Follow-up of troponin I concentration in dogs with atrioventricular block and dual-chamber pacing in a case-matched study.

BACKGROUND: Increased cardiac troponin I (cTnI) concentration has been reported in dogs with atrioventricular (AV) block before and shortly following pacemaker implantation. The role of AV dyssynchrony, age, or concurrent cardiac disease on cTnI concentration remains unknown.

OBJECTIVES: To investigate change in cTnI concentration following dual-chamber pacemaker implantation on short- and long-term follow-up and to compare cTnI values to a case-matched control group.

ANIMALS: Thirty-eight client-owned dogs with permanent AV block and 38 matched control dogs.

METHODS: Retrospective review of medical records. Pacemaker group consisted of dogs with AV block and dual-chamber pacing. Control group matched the study population in age and cardiac disease. cTnI was compared between pacemaker and control group on short- and long-term follow-up. Different lead types and influence of arrhythmia on cTnI were tested.

RESULTS: cTnI was high at presentation (median 0.66 ng/ml; range 0.03-18.6) and showed a significant reduction over time after pacemaker implantation (p < 0.0001). Median cTnI values were significantly different between pacemaker and control group on short-term (p = 0.0004; 0.11 ng/ml, range 0.03-1.36 versus 0.06 ng/ml, range 0.03-0.46), but not on long-term follow-up (p = 0.0547; 0.14 ng/ml, range 0.03-0.73 versus 0.07 ng/ml, range 0.03-0.46). Lead type and severity of arrhythmia did not show a significant correlation to cTnI concentration.

CONCLUSIONS: On long-term follow-up, cTnI remained mildly elevated in some of the pacemaker dogs but was not significantly different to the matched control group.