ASNC: AdreView falls short of risk stratifying for arrhythmic events
PHILADELPHIA—Data from the ADMIRE-HFX study did not yield a significant hazard ratio for 123I-mIBG (AdreView, GE Healthcare) SPECT to define risk of arrhythmic events in patients with heart failure, according to a late-breaking clinical trial presented at the 2010 annual American Society of Nuclear Cardiology meeting (ASNC).

The ADMIRE-HFX study is an extension of the ADMIRE-HF trial. In the original trial, researchers studied nearly 1,000 heart failure patients (class II/III) with left ventricular ejection fraction less than 35 percent in an effort to risk stratify for cardiac events.

The ADMIRE-HFX study specifically focused on strengthening the prediction of arrhythmic events and cardiac death, and followed up patients even further, for a median of 24 months, said lead investigator Denis Agostini, MD, from CHU Cote de Nacre in Caen, France.

Patients underwent planar and SPECT imaging with the investigational radiotracer. Less AdreView uptake indicates more damage to the sympathetic nerves, which is associated with progressive deterioration and remodeling of the myocardium, inexorable decline in LV function and worsening symptoms.

Researchers quantified cardiac 123I-mIBG uptake as the heart/mediastinum ratio (H/M) at four hours on anterior planar images (H/Mp) of all subjects and SPECT images (H/Ms) of 928 subjects. An H/M ratio of 1.60 or greater is associated with less risk of a cardiac event.

The composite endpoint was time to first occurrence of left ventricular assist device (LVAD) insertion or heart transplant, a surrogate for cardiac death; potentially life-threatening arrhythmic event, including appropriate ICD discharge; or cardiac death.

Among the subjects with both H/Mp and H/Ms, 133 had cardiac events, including transplants (six), LVAD implantations (three), arrhythmic events (69) and cardiac deaths (56). Eight subjects with non-fatal arrhythmic events subsequently had cardiac death. The total number of patients with arrhythmic events—both non-fatal and sudden death—was 96.

Researchers did not find a significant hazard ratio (HR) for defining arrhythmic event risk (HR 0.38 for H/Mp and 0.90 for H/Ms). They did, however, find that an H/Mp of 1.60 or greater was associated with preserved sympathetic innervation, which equated to a very low risk of cardiac death over two years. HRs for cardiac death were 0.075 for H/Mp and 0.48 for H/Ms.

The two-year cardiac and all-cause mortality rates in the total population were 7.8 percent and 11.6 percent, respectively.

Among 92 patients with H/Mp less than 1.20, the two-year cardiac and all-cause mortality rates were 16.7 percent and 23.4 percent, respectively, compared with 3.6 percent and 6.2 percent for H/Mp from 1.60 to 1.69 (94 patients), 1.9 percent and 3.6 percent for H/Mp from 1.70 to 1.79 (60 patients) and 0 percent and 0 percent for H/Mp greater than 1.80 (47 patients).

HRs for all-cause mortality were 0.067 H/Mp and 0.53 H/Ms, and for the composite endpoint, they were 0.31 H/Mp and 0.77 H/Ms.

Agostini said that the prediction of events was the same in men and women. He concluded that preserved sympathetic innervation is associated with low risk of cardiac death at two years as shown by an H/M of greater than 1.60.