HRS: Off-guideline ICD use for primary prevention may not cause harm
BOSTON—Despite recent studies that question the "inappropriate use" of implantable cardioverter-defibrillators (ICDs) in primary prevention, the large OMNI registry, presented May 11 at the 33rd annual scientific sessions of the Heart Rhythm Society (HRS), found that patients who received ICD implants in a non-evidence based manner experienced similar therapeutic benefit and outcomes to those who received evidence-based treatments.

Also, even though the 2009 highly publicized Al-Khatib et al study released in the Journal of the American Medical Association (JAMA) demonstrated that 20 percent of patients who received ICDs did not meet evidence-based guidelines for the devices, this real-world registry found the number was closer to one in 10.

“The study by Al-Khatib et al was well-designed and executed, but it was missing detailed information about the decision-making process in choosing to implant a defibrillator,” principal investigator Christian E. Machado, MD, director of the Cardiac Electrophysiology and Cardiac Rhythm Management Device Clinic at Providence Hospital in Detroit, told Cardiovascular Business. “Because patient-centric decision making cannot be captured with guidelines or a widespread data analysis, the resulting spin on the results of Al-Khatib et al’s study was quite negative for the field of electrophysiology. Thus, many of us were unhappy with the interpretation those findings, as well as the media coverage.”

In response, he and his colleagues performed a retrospective analysis of the OMNI registry to isolate the primary prevention (PP) ICD cohort, using MADIT II and SCD-HeFT criteria, while excluding patients with cardiac resynchronization therapy-defibrillators. “Our idea was to re-examine this patient population from a real-world registry point of view in a variety of clinical settings to see if we found the same rate of ‘inappropriateness’ and most importantly, to assess the outcomes of these patients,” Machado said.

The researchers established the measured endpoints of time to first appropriate therapy for adjudicated ventricular tachycardia/ventricular fibrillation, death from any cause and time to first inappropriate therapy. They identified non-evidence based (NEB) patients if the implant occurred within one month of MI, within three months from a diagnosis of non-ischemic dilated cardiomyopathy or in the setting of New York Heart Association IV symptoms.

Of the 1,412 ICD patients assessed in OMNI, Machado and colleagues identified 570 PP ICD patients, with 10.4 percent of them receiving NEB treatment. Speaking of the disparity of findings with the Al-Khatib et al findings, Machado acknowledged that the slight difference in the definition may have had some impact.

“Either way, our findings were statistically significantly lower than their results related to outside the guideline implantations,” he said. Also, in OMNI, NEB patients were younger than evidence-based (mean age, 61 vs. 67 years) and more likely non-ischemic (56 percent vs. 15 percent).

Over an average follow-up of 3.3 years, 156 PP patients received appropriate ICD therapy and 119 patients died. “This means that the off-guideline/on-guideline patients were receiving very similar therapies for very similar, life-threatening arrhythmias with very similar, positive results,” said Machado. “Because some people question the use of appropriate shocks as an endpoint, we also examined mortality, and we learned that these patients are living as long as patients who receive ICDs according to a strict interpretation of the guidelines.”

As compared with the EB group, the researchers reported that the NEB group experienced similar outcomes in time to first appropriate ICD therapy (Hazard Ratio [HR], 0.89), risk of death (HR, 1.20) and time to first inappropriate ICD therapy (HR, 1.19).

“We feel this study is a valuable surrogate of real-world clinical practice, where clinical needs require real medical decisions,” Machado said. “Additionally, it continues to emphasize the importance of the physician-patient relationship. While guidelines are important, our ultimate mission is to save our patient’s life and know we are giving them a fighting chance. We believe this study provides that knowledge.”

In a statement accompanying the release of the OMNI registry, the HRS said it has “openly emphasized—as did the JAMA article—that ‘the ultimate judgment of the care of a particular patient must be made by the physician and the patient in light of all of the circumstances presented by the patient. There are circumstances in which deviations from these guidelines are appropriate.’”