If you have heart disease or are at risk for it, brace yourself. The peak hours for sudden cardiac death (SCD)—where the heart’s electrical system short circuits due to a rhythm abnormality, stopping the flow of blood to the brain, heart and the rest of the body, causing the person to collapse and die almost instantly—occur between 6 AM and 10 AM.
For more than 30 years health experts have known the erratic heartbeat responsible for SCD strikes most often during these early morning hours. SCD caused by this electrical instability causes an estimated 325,000 deaths annually. And consider who is at risk—those with known heart disease; a family history of heart disease or SCD; prior cardiac arrest or heart attack; high blood pressure/hypertension; abnormal heart rhythms; congestive heart failure; abnormalities on an EKG test or other diagnosed heart muscle weakness; diabetes; smoking; and recreational drug use. Because the biological clock is disrupted, shift workers may also be at a higher risk. And African Americans are at nearly twice the risk as whites for SCD, they also fare worse in surviving such an episode.
The Missing Link Found
Until now, though, researchers have only had theories as to why dawn could trigger SCD, also known as cardiac arrest, and no good ways to prevent it. But a recently discovered molecular link between a protein known as KLF15 and the body’s natural circadian rhythm could help researchers develop drugs and therapies to help those at risk to wake up without worry.
Normally, KLF15 levels increase upon waking. Experimental studies in laboratory mice where the KLF15 level in their hearts was suppressed had an increased susceptibility to sudden death. Ongoing research has also found that patients with heart disease have lower levels of the protein.
“What it suggests is that if perhaps one could boost the levels of this protein in the heart at the right time, like in the early morning hours, that could be helpful,” says Mukesh Jain, MD, director of the Case Cardiovascular Research Institute at Case Western Reserve University in Cleveland and the researcher responsible for finding the KLF15 link. The research was presented at the meeting of the American Chemical Society this week.
There’s currently no blood test or other mechanism to detect KLF15 levels in patients at risk. “Before we learned about KLF15, we didn’t know what to look for. So at least now we have a target to try to develop a test for,” says Dr. Jain. Until screening tests and therapies to prevent SCD become a reality, Dr. Jain offers these suggestions:
Know the symptoms: For both men and women, lightheadedness is the most common symptom that cardiac arrest might occur. Other symptoms may include chest pressure and shortness of breath. If you experience any of these symptoms, sit down immediately. “If it goes on too long, you may pass out,” Dr. Jain explains.
SCD can occur on its own, or the disruption to the heart’s electrical system can be triggered by a heart attack, which is a blockage in the heart’s blood supply that damages or weakens the heart muscle. SCD is the number one cause of death in heart attacks.
Unlike a heart attack where the victim remains awake while experiencing warning signs, cardiac arrest is often so abrupt, the victim collapses and is, in essence, clinically dead before intervention occurs.
Don’t hesitate: Because the heart’s electrical system is involved CPR alone won’t revive the victim. A defibrillator is needed to restart the heart for any chance of survival.
“Time is of the essence when it comes to sudden cardiac death,” says Dr. Jain. Approximately 95% of those who experience SCD die from it, according to the Heart Rhythm Society, which offers an online risk assessment tool.
If you wake up feeling lightheaded, let someone know and call 911 immediately. “There isn’t a whole lot you can do or anyone in your family can do to help you,” says Dr. Jain. “This recognition of needing urgent defibrillation is why we have defibrillators on airplanes and other public spaces.”
Get a good night’s sleep: Aim for seven to eight hours of sleep, says Dr. Jain. Studies have shown that inadequate sleep may raise your risk of cardiovascular disease. If you have disrupted sleep, Jain suggests being screened for sleep apnea, a common, chronic disorder marked by numerous pauses in breathing while you sleep, often accompanied with loud snoring or choking sounds. An estimated 18 million Americans have sleep apnea, but most remain undiagnosed. Obesity is the number one risk factor for developing sleep apnea.
“If you do have disrupted sleep, it does increase your risk for arrhythmias,” says Dr. Jain. “There are ways to treat sleep apnea which would one, give you a more restful sleep and two, decrease your risk of electrical abnormalities of the heart, one of which is sudden cardiac death.”
Consider delaying your morning workout: If you have a flexible schedule, Dr. Jain says a case can be made for working out later in the day.But don’t give up your morning trip to the gym if that’s the only time you can do it. Just start off slowly, and build up.
“It’s still better to participate in exercise, even if it’s in the morning than not doing it at all because the beneficial effects far outweigh any risk an individual person might be subject to in the early morning hours,” says Dr. Jain.
If you currently have heart disease and are on medication for it, Dr. Jain suggests taking those prior to doing any morning exercise.
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