndrome, hypertrophic cardiomyopathy, Brugada syndrome or arrhythmogenic right ventricular dysplasia or have undergone surgical repair of congenital heart disease.

B) Implantable cardioverter defibrillators and cardiac resynchronisation therapy ( CRT with defibrillator [ CRT-D ] and CRT with pacing [ CRT-P ] ) are recommended as treatment options for people with heart failure who have left ventricular dysfunction with an LVEF of 35% or less.

About arrhythmias

The average survival of adults with an out of hospital episode of ventricular arrhythmia has been reported as low as 7%. With appropriate treatment and secondary preventive strategies, recent studies have reported 5 year survival of 69 to 100%.

Many patients presenting with arrhythmias with or without symptoms are treated with antiarrhythmic drug therapy. Antiarrhythmic drugs are often not effective and need constant titration which can be confusing for patients and lead to missing doses, taking the wrong dose or overdose. Many antiarrhythmic drugs result in tiredness and inability to perform day to day activities, dependence on carers and consequently increase the risk of depression. Antiarrhythmic drugs also have many side effects on the thyroid, liver or lungs.

Chronic prophylactic antiarrhythmic drug therapy aims to suppress the development of arrhythmias, but does not terminate an arrhythmia once it is initiated. People who survive a first episode of a life-threatening ventricular arrhythmia are at high risk of further episodes and usually treated with implantable cardioverter defibrillators ( ICDs ).

Risk factors for sudden cardiac death include age, hereditary factors, having high risk of for coronary artery disease, inflammatory markers, hypertension, left ventricular hypertrophy, conduction abnormalities ( for example left bundle-branch block ), obesity, diabetes and lifestyle factors.

About heart failure

Heart failure is a chronic condition predominantly affecting people over the age of 50 years. It is a condition caused by any structural or functional cardiac disorder that impairs the heart's ability to function efficiently as a pump to support circulation. It is characterised by breathlessness, fatigue and fluid retention. About 900,000 people in England and Wales have heart failure, of which at least half have LVSD.

Clinically heart failure is classified using the New York Heart Association ( NYHA ) functional class, ranging from Class I ( no limitation of physical activity ) to Class IV ( symptomatic at rest and discomfort from any physical activity ).

Heart failure is also classified based on which heart function or which side of the heart is most affected: some patients have heart failure due to left ventricular systolic dysfunction ( LVSD ) which is associated with a reduced left ventricular ejection fraction ( left heart failure or biventricular failure ); while others have only right heart failure with a preserved ejection fraction.

Management of chronic heart failure in adults in primary and secondary care initially recommends pharmacological treatment. However, as the condition becomes more severe, cardiac function and symptoms may no longer be controlled by pharmacological treatment and require invasive procedures. Cardiac function and heart failure symptoms may be improved by the implantation of a cardiac rhythm device which can sense and stimulate the atria, right and left ventricles independently. ( Xagena )

Source: NICE, 2014

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