TUESDAY, March 27 (HealthDay News) -- Patients who are small or underweight are at greater risk for complications during the placement of an implantable cardioverter-defibrillator, a new study indicates.

Implantable cardioverter-defibrillators (ICDs) are devices that shock the heart into beating again if it stops or begins to beat in an irregular manner.

The researchers also found that the most common complications seen among smaller patients were collapsed lungs and hematomas, or blood pooling in the area where the small, battery-powered device is implanted.

"If you are having a defibrillator placed, being underweight may put you at risk for adverse events from the implantation procedure," lead investigator Dr. Jonathan Hsu, a fellow in cardiac electrophysiology at the University of California, San Francisco, said in a news release from the American College of Cardiology.

"Having a lower body mass index may put you at higher risk of having complications, staying in the hospital for longer and even dying from the procedure," Hsu added. Body mass index, or BMI, is a measurement of body fat based on height and weight.

In conducting the study, the researchers examined more than 83,000 cases to determine how body size influences the success of ICD implantation. They found that patients with a low BMI had longer hospital stays, more complications and greater risk for death during or right after the procedure than those who were normal weight or overweight.

Some reasons smaller patients may be at greater risk might include contributing factors such as frailty, malnutrition and coexisting conditions, such as cancer, the study authors theorized. The findings could help doctors better understand patients' risks and help prevent complications from ICD implantation, they said.

"Body size is something that's easily measurable," Hsu said in the news release. "Talking with patients about the benefits and risks is an important part of what we do, and implanters can use this information in counseling patients who may be at higher risk."

Hsu said doctors could also access the chest cavity differently to reduce the risk of collapsed lungs, revise their strategy for anticoagulation medications to reduce the risk of bleeding or use compression bandages to prevent blood pooling in the implantation area.

The study authors noted that their findings could apply to other heart procedures as well.

"Perhaps this pattern isn't just in cardiovascular patients or ICD implant patients," said Hsu. "It's possible that we haven't been looking at underweight patients and their risks closely enough because we've been focusing so much attention on obese patients."

The study was presented Sunday at the American College of Cardiology's annual meeting in Chicago. Any research presented at medical meetings should be viewed as preliminary until it is published in a peer-reviewed medical journal.

More information

The U.S. National Heart, Lung, and Blood Institute provides more information on ICDs.