Cardiology: Re-Examining the Protective Properties of Beta-Blockers

The beta-blocker class of drugs is commonly prescribed to manage various conditions including arrhythmias, hypertension and following heart attacks. Beta-blockers are also recommended by the American Heart Association to decrease the occurrence of heart attacks around the time of surgery. Recent findings from a TGRI-led study are providing new insights into the differences that patients either prescribed or not prescribed beta-blockers experience during the perioperative period which includes pre-surgery, surgery and post-surgery.

Dr. Scott Beattie and colleagues Drs. Dumina Wijeysundera, Keyvan Karkouti, and Stuart McCluskey reviewed records from more than 4,000 noncardiac, nontransplant surgical patients who were at low risk for cardiac complication. Their findings showed that patients who were taking beta-blockers at the time of surgery had a history of hypertension, diabetes, renal failure, coronary artery disease, peripheral vascular disease, and congestive heart failure more often than those patients who were not taking beta-blockers. After adjusting for these pre-operative differences using a statistical tool called propensity score matching they found heart attacks occurred more frequently in patients who were on beta-blockers.

As explained by Dr. Beattie, “What is new and important in these findings is that major cardiac complications and mortality were increased for those patients prescribed beta-blockers who had more than a 35% drop in hemoglobin concentration”—an important finding for health care teams. Blood loss and acute anemia are very frequent occurrences in surgery. Until future studies can be conducted, it would be prudent to transfuse patients earlier than is currently recommended in patients taking beta blockers to avoid the 35% drop in hemoglobin. Our results here point to the need for a larger study.”

Find this story on the web at: www@uhnresearch.ca