Safety and feasibility of atropine added to submaximal exercise stress testing with Tl-201 SPECT for the diagnosis of myocardial ischemia.

Background: We aimed to assess whether atropine administration is safe and feasible in patients unable to reach the minimal heart rate (HR) required (80% of age-predicted HR) in myocardial scintigraphic studies after exercise stress testing (EST).

Methods And Results: We studied 108 patients who underwent myocardial perfusion scintigraphy after EST; 0.5 mg of atropine was administered to those showing signs of fatigue before reaching minimal HR (group A, n = 44). The scintigraphic results for group A were compared with those of patients who spontaneously achieved minimal HR (group B, n = 64). Coronary angiographic results, if available, and clinical follow-up were also compared. In group A, atropine increased HR by 13.7 +/- 7.4 beats/min. The percentage of maximal age-related HR achieved was 83.3% +/- 7.5%; 74% achieved minimal HR. No major adverse effects occurred. When groups A and B were compared, baseline and peak HR, rate pressure product, and maximal metabolic equivalents achieved were higher in group B. There were no differences in number of perfusion studies positive for ischemia (group A, 26/44, and group B, 30/64; P =.2), coronary lesions, or clinical follow-up.

Conclusions: Atropine added to EST in patients who cannot achieve their 80% age-related HR is a safe and potentially useful method for myocardial perfusion studies.