Find out the reason that sudden cardiac death is most likely to occur between 6 a.m. and 10 a.m., and how this might be prevented.

Sudden cardiac death kills about 325,000 Americans every year, and a striking number of these occur in the morning: 6 a.m. to 10 a.m.

This particular sudden cardiac death, says Mukesh Jain, MD, is caused by the “electrical instability” of ventricular fibrillation.

“In all too many cases, there is no second chance,” says Dr. Jain, of Case Western Reserve University in Cleveland. “The first event is the last event.” His team is researching developing drugs that can lower the risk.

Researchers have proposed for many years that the reason sudden cardiac death often happens early in the morning is related to the circadian rhythm and sleep cycle.

Dr. Jain’s team discovered a protein, KLF15, which helps regulate the electrical activity of the heart.

KLF15 fluctuates in the body like clockwork, forming channels that permit substances to enter and exit cardiac cells in a way that’s crucial for ensuring a normal heart rhythm.

The team noted that people with heart failure had lower levels of this protein. They then found that in mice, KLF15 links sudden cardiac death with the circadian rhythm.

Mice with low levels of KLF15 have the same heart problems as do people with sudden cardiac death.

Dr. Jain explains that people who have low KLF15 are “most susceptible to these sudden death episodes that occur in the early morning hours.”

His goal is to come up with a way to boost the KLF15 levels in people who have heart problems; this would, presumably, lower the occurrence of ventricular fibrillation and thus sudden cardiac death.

So the next step is to develop a drug that can boost KLF15. The drug would have to be targeted specifically to the process that involves heart function, so that other processes that KLF15 affects are left alone.

Dr. Jain notes that other researchers are hoping to develop genetic tests that can identify individuals who have mutations involving the KLF15 gene; these patients would be at higher risk of suffering from sudden cardiac death. names the following risk factors for ventricular fibrillation: previous heart attack, cardiomyopathy, cocaine and meth use, among other risk factors.