It has been half a century since a Miami heart surgeon first reported the ability to save human life using external cardiac massage. However, progress in this area has paled in comparison with other life-threatening cardiac diseases. Although estimates vary considerably, out of hospital cardiac arrest afflicts approximately 300,000 Americans per year – fewer than 8% survive to hospital discharge. Survival rates vary in different regions and communities. Densely populated urban areas, which have robust medical services, such as New York and Chicago, report survival rates of 1.4% t 2.0%. Moreover, a nearly 500% difference in survival rates has been reported across various communities. Unlike myocardial infarction, which has demonstrated a 3-fold decrease in acute mortality over the past three decades, survival rates for sudden cardiac death have showed only the most modest improvement. Why is this?
The first and most compelling challenge in this lethal condition is timing – every minute that the brain and other vital organs are deprived of oxygen and other vital nutrients, the chance of survival decreases by approximately 10%. Minutes can literally determine the difference between life and death. Even in the case of myocardial infarction (heart attack) and stroke, where minutes certainly do count, and the more prompt the treatment the better the result, the timing of critical treatment is measured in hours (1-3) rather than minutes. Even cardiac arrest which occurs in the hospital setting has been shown to have a grim prognosis.
The next major challenge is the unpredictable nature of the event. Although many former heart attack victims may be at risk for an arrhythmic or ischemic event and may or may not have a device implanted to treat this situation, for the vast majority of those who suffer out of hospital cardiac arrest, this lethal event is the first manifestation of their disease. For some, the episode may represent a myocardial infarction, for which known risk factors may have been present even in the absence of any known clinical disease. However, for many others, there may have been a previously unknown genetic predisposition which could have been neither predicted nor anticipated.
Equally daunting is the task of properly treating the victim. Since the victim himself by definition has lost effective cardiac output and therefore lost all effective perfusion to his brain and other vital organs, he is completely incapable of summoning help, even if it were available. If he is alone, he may well pass away unrecognized until some point in the future. If, however, he is not alone, it is incumbent upon those who witness this event to 1) be capable of recognizing it for what it is, and 2) to be able to respond appropriately. For one who is not medically trained, the ability to distinguish between a cardiac arrest, a fainting spell or perhaps even sleep may be a difficult task. If he does recognize that the person in front of him is rapidly dying, the normal response for those without medical training is somewhere between fear and panic. What is in fact required is an immediate summoning of help through the 9-1-1 emergency rescue system, as well as life-saving external cardiac massage. Placing the heal of the palm over the victim’s sternum (breast bone) and compressing two or more inches in rapid succession (ironically, the tempo of the BeeGee’s “Staying Alive” song works nicely), can provide sufficient circulation of the blood and ventilation to sustain someone’s life until help arrives. Recent studies of this simpler “compression only” approach, compared with the more complex traditional cardiopulmonary resuscitation using a combination of compression and mouth-to-mouth intermittent breaths has demonstrated an equal ability to save lives. As soon as possible, electrical cardioversion with an automatic external defibrillator (AED) is needed to shock the heart back into a self-sustaining rhythm. Smart devices now available in many public venues can even guide untrained individuals toward effective shock delivery.
What should be apparent is that what is necessary is a continuum of care rather than a single specific therapy. This is commonly referred to as the “chain of survival”—immediate recognition and activation of emergency services, early and effective chest compression, rapid defibrillation, effective advanced life support by the rescue squad and integrated post-cardiac arrest care by specialized teams and care regimens in the hospital. In upcoming articles, we will focus on how the Florida Heart Research Institute is starting this New Year by building on its foundation of leading edge research and education in the area of sudden cardiac death to improve the outcomes of this devastating disease in our community, in the State, and in the nation as a whole.
