Cardiac adrenergic nerve activity, evaluated using imaging with iodine-123 metaiodobenzylguanidine (MIBG), is associated with risk of sudden death in patients with mild-to-moderate heart failure. Cardiac adrenergic nerve activity, evaluated using imaging with iodine-123 metaiodobenzylguanidine (MIBG), is associated with risk of sudden death in patients with mild-to-moderate heart failure, according to a report in the October issue of Heart.

As a norepinephrine analog, MIBG can be used to estimate cardiac adrenergic nerve activity, the authors explain, and cardiac MIBG imaging has been shown to provide prognostic information in patients with congestive heart failure (CHF).

Dr. Hidetaka Kioka from Osaka General Medical Center, Osaka, Japan and associates performed cardiac MIBG imaging studies in 97 patients with mild-to-moderate CHF. About half the patients had normal MIBG washout rates (WR), and the other half had abnormally high WR, the investigators report.

During a mean follow-up of 65 months, 12 (25 per cent) patients in the abnormal WR group died suddenly, compared with two (four per cent) patients with normal WR, the report indicates.

The only independent predictor of sudden death and total mortality in multivariate analyses was MIBG WR.

"This result is consistent with the finding that increased sympathetic activity can modulate basic arrhythmia mechanisms of re-entry, automaticity, and triggered activity to provoke lethal arrhythmias," the researchers explain.

"To the best of our knowledge," they conclude, "this is the first study to show the usefulness of cardiac MIBG imaging in the prediction of sudden death in patients with mild-to-moderate CHF."

Heart 2007;93:1213-1218.