Complete heart block in chronic chloroquine poisoning

Area of Science:

• Cardiology
• Clinical Toxicology
• Pharmacology

Background:

• Chloroquine is an antimalarial and antirheumatic drug.
• Drug abuse can lead to unexpected toxic effects.
• Cardiac complications are known but rare side effects of chloroquine.

Observation:

• A patient presented with complete heart block of recent onset.
• The patient had a history of chronic chloroquine abuse.
• Blood analysis revealed significantly elevated chloroquine levels.

Findings:

• Total blood chloroquine concentration was more than double that of patients on therapeutic doses.
• Proportionally higher levels of chloroquine basic metabolites were observed.
• These findings suggest a causal link between chronic chloroquine abuse and complete heart block.

Implications:

• Highlights the potential cardiotoxicity of chronic chloroquine abuse.
• Underscores the importance of monitoring drug levels in cases of substance abuse.
• Suggests complete heart block as a potential adverse event in chronic chloroquine misuse.