About 20 percent of people who received implantable cardioverter-defibrillators (ICDs) did not meet the guidelines for receiving the heart-jolting device, according to a new study.

The study was based on more than 100,000 patients, and the researchers found that those who didn't meet the guidelines for receiving the implant had a significantly higher risk of in-hospital death than those who met criteria for receiving an ICD.

Several randomized controlled trials have shown the effectiveness of ICDs for preventing sudden cardiac death in patients with advanced systolic heart failure. But practice guidelines do not recommend using an ICD for primary prevention in patients recovering from a heart attack or coronary artery bypass graft surgery, or those with severe heart failure symptoms or a recent diagnosis of heart failure.

"The degree to which physicians in routine clinical practice follow these evidence-based recommendations is not clear," the authors wrote.

The study was based on data submitted to the National Cardiovascular Data Registry-ICD Registry between January 2006 and June 2009, and was led by Dr. Sana M. Al-Khatib, of the Duke Clinical Research Institute in Durham, N.C.

The researchers found that of 111,707 initial primary prevention ICD implants that occurred during the study period, 25,145 (22.5 percent) were implanted in patients who didn't meet the guidelines. Of these, 9,257 were implanted in patients within 40 days of a heart attack (36.8 percent) and 15,604 were in patients with newly diagnosed heart failure (62.1 percent).

The risk of dying while in the hospital was significantly higher in patients who didn't meet the guidelines than in patients who did (0.57 percent vs. 0.18 percent). The risk of having any post-procedure complication was significantly higher in those who didn't meet the guidelines, at 3.23 percent, than in those who did, at 2.41 percent.

"Although the absolute difference in complications between the 2 groups is modest, these complications could have significant effects on patients' quality of life and health care use, including length of hospital stay and costs. Importantly, these complications resulted from procedures that were not clearly indicated in the first place. While a small risk of complications is acceptable when a procedure has been shown to improve outcomes, no risk is acceptable if a procedure has no demonstrated benefit," the authors wrote.

The risk of suffering any adverse event or death were significantly higher in patients who didn't meet the guidelines. The median (midpoint) length of hospital stay was significantly longer for patients who didn't meet the guidelines compared with patients who did (3 days vs. 1 day). Also, there was substantial variation across hospitals in the number of devices implanted in patients who didn't meet the guidelines.

There was no clear decrease in the rate of non-evidence-based ICDs over time.

"During this period of limited resources and due to the Centers for Medicare & Medicaid Services' emphasis on quality improvement by promoting evidence-based care, it is increasingly important to assess hospital performance and to provide feedback to hospitals about their outcomes and compliance with clinical guideline recommendations. Providing such feedback to hospitals has the potential to improve adherence to practice guidelines and eventually patient outcomes," the researchers wrote.

The study is published in the January 5 issue of the Journal of the American Medical Association.