The Arrhythmogenicity of Theophylline: A Multivariate Analysis of Clinical Determinants

Objective to determine the relation of serum theophylline concentrations (STC) to the occurrence of cardiac arrhythmias in a population of hospitalized patients. Study Design A cross-sectional study of 100 patients receiving theophylline who had electrocardiograms at the time STC had been obtained. Categorization was based on STC without knowledge of clinical status: group 1 (25) had STC 20 (27.8±1.1) mg/L. Setting A university-affiliated teaching hospital. Results Two-thirds of the patients were receiving theophylline in an oral form, with a similar distribution found in all groups. Groups were not different with respect to age, clinical diagnoses, electrocardiographic patterns, arterial pH or gases, serum calcium, or treatment with β-agonists. Although fewer patients in group 1 were receiving steroids than those in the other groups, and serum potassium was lower in group 3 than in group 1 (4.0±0.6 vs 4.5±0.5 mEq/L, p Conclusion Theophylline causes tachycardia and serious arrhythmias even at STC considered to be therapeutic. Multifocal atrial tachycardia, an arrhythmia associated with use of this drug, may herald sudden cardiac death.