Usefulness of atropine in patients with chronotropic incompetence and poor exercise capacity during treadmill stress testing

BackgroundAtropine, an anticholinergic agent, has been shown to increase heart rate and enhance the sensitivity of dobutamine stress echocardiography in the detection of CAD in patients with chronotropic incompetence; however, the addition of atropine to exercise stress testing EST, in these types of patients has not been well studied previously.ObjectiveInvestigating the usefulness and accuracy of atropine in decreasing the number of inconclusive results of EST in patients with chronotropic incompetence and poor exercise capacity.MethodsThirty patients (16 males and 14 females with the age range of 40:73 years with mean of 55 ± 8) out of 180 patients who preformed EST were chosen as having chronotropic incompetence or poor exercise capacity by Borg scale. Atropine was administered during the exercise phase in doses of 0.5 mg per minute until test conclusion or the maximum dose of 2 mg was reached. All patients were subjected to stress myocardial perfusion imaging SMPI to confirm accuracy.ResultsConclusive test results were achieved in 29 patients (97%). Heart rate and blood pressure were markedly increased with statically highly significant difference (P value <0.001), patients on b-blocker treatment had lower maximum heart rate compared to other patients with significant difference. Twenty-three (79%) patients had negative test results and six (21%) patients had positive test results, and if compared to SMPT results, EST was considered better positive than negative test, with higher specificity than sensitivity and accuracy.ConclusionsAtropine injection during EST significantly reduced the inconclusive test results in patients with chronotropic incompetence and poor exercise capacity.