Value of hepatic computerized tomographic scanning during amiodarone therapy

Area of Science:

• Pharmacology
• Radiology
• Cardiology

Background:

• Amiodarone therapy monitoring is challenging due to poor correlation between plasma drug levels and clinical outcomes.
• Tissue drug levels are better indicators of efficacy and toxicity but are difficult to measure directly.

Purpose of the Study:

• To investigate the utility of abdominal CT scanning for assessing amiodarone and desethylamiodarone (DA) deposition in the liver.
• To explore the correlation between liver drug deposition, plasma drug levels, and QTc intervals.

Main Methods:

• Abdominal CT scans were performed on ten patients undergoing chronic amiodarone therapy.
• Liver and spleen CT densities were measured, and liver drug levels were estimated using a calibration curve with inorganic iodide.
• Correlations were analyzed between liver CT density, plasma amiodarone and DA levels, and QTc intervals.

Main Results:

• Increased liver CT density (68–94 CT units) was observed in 6 out of 10 patients.
• Increased liver/spleen relative CT density (1.4–2.0) was noted in 5 patients.
• Estimated liver drug levels reached up to 3 g/kg.
• Liver CT density correlated significantly with plasma DA levels (r=0.65, p<0.05) but not amiodarone (r=0.55, p<0.1).
• No significant correlation was found between liver CT density and QTc intervals.

Conclusions:

• Abdominal CT scanning provides an indirect estimate of liver amiodarone and DA deposition.
• This imaging technique may offer a valuable tool for monitoring amiodarone therapy, particularly when plasma levels are not indicative of tissue drug burden.
• Further research could validate CT scanning as a surrogate marker for guiding antiarrhythmic treatment decisions.