People who suffer a stroke and also have an abnormality in the heart’s electrical activity when they arrive at the emergency room are at a higher risk of dying within 90 days than people who do not have abnormal electrical activity at the time of emergency treatment, according to new research.

The so-called “QTc” interval is a measure of the electrical activity of the heart, as seen on an electrocardiogram, or EKG. An EKG records the waves of activity and its pattern, which is labeled with the letters Q and T. Doctors look for the appropriate intervals between each letter, showing that the heart’s electrical signals are steadily passing through the ventricles of the heart. A prolonged QTc interval means it takes too long for the electrical signal to pass.

Dr. Latha G. Stead of the University of Rochester Medical Center and colleagues studied the medical records of 345 patients who suffered an “ischemic” stroke - the most common type of stroke and one that stems from a blockage of a blood vessel in the brain.

They found that about 35 percent of the patients had a prolonged QTc interval at the time of the emergency department visit. An estimated 81 percent of all patients were expected to survive the next three months. However, only 70.5 percent of the patients with a prolonged QTc interval survived compared with 87.1 percent of the patients without a prolonged QTc interval.

Prolonged QTc intervals can be the result of a rare genetic disorder, medications, electrolyte imbalances, or congenital heart disease, the researchers note.

In cases of stroke, it seems worthwhile for doctors to review the medications a patient is taking and look specifically for those that might prolong the QTc interval, they conclude.

SOURCE: The Journal of Stroke and Cerebrovascular Diseases, online March 20, 2009.