DRUG INDUCED BRADYCARDIA

OUTCOME OF PATIENTS WITH BRADYCARDIA AFTER DISCONTINUATION OF RATE SLOWING DRUGS IN TERMS OF FREQUENCY OF PERSISTENT BRADYCARDIA.

Abstract

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.