Sudden death in ischemic heart disease - 2017. 2017

Alfred E Buxton
Harvard Medical School, Boston, MA, USA; Clinical Electrophysiology and ECG Laboratories, Beth Israel Deaconess Medical Center, Boston, MA, USA.

At this time, we find ourselves with an abundance of guidelines for management of patients with manifest ventricular tachyarrhythmias, or at risk for such arrhythmias, in patients with coronary heart disease (CHD). The guidelines are focused primarily on the "appropriate use" of the implantable cardioverter/defibrillator (ICD). Unfortunately, the bulk of the guidelines have very little basis in the underlying pathophysiology responsible for sudden cardiac death (SCD) in patients with CHD. Rather, they are based primarily on the results of randomized clinical trials that merely sought to take broad populations at elevated total mortality risk and determining whether the ICD can reduce overall mortality. The trials were not aimed at elucidating or exploiting the varying pathophysiology responsible for the ventricular arrhythmias responsible for most sudden deaths in this setting. The goal of the trials is appropriate - to improve the survival. The problem with promoting trials that solely determine whether a broad-based population (identified by one parameter such as ejection fraction that bears no direct relation to the pathogenesis of arrhythmias) derives a survival benefit from a therapy such as the ICD, is that many patients that could benefit from the ICD are missed (not covered by the guidelines), and many patients that will never benefit from the ICD are exposed to its risks and costs. How can we advance the use of potent, but expensive therapies that carry risk such as the ICD to improve survival of patients with CHD today? There are several avenues worth pursuing, both for short-term as well as long-term gain. First, there are several models shown to have the potential to identify patients currently covered by the guidelines for ICD use, that are highly unlikely to benefit, because of the existing co-morbidities. These models are likely to be valid because there is significant overlap in the parameters identified in each model, and they have been tested retrospectively in a variety of study populations. These models are not likely to be incorporated into use guidelines, until they have been tested prospectively in a randomized trial in a contemporary patient population. This can, and should be done. Use of such a model, based on noninvasive, readily available clinical markers offers the possibility of improving the efficiency with which ICDs are used to reduce the risk of SCD in CHD patients. Second, we need to recognize the fact that SCD in this population is a result of multiple potential mechanisms. And, the electrophysiologic substrates underlying these mechanisms are influenced by interactions with the autonomic nervous system and hemodynamic conditions. While most out-of-hospital cardiac arrests do not occur in persons with overt heart failure, the presence of heart failure clearly increases the risk for SCD, likely by a variety of mechanisms. There is increasing evidence that altered left ventricular geometry may not only reduce LV mechanical efficiency, but may also have direct effects on the electrophysiologic substrate. Although there is an abundance of evidence supporting the importance of autonomic interactions in the genesis of spontaneous arrhythmias, the utility of prospectively measuring autonomic indices to predict future arrhythmic events has to date not proven to be useful. Of course, that is not to discount the significant impact of beta-adrenergic blockade on survival and reducing arrhythmic events. Future works must focus more on both animal models of post-infarction arrhythmias, as well as integrating findings from such studies into human physiology, with subsequent testing in the form of randomized clinical trials.

UI MeSH Term Description Entries
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000319 Adrenergic beta-Antagonists Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety. Adrenergic beta-Antagonist,Adrenergic beta-Receptor Blockader,Adrenergic beta-Receptor Blockaders,beta-Adrenergic Antagonist,beta-Adrenergic Blocker,beta-Adrenergic Blocking Agent,beta-Adrenergic Blocking Agents,beta-Adrenergic Receptor Blockader,beta-Adrenergic Receptor Blockaders,beta-Adrenoceptor Antagonist,beta-Blockers, Adrenergic,beta-Adrenergic Antagonists,beta-Adrenergic Blockers,beta-Adrenoceptor Antagonists,Adrenergic beta Antagonist,Adrenergic beta Antagonists,Adrenergic beta Receptor Blockader,Adrenergic beta Receptor Blockaders,Adrenergic beta-Blockers,Agent, beta-Adrenergic Blocking,Agents, beta-Adrenergic Blocking,Antagonist, beta-Adrenergic,Antagonist, beta-Adrenoceptor,Antagonists, beta-Adrenergic,Antagonists, beta-Adrenoceptor,Blockader, Adrenergic beta-Receptor,Blockader, beta-Adrenergic Receptor,Blockaders, Adrenergic beta-Receptor,Blockaders, beta-Adrenergic Receptor,Blocker, beta-Adrenergic,Blockers, beta-Adrenergic,Blocking Agent, beta-Adrenergic,Blocking Agents, beta-Adrenergic,Receptor Blockader, beta-Adrenergic,Receptor Blockaders, beta-Adrenergic,beta Adrenergic Antagonist,beta Adrenergic Antagonists,beta Adrenergic Blocker,beta Adrenergic Blockers,beta Adrenergic Blocking Agent,beta Adrenergic Blocking Agents,beta Adrenergic Receptor Blockader,beta Adrenergic Receptor Blockaders,beta Adrenoceptor Antagonist,beta Adrenoceptor Antagonists,beta Blockers, Adrenergic,beta-Antagonist, Adrenergic,beta-Antagonists, Adrenergic,beta-Receptor Blockader, Adrenergic,beta-Receptor Blockaders, Adrenergic
D000889 Anti-Arrhythmia Agents Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade. Anti-Arrhythmia Agent,Anti-Arrhythmia Drug,Anti-Arrhythmic,Antiarrhythmia Agent,Antiarrhythmia Drug,Antiarrhythmic Drug,Antifibrillatory Agent,Antifibrillatory Agents,Cardiac Depressant,Cardiac Depressants,Myocardial Depressant,Myocardial Depressants,Anti-Arrhythmia Drugs,Anti-Arrhythmics,Antiarrhythmia Agents,Antiarrhythmia Drugs,Antiarrhythmic Drugs,Agent, Anti-Arrhythmia,Agent, Antiarrhythmia,Agent, Antifibrillatory,Agents, Anti-Arrhythmia,Agents, Antiarrhythmia,Agents, Antifibrillatory,Anti Arrhythmia Agent,Anti Arrhythmia Agents,Anti Arrhythmia Drug,Anti Arrhythmia Drugs,Anti Arrhythmic,Anti Arrhythmics,Depressant, Cardiac,Depressant, Myocardial,Depressants, Cardiac,Depressants, Myocardial,Drug, Anti-Arrhythmia,Drug, Antiarrhythmia,Drug, Antiarrhythmic,Drugs, Anti-Arrhythmia,Drugs, Antiarrhythmia,Drugs, Antiarrhythmic
D016757 Death, Sudden, Cardiac Unexpected rapid natural death due to cardiovascular collapse within one hour of initial symptoms. It is usually caused by the worsening of existing heart diseases. The sudden onset of symptoms, such as CHEST PAIN and CARDIAC ARRHYTHMIAS, particularly VENTRICULAR TACHYCARDIA, can lead to the loss of consciousness and cardiac arrest followed by biological death. (from Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 7th ed., 2005) Cardiac Sudden Death,Sudden Cardiac Death,Cardiac Arrest, Sudden,Sudden Cardiac Arrest,Arrest, Sudden Cardiac,Cardiac Arrests, Sudden,Cardiac Death, Sudden,Death, Cardiac Sudden,Death, Sudden Cardiac,Sudden Death, Cardiac
D017147 Defibrillators, Implantable Implantable devices which continuously monitor the electrical activity of the heart and automatically detect and terminate ventricular tachycardia (TACHYCARDIA, VENTRICULAR) and VENTRICULAR FIBRILLATION. They consist of an impulse generator, batteries, and electrodes. Cardioverter-Defibrillators, Implantable,Implantable Cardioverter Defibrillator,Implantable Cardioverter-Defibrillators,Implantable Defibrillators,Cardioverter Defibrillator, Implantable,Cardioverter Defibrillators, Implantable,Cardioverter-Defibrillator, Implantable,Defibrillator, Implantable,Defibrillator, Implantable Cardioverter,Defibrillators, Implantable Cardioverter,Implantable Cardioverter Defibrillators,Implantable Cardioverter-Defibrillator,Implantable Defibrillator
D017202 Myocardial Ischemia A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (CORONARY ARTERY DISEASE), to obstruction by a thrombus (CORONARY THROMBOSIS), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (MYOCARDIAL INFARCTION). Heart Disease, Ischemic,Ischemia, Myocardial,Ischemic Heart Disease,Disease, Ischemic Heart,Diseases, Ischemic Heart,Heart Diseases, Ischemic,Ischemias, Myocardial,Ischemic Heart Diseases,Myocardial Ischemias
D058687 Out-of-Hospital Cardiac Arrest Occurrence of heart arrest in an individual when there is no immediate access to medical personnel or equipment. Out-of-Hospital Heart Arrest,Cardiac Arrest, Out-of-Hospital,Cardiac Arrests, Out-of-Hospital,Heart Arrest, Out-of-Hospital,Heart Arrests, Out-of-Hospital,Out of Hospital Cardiac Arrest,Out of Hospital Heart Arrest,Out-of-Hospital Cardiac Arrests,Out-of-Hospital Heart Arrests

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