A friend on mine called recently and he was pretty shaken up. A business associate of his in his fifties with 5 kids and seemingly healthy, collapsed at a little league game and died. He said they told his family he had a massive heart attack. This story is repeated too often. The press and lay public often confuse cardiac arrest and heart attack. Some of the confusion occurs because both of these problems start with a sudden onset and require immediate medical attention.
During a heart attack, a plaque in a coronary artery suddenly becomes unstable and breaks open. The tissue in the exposed plaque causes a thrombus (clot) to form at the site of the ruptured plaque. Plaques that rupture are often less than 70% occlusive in the artery and cause no symptoms prior tot he rupture. Once the thrombus forms a narrowing that was less than 70% goes to 100% and a heart attack occurs. Once the thrombus forms all of the heart muscle beyond the 100% blockage does not receive blood or oxygen and that area of the heart muscle starts to die. The most common reason that patients die during a heart attack prior to arrival to the hospital is that they suffer a cardiac arrest.
Cardiac arrest is the most dramatic of all medical emergencies as a seemingly vibrant and healthy person suddenly collapses and has no pulse or blood pressure and is clinically dead. During a cardiac arrest, the heart’s native rhythm is disrupted and the heart rhythm stops. Often initially the cardiac rhythm goes into ventricular tachycardia or ventricular fibrillation. Both of these rhythms are very treatable with defibrillation. With time, this initial rhythm often degenerates to asystole, no heart rhythm. 70% of the time a cardiac arrest is precipitated by an acute coronary syndrome from a coronary plaque rupture that causes a heart attack. A cardiac arrest can occur with a small heart attack or a big heart attack. Size doe not matter. Cardiac arrests can also be seen with abnormal cardiac muscle problems (cardiomyopathy), genetic cardiac abnormalities (long QT), electrolyte imbalance and other causes of cardiac arrest.
Both conditions are cardiac emergencies and require rapid attention. However, a cardiac arrest requires immediate attention as the person is clinically dead. Every minute that passes increases the mortality rate by 10%. Call 911. Start immediate CPR. Push on the chest hard and fast. Send someone for a defibrillator (AED) if one is available.
The survival rates for out of hospital cardiac arrest are not good but can be improved. There is such a fatalistic approach by many in the press, public and medical circles about out of hospital cardiac arrest. With increased education on what to do and increased rates of bystander CPR we believe that more people will survive a cardiac arrest.(Reprinted from the AHA)
For further information please see this excellent review about cardiac arrest and a triathlete from Dr. Larry Creswell. http://www.athletesheart.org/2014/04/laurent-vidal-and-cardiac-arrest/