Munir Ahmad, Muhammad Yasir, Sehar Fatima.
Drug Induced Bradycardia; Outcome of patients with Bradycardia After Discontinuation of Rate Slowing Drugs in Terms of Frequency of Persistent Bradycardia.
Professional Med J Jan ;25(6):908-13.

Background: Bradycardia in patients on rate slowing drugs i.e. beta blockers, digoxin and non dihydropyridine calcium channel blockers is common after discontinuation of rate slowing drugs. Bradycardia persists in majority of patients, so bradycardia is not truly drug induced but due to underlying conduction system disease. Objectives: To determine the outcome in patients with bradycardia after discontinuation of rate slowing drugs in terms of frequency of persistent bradycardia. Study Design: Descriptive cross-sectional. Place and Duration of Study: Cardiology Department, Faisalabad Institute of Cardiology, Faisalabad, from September 2015 to March, 2016. Methodology: After written informed consent 95 patients who fulfilled the inclusion and exclusion criteria were selected for this study. Patients with bradycardia (heart rate less than 60 beats per minute) identified by pulse and electrocardiography (ECG) were admitted and culprit drug was discontinued. All admitted patients were followed everyday by doing ECG and counting pulse twice. Patients, in whom bradycardia resolved, were discharged. Patients were monitored for persistent bradycardia after discontinuation of culprit drug for 5 days. Results: Out of 95 patients 46 (48%) were male and 49 (52%) female, age range was 25-85 years with mean age 61±11 years. Heart rate ranged 25-45 beats per minute with mean value of 31.28± 6.08, 72 (75.8%) patients were on beta blockers, 19 (20%) on calcium channel blockers and 4 (4.2%) patients were on digoxin. 73 (76.80%) patients had 30 AV block, 19 (20%) 20 AV block while 3 (3.20%) had sinus bradycardia. Bradycardia persisted in 69 (72.60%) patients out of which 32 (69.6%) were male and 37(75.5%) female. Bradycardia resolved in 26 (27.40%) patients in which 14 (30.4%) were male and 12(24.5%) were female. Conclusion: Persistent bradycardia is common in patients with drug induced bradycardia. Such bradycardia is not truly drug induced but is related to unmasking of subclinical conduction system disease by rate lowering drugs like beta blockers, calcium channel blockers and digoxin.

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