Orlando, Fla.--Myocardial scintigraphy can evaluate the integrity of the sympathetic nerves in patients with Class II and III heart failure (HF), according to research presented Tuesday at the 58th annual American College of Cardiology (ACC) late breaking clinical trials session.
"The Prognostic Significance of 123I-MIBG Myocardial Scintigraphy in HF Patients: Results From the Prospective Multicenter International ADMIRE-HF Trial" employed myocardial scintigraphy, which enables doctors to examine heart functions at the cellular level. 123I-meta-iodobenzylguanidine (123I-MIBG, which is marketed as AdreView from GE Healthcare) is not approved for cardiac imaging in the United States, though it has been in clinical use for two decades in the United States, Europe and Japan, according to the study's presenter Arnold F. Jacobson, MD, PhD, head of the Cardiac Center of Excellence at GE Healthcare.
ADMIRE-HF is the integration of two multicenter international Phase 3 trials designed to show the prognostic value of scintigraphy with the norepinephrine analog 123I-MIBG as a risk indicator for major cardiac events among 964 patients with heart failure. The composite endpoint was the time to the first occurrence of NYHA (New York Heart Association) HF class progression, potentially life-threatening arrhythmic event or cardiac death, as determined by an independent adjudication panel. Patients were followed for a maximum of two years.
"What this additional test provides is better discrimination in terms of the level of risk associated with these nerves, particularly in the very high-risk population," Jacobson said. "While this was not a treatment trial, it provides more information for clinicians who need to weigh their options for what therapies are available."
He reported that 25 percent of the patients experienced major adverse cardiac events during a mean follow-up of 18 months; first events were HF progression in 163 subjects--arrhythmic events in 51 and 24 cardiac deaths. An additional 29 cardiac deaths occurred as later events. Two year event-free survival was 85 percent in patients with H/M of at least 1.6 (heart/mediastinum ratio), compared with 63 percent for those with H/M less than 1.6.
Jacobson also reported that 51 cardiac deaths occurred in the low H/M group compared to two in the high H/M group and the negative predictive value of a high H/M for cardiac death over two years was 98.8 percent. He also noted that of the "21 percent of patients that had more normal cardiac uptake, the cardiac death rate was less than 1 percent a year over two years."
While the test itself has no effect on the patient's condition, Jacobson said that the data it provides "may contribute to the development of a more effective management strategy."
Based on their findings, Jacobson concluded that 123I-MIBG cardiac imaging has independent prognostic capability that is complementary to other commonly used markers such as left ventricular ejection fraction and BNP.
He also said that risk for HF mortality and arrhythmic events appears to show different tendencies in the H/M range 1through 1.6, with risk for the former decreasing with increasing ratios, while incidence of the latter appears to peak between 1.3 through 1.59.
GE provided the funding which supported the study.