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Sudden Cardiac Arrest: An Expert Interview With Eric N. Prystowsky, MD


Editor's Note:
Sudden cardiac arrest is a leading cause of death in the United States. Primary care physicians can help identify, counsel, and refer these patients appropriately, as well as minimize the risks for coronary artery disease and, ultimately, sudden cardiac arrest.

Eric N. Prystowsky, MD, is a leading practitioner, investigator, and teacher in the cardiac rhythm management field, as well as Editor-in-Chief of Medscape Cardiac Rhythm Management. He is Director of the Clinical Electrophysiology Laboratory at St. Vincent Hospital, Indianapolis, Indiana, and a Consulting Professor of Medicine at Duke University Medical Center in Durham, North Carolina.

In this interview with Medscape, Dr. Prystowsky relates the essentials of the development and prevention of sudden cardiac arrest for the primary care physician.

Medscape: Recently the Heart Rhythm Society (HRS, formerly the North American Society of Pacing and Electrophysiology, or NASPE) has modified the terminology for one of the key medical events the members of the society must deal with, namely the sudden cardiac failure of a patient, almost always due to a cardiac arrhythmic event. Whereas this has always been referred to as "sudden cardiac death," the term that is now considered to be more correct is "sudden cardiac arrest." Surely this is more than mere semantics -- but what was the reasoning behind this change in terminology?

Eric N. Prystowsky, MD: The term sudden cardiac death is ingrained in the literature and is the correct scientific term for death that occurs without warning and is due to a cardiac arrhythmia, most typically sustained ventricular tachycardia or ventricular fibrillation. Sudden cardiac death is a leading cause of mortality in adults in the United States. The estimates range from approximately 250,000 to 450,000 per year.[1,2] The enormity of this epidemiologic problem has engendered years of research into the mechanisms and prevention of sudden cardiac death, and has resulted in thousands of articles on the subject, all using the term "sudden cardiac death." Why, then, after decades of using this term, has the Heart Rhythm Society Foundation switched to the alternative term "sudden cardiac arrest?"

During the fact-gathering phase for our pilot project on educating physicians and the public on sudden cardiac death, we were surprised to learn that lay people were much more concerned about the possibility of a sudden cardiac arrest than sudden cardiac death. If one compares sudden death to the potential suffering of [a] disease such as cancer, then it is not surprising a patient is not as worried about sudden death. However, the concept of a sudden cardiac arrest did seem to resonate much more with patients and lay people and thus the change in terminology for this project.

Medscape: Speaking to our more general physicians, what are the "red flags" that suggest a patient may be at risk for SCA? Are there less obvious signs?

Dr. Prystowsky: Identification of patients at risk for sudden cardiac arrest is both rather simple and incredibly hard. The task is simple when one searches for certain well-known risk factors that identify a high-risk patient for sudden cardiac death due to a sustained ventricular tachyarrhythmia -- for example, ventricular fibrillation. The most common identifiable patient is one who has had a previous myocardial infarction and is left with a left ventricular (LV) ejection fraction of ≤ 40%. In this subgroup, the highest-risk patients are those with an LV ejection fraction ≤ 30%. Such patients may be asymptomatic or have signs of congestive heart failure. Also at high risk are patients with a nonischemic dilated cardiomyopathy with an LV ejection fraction of ≤ 35%, especially those with a history of congestive heart failure.

Many of the above patient subgroups are not indicated for an implantable cardioverter defibrillator (ICD) and should be evaluated by a cardiologist and preferably a clinical electrophysiologist. Other patient subgroups at risk for sudden cardiac death are those with certain primary electrical abnormalities such as long QT interval or even Wolff-Parkinson-White syndrome, as well as certain patients with hypertrophic cardiomyopathy.

Unfortunately, one of the largest groups of patients at risk for sudden cardiac death is those who have not even declared themselves as having heart disease. Nearly one third of patients who have coronary artery disease present with a cardiac arrest typically associated with their initial myocardial infarction. Overall, there are likely more sudden deaths in patients without any identifiable high risk factors since they are among the other adults in the general population. How to identify one of these individuals before their cardiac arrest is like looking for a needle in a haystack. At this time, there is no ideal test to identify such individuals, and the best prevention is to minimize risk factors for the development of coronary artery disease, including the cessation of smoking, reduction of blood pressure, and evaluation and treatment of lipid disorders.

Medscape: Given that prior MI is a risk factor for SCA, what should patients be told by their physicians following successful coronary revascularization (ie, should patients be informed that they are at risk for SCA)?

Dr. Prystowsky: To prevent sudden death, it is necessary for the physicians to understand who is at risk for a fatal cardiac arrhythmia, as outlined above, and when they encounter such a patient, they should discuss this issue with them. For example, patients with poor LV function who undergo coronary revascularization should have a follow-up appointment with a cardiologist or electrophysiologist within 3 months to re-evaluate their LV function and to determine whether they are a candidate for an ICD. Likewise, a patient who has had an MI and who has significantly reduced LV function should be re-evaluated approximately 40 days after the MI to evaluate the risk for sudden cardiac arrest.

Medscape: What primary preventive efforts can be initiated in the general physician's office for a patient who fits the risk profile outlined above?

Dr. Prystowsky: Prevention of sudden death is not just the province of the cardiologist and the electrophysiologist. In fact, the first line of defense may likely be the primary care physician, whether an internist or family practitioner. These physicians play a vital role in the prevention of coronary artery disease as well as in the identification of patients with coronary artery disease who should be evaluated further for the possibility of an ICD. Patients should have appropriate therapy for hypertension as well as lipid disorders. Those who require medications such as beta blockers and ACE inhibitors or ARBs should receive them. Clearly, the battle against sudden death will not be won only in the cardiologist's and electrophysiologist's offices.

Medscape: When is it time to refer the patient to a specialist?

Dr. Prystowsky: When a patient is identified as a high-risk candidate for a sudden cardiac arrest, they should be sent to a clinical electrophysiologist or at least a cardiologist for further workup. As mentioned above, this includes individuals with coronary artery disease and an LV ejection fraction of ≤ 35% as well as those with nonischemic cardiomyopathy who have an LV ejection fraction ≤ 35% and a history of congestive heart failure. Patients with a prolonged QT interval on the surface electrocardiogram, with and without symptoms, should undergo additional evaluation by an electrophysiologist, and patients with ventricular pre-excitation (WPW syndrome) should also see an electrophysiologist for risk stratification. Many of the patients at potential for sudden death are asymptomatic, but certain symptoms also warrant referral to a cardiologist or electrophysiologist. Symptoms that are worrisome [include] syncope and episodes of rapid palpitations, especially associated with presyncope or syncope. Such individuals should undergo a cardiac workup and may require further therapy from an electrophysiologist or cardiologist.

Supported by an independent educational grant from St. Jude Medical.