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Sinus Bradycardia in Habitual Cocaine Users
Sona M Franklin1, Sudarone Thihalolipavan2, John M Fontaine1
1Electrophysiology Section, Division of Cardiology, Drexel University College of Medicine, Philadelphia, Pennsylvania.
The American Journal of Cardiology
|March 26, 2017
Summary
Habitual cocaine use significantly increases the risk of sinus bradycardia (SB), a slow heart rate, contrary to its usual stimulant effects. This suggests cocaine may desensitize beta-adrenergic receptors.
Area of Science:
- Cardiology
- Pharmacology
- Toxicology
Background:
- Cocaine typically causes adrenergic stimulation, leading to increased heart rate.
- Sinus bradycardia (SB), a slow heart rate, is an uncommon and paradoxical effect of cocaine use.
- Limited research exists on the prevalence and mechanisms of cocaine-induced SB.
Purpose of the Study:
- To determine the prevalence of SB in habitual cocaine users.
- To investigate potential mechanisms linking cocaine use to SB.
- To compare SB rates between cocaine users and non-users.
Main Methods:
- Retrospective analysis of 162 habitual cocaine users and matched controls.
- Defined SB as heart rate <60 beats/min.
- Used propensity score-matching to control for confounding variables.
- Excluded patients with pre-existing bradycardia, hypothyroidism, or beta-blocker use.
Main Results:
- SB prevalence was 27% in cocaine users versus 6% in non-users (p=0.0001).
- After propensity score-matching, SB was found in 23% of cocaine users and 5% of non-users (p=0.0001).
- Habitual cocaine use independently predicted SB, increasing risk sevenfold (95% CI 2.52 to 19.74, p=0.0002).
Conclusions:
- Habitual cocaine use is a strong predictor of SB, irrespective of recent use.
- Cocaine-induced beta-adrenergic receptor desensitization is a potential mechanism for SB.
- No symptomatic SB or need for pacemaker therapy was observed.