Dobutamine-Atropine Stress Echo. New Protocol in Patients Treated with β-Blockers

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Abstract

Background

Dobutamine stress echo became a standard technique to evoke myocardial ischemia. Atropine addition at the end of dobutamine infusion was associated with a significant increase in the chronotropic response, without modifying its safety profile. Anyway, the addition of atropine at the end of the last stage of dobutamine infusion makes the study longer and creates an abrupt increase in heart rate and double product.

Objective

To assess the efficacy of a new protocol of early atropine infusion in patients treated with (3-blockers who were submitted to a dobutamine stress echo study.

Material and methods

One hundred and fifty patients treated with (β--blockers were submitted to a dobutamine stress echo study. Patients had a heart rate at rest <_ 65 beats per minute (bpm). Patients in group A (n =75) were assigned to a conventional protocol with the addition of atropine at the end of the last stage of dobutamine infusion, and subjects in group B(n = 75) were treated with the early addition of atropine at the beginning of each stage of dobutamine infusion.

Results

Mean age was 57.6 years old (group A) and 66.6years old (groupB).Baseline characteristics, adverse events and positive tests for ischemia were comparable in both groups. All patients in group Are ached the last stage of the test while 28% patients in group B finished the test in an early stage. Both groups had similar heart rate values at the maximum dosis(115 versus 119 bpm, groups A and B, respectively). There were significant differences in the peak heart rate during the first three stages and during recovery. Patients in group A showed a sud-den heart rate increase with the addition of atropine while in group B the increase of heart rate was progressive (58.66 and 74 versus 74.91 and 108 bpm respectively, p < 0.001). Duration of the test was significant longer in group A (21.9 min versus 16.8 min, p < 0.001 for groups A and B, respectively). Dobutamine and atropine infusion doses were higher in group A (40 y versus 36 y for dobutamine, p <0.001; and 0.96 versus 0.89 for atropine, p < 0.001).

Conclusions

The new protocol of early addition of atropine lead to a progressive increase of the heart rate from the beginning of the test, a lower heart rate during recovery and a decrease in examination time, without altering the safety of the test. It could be a more adequate strategy in patients receiving (β--blockers and scheduled for dobutamine stress echo.