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Gare et al. (1) report no advantage of dopamine over “adequate hydration” in patients with mild to moderate renal insufficiency undergoing coronary angiography. The absence of a clinically important effect is no surprise, for dopamine (2 mg/kg/min) would not be a sufficient vasodilator to counteract such a potent renal afferent arteriole vasoconstrictor as intrarenal adenosine. The kidney responds to contrast media-induced osmotic stress with afferent arteriolar vasoconstriction. This tubuloglomerular feedback response is largely mediated by adenosine, a mechanism that has been confirmed by both animal and clinical studies (2–5). In our randomized and blinded studies, the magnitude of adenosine release and depression of creatinine clearance was proportional to the osmolality of the contrast agent, essentially a dose-response relation (2). It is attenuated by the adenosine receptor blocker theophylline (3–5).
When pretreated with long-acting theophylline in addition to hydration with D5W or half-normal saline, patients with moderate renal dysfunction (creatinine ≤2.0 mg/dl) are reliably protected from the nephrotoxic effects of contrast media (3–5). We currently prescribe Theodur (3 mg/kg) orally the night before and b.i.d. the day of angiography. It is critical that theophylline be administered before contrast injection, but prolonged treatment after angiography is unnecessary.
Theophylline prophylaxis to attenuate contrast-media nephrotoxicity has not been adopted by cardiologists, perhaps because the studies appeared in journals they do not normally read. Theophylline prophylaxis is effective, safe, and inexpensive. In view of the magnitude of the clinical problem of contrast-media nephrotoxicity, we wish to bring this therapeutic strategy to the attention of the readers of JACC.
- American College of Cardiology