Signs of ‘sudden’ cardiac death may come weeks before: study
Signs of approaching “sudden” cardiac arrest, an electrical malfunction that stops the heart, usually appear at least a month ahead of time, according to a study of middle-age men in Portland, Oregon.
“We’re looking at how to identify the Tim Russerts and Jim Gandolfinis - middle aged men in their 50s who drop dead and we don’t have enough information why,” said Sumeet Chugh, senior author of the study and associate director for genomic cardiology at the Cedars-Sinai Heart Institute in Los Angeles.
Some 360,000 out-of-hospital cardiac arrests occur each year in the United States, largely involving middle-aged men, with only 9.5 percent surviving, according to the American Heart Association.
Patients can survive if they are given Cardiopulmonary resuscitation (CPR) immediately and their hearts are jolted back into normal rhythm with a defibrillator.
Earlier clinical trials have focused only on symptoms or warnings signs within an hour of such attacks. But Chugh’s study set out to determine whether signs and symptoms occurred as much as a month before sudden cardiac arrests.
Researchers went back and examined medical records of men 35 to 65 years old after they had out-of-hospital attacks. In addition, paramedics reaching the scene of fatal attacks asked family members what signs and symptoms the patient may have had in preceding weeks.
What Is Sudden Cardiac Arrest?
Sudden cardiac arrest (SCA) is a condition in which the heart suddenly and unexpectedly stops beating. If this happens, blood stops flowing to the brain and other vital organs.
SCA usually causes death if it’s not treated within minutes.
To understand SCA, it helps to understand how the heart works. The heart has an electrical system that controls the rate and rhythm of the heartbeat. Problems with the heart’s electrical system can cause irregular heartbeats called arrhythmias (ah-RITH-me-ahs).
There are many types of arrhythmias. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. Some arrhythmias can cause the heart to stop pumping blood to the body - these arrhythmias cause SCA.
SCA is not the same as a heart attack. A heart attack occurs if blood flow to part of the heart muscle is blocked. During a heart attack, the heart usually doesn’t suddenly stop beating. SCA, however, may happen after or during recovery from a heart attack.
Most people who have SCA die from it - often within minutes. Rapid treatment of SCA with a defibrillator can be lifesaving. A defibrillator is a device that sends an electric shock to the heart to try to restore its normal rhythm.
Automated external defibrillators (AEDs) can be used by bystanders to save the lives of people who are having SCA. These portable devices often are found in public places, such as shopping malls, golf courses, businesses, airports, airplanes, casinos, convention centers, hotels, sports venues, and schools.
How Is Sudden Cardiac Arrest Different from a Heart Attack?
Sudden cardiac arrest is not a heart attack (myocardial infarction) but can occur during a heart attack. Heart attacks occur when there is a blockage in one or more of the arteries to the heart, preventing the heart from receiving enough oxygen-rich blood. If the oxygen in the blood cannot reach the heart muscle, the heart becomes damaged.
In contrast, sudden cardiac arrest occurs when the electrical system to the heart malfunctions and suddenly becomes very irregular. The heart beats dangerously fast. The ventricles may flutter or quiver (ventricular fibrillation), and blood is not delivered to the body. In the first few minutes, the greatest concern is that blood flow to the brain will be reduced so drastically that a person will lose consciousness. Death follows unless emergency treatment is begun immediately.
Emergency treatment includes Cardiopulmonary resuscitation (CPR) and defibrillation. CPR is a manual technique using repetitive pressing to the chest and breathing into the person’s airways that keeps enough oxygen and blood flowing to the brain until the normal heart rhythm is restored with an electric shock to the chest, a procedure called defibrillation. Emergency squads use portable defibrillators and frequently there are public access defibrillators (AEDs, ambulatory external defibrillators) in public locations that are intended to be available for use by citizens who observe cardiac arrest.
Among 567 men who had “sudden” arrests, researchers determined 53 percent had symptoms beforehand. Among those with symptoms, 56 had chest pain, 13 percent had shortness of breath and 4 percent had dizziness, fainting or palpitations.
About 80 percent of symptoms happened between four weeks and one hour before the cardiac arrest, researchers said. And although most men had coronary artery disease, just half had been tested for it before their attacks.
“The findings were entirely unexpected,” Chugh said. “We never thought more than half of these middle-aged men would have had warning signs so long before their cardiac arrests. Previously we thought most people don’t have symptoms so we can’t do anything about it.”
Chugh said most people who have the same kinds of symptoms don’t go on to have cardiac arrests.
“Even so, they should seek medical care,” he said. “The message here is, if you have these signs or symptoms, please don’t ignore them: seek healthcare.”
Chugh said he and his colleagues are also attempting to identify people at risk by comparing biologies of those that have had sudden cardiac arrests with sample populations in Portland that have never had cardiac arrests.
What Causes Sudden Cardiac Death?
Most sudden cardiac deaths are caused by abnormal heart rhythms called arrhythmias. The most common life-threatening arrhythmia is ventricular fibrillation, which is an erratic, disorganized firing of impulses from the ventricles (the heart’s lower chambers). When this occurs, the heart is unable to pump blood and death will occur within minutes, if left untreated.
What Are the Risk Factors of Sudden Cardiac Arrest?
There are many risk factors that can increase a person’s risk of sudden cardiac arrest and sudden cardiac death, including the following:
Previous heart attack with a large area of the heart damaged (75% of SCD cases are linked to a previous heart attack).
A person’s risk of SCD is higher during the first 6 months after a heart attack.
Coronary artery disease (80% of SCD cases are linked with this disease).
Risk factors for coronary artery disease include smoking, family history of heart disease, and High cholesterol.
The new findings, from the 11-year-old “Oregon Sudden Unexpected Death Study,” were presented on Tuesday at the annual scientific sessions of the American Heart Association being held in Dallas.
The researchers are conducting similar studies among women. The ongoing study is being funded by the U.S. Centers for Disease Control and Prevention, AHA and the Doris Duke Charitable Foundation.
By Ransdell Pierson and Bill Berkrot