[Use of high doses of atropine during dipyridamole echocardiography: safety and efficacy of the combined test].
BACKGROUND
Recent reports demonstrated an increased accuracy of dipyridamole echocardiography test with the intravenous infusion of 0.25 to 1 mg of atropine in 1-4 consecutive administrations at the end of the test. The effect of higher doses of atropine during dipyridamole echocardiography, potentially able to further increase heart rate and myocardial oxygen consumption, has not been evaluated. The aim of the study was to evaluate the effect of high doses of atropine during dipyridamole echocardiography and to investigate the possible pharmacological interference between dipyridamole and atropine.


METHODS
One-hundred consecutive patients (M = 81, F = 19; mean age 58 yrs) without inducible wall motion abnormalities at 14th minute of a high-dose (0.84 mg/Kg in 10') dipyridamole echocardiography test were studied. Seventy-five patients referred to the test in pharmacological wash-out were randomly divided in three groups: 25 patients (Group 1) received 10 mcg/Kg of atropine in 60"; 25 patients (Group 2) received 15 mcg/Kg of atropine in 120"; 25 patients (Group 3) received 20 mcg/Kg of atropine in 120"; moreover, 25 patients with a full-dose oral beta-blocker therapy (Group 4) received 20 mcg/Kg of atropine in 120". Atropine was infused during the 15th and 16th minute of the test. Heart rate (HR) changes and new wall motion abnormalities induced by atropine were considered and compared for each Group. In 60 patients (15 randomly selected from each Group) the effect on mean HR and R-R interval (msec) of the same dose of atropine infused during dipyridamole echocardiography was evaluated in resting conditions 24 hours apart.


RESULTS
The dipyridamole-atropine test was well tolerated and accomplished in all patients. HR increased significantly in all Groups of patients in comparison with pre-atropine HR values (Group 1: +14 +/- 8 b/m', p < 0.0001; Group 2: +19 +/- 8 b/m', p < 0.0001; Group 3: +22 +/- 9 b/m', p < 0.0001; Group 4: +19 +/- 8 b/m', p < 0.0001; Groups 2, 4 vs Group 1: p = 0.03, Group 3 vs Group 1: p = 0.002). No patients in Group 1 (0%), 3 patients in Groups 2 and 3 (12%), and 5 patients in Group 4 (20%) showed new wall motion abnormalities after atropine infusion (Group 4 vs Group 1: p = 0.06). Effects of atropine on HR and mean R-R interval were significantly more pronounced in resting conditions than during dipyridamole test (HR: +25 +/- 11 vs +18 +/- 9 b/m', p < 0.001; R-R: -256 +/- 122 vs -127 +/- 68 msec, p < 0.0001).


CONCLUSIONS
High doses of atropine during dipyridamole echocardiography test are safe and more effective for induction of new wall motion abnormalities than usual doses, particularly in patients tacking beta-blockers. The likelihood of an antagonistic mechanism between atropine and endogenous, dipyridamole-induced adenosine on sinus node is supported from our results.
Coletta
C
C
Cardiologia, Ospedale S. Spirito, Roma.
Greco
G
G
Galati
A
A
Ricci
R
R
Ceci
V
V
D000284:Administration, Oral; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000175:diagnosis; D015906:Angioplasty, Balloon, Coronary; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D001285:Atropine / Q000008:administration & dosage; D017023:Coronary Angiography; D004176:Dipyridamole; D004452:Echocardiography; D005069:Evaluation Studies as Topic; D005260:Female; D006339:Heart Rate; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis; D009204:Myocardial Revascularization; D013997:Time Factors; D014665:Vasodilator Agents
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D014665:Vasodilator Agents; D004176:Dipyridamole; D001285:Atropine
Impiego di alte dosi di atropina in corso di eco-dipiridamolo: tollerabilità ed efficacia del test combinato.