Dr. Safi‘Tis the season to get a flu shot. Researchers from the Department of Cardiothoracic and Vascular Surgery have discovered that flu season also is the season for acute aortic dissection (AAD).

AAD is a life-threatening condition in which blood leaks from the aorta, the major artery that carries blood from the heart to the body. The leak is often caused by a tear in the inside wall of the aorta. The most common symptom of aortic dissection is sudden and severe pain in the chest or upper back.

Researchers at The University of Texas Health Science Center at Houston compared national flu activity from the U.S. Centers for Disease Control to monthly admissions for AAD at their center for 2001-13.

They found:

  • Doctors treated 869 AAD patients at UTHealth during the period.
  • Admissions for AAD were highest in November-March (3.1 per month during this period compared to 2.1 per month for the remaining months).
  • Flu activity (percent of office visits for flu-like illness) averaged 2.6 percent during the peak AAD period (November-March) compared to 1.1 percent in the remaining months.
  • A mathematical model showed statistically significant seasonality and showed type A dissection and flu activity moving cyclically and generally in synchrony throughout the period.
  • Type A dissection was significantly linked with peak flu activity.

Type A dissection, the most devastating type of AAD, involves the ascending aorta and/or aortic arch and, possibly, the descending aorta. Type A generally requires surgery.

“We suspect that flu creates an inflammatory reaction that could theoretically increase chances of dissection in susceptible individuals,” said Dr. Harleen Sandhu, study senior researcher and research coordinator in the Department of Cardiothoracic and Vascular Surgery. “Further research is needed to elucidate the causative pathways underlying this association.”

This research was presented at the American Heart Association’s Scientific Sessions 2014 in Chicago.

-American Heart Association