A strategy of symptom-limited exercise with regadenoson-as-needed for stress myocardial perfusion imaging: a randomized controlled trial.

BACKGROUND: Ambulatory patients with uncertain functional capacity may benefit from combined exercise and vasodilator stress protocols for myocardial perfusion imaging (MPI). The safety and MPI image quality with regadenoson administered during symptom-limited exercise have not been prospectively evaluated. METHODS AND RESULTS: A total of 140 patients (mean age 61 years, 48% female) referred for exercise with vasodilator stress MPI were randomized 2:1 to a strategy of exercise with regadenoson-as-necessary (Ex-Reg, n = 96) or dipyridamole with exercise (Dip-Ex, n = 44) after Duke Activity Status Index (DASI) scoring (median score 28 vs 24, P = .09). Ex-Reg subjects commenced treadmill exercise and regadenoson was administered only if the subject was unable to reach standard endpoints. Dip-Ex subjects received dipyridamole prior to symptom-limited exercise. Hemodynamics were recorded throughout. Subjects completed symptom questionnaires and MPI image quality was assessed by blinded read. Ex-Reg subjects were more likely to achieve ≥85% age-predicted maximum heart rate than Dip-Ex subjects (57% vs 32%, P < .01). Only 50% of subjects meeting inclusion criteria and randomized to Ex-Reg required regadenoson and none had symptomatic hemodynamic changes. Severe side effects or adverse events occurred in 16% of Ex-Reg and 24% of Dip-Ex subjects (P = .12). MPI image quality was "good" or "excellent" in 88% of Ex-Reg subjects and 86% of Dip-Ex subjects (P = .33). CONCLUSION: A strategy of exercise with regadenoson-as-needed for MPI offers similar safety and side effect profile with similar image quality compared to dipyridamole with exercise, with reduced pharmaceutical use.

Duration and type of therapy for diabetes: impact on cardiac risk stratification with stress electrocardiographic-gated SPECT myocardial perfusion imaging.

BACKGROUND: Stress electrocardiogram(ECG)-gated single photon emission computed tomography (SPECT) imaging is highly effective in risk stratification of diabetic patients for adverse cardiac events. While patients with diabetes are predisposed to a more aggressive progression of vascular disease, the impact of its duration and type of therapy on risk stratification are unknown. METHODS: From the Hartford Hospital Nuclear Cardiology clinical database, 886 diabetic patients who underwent exercise or pharmacologic stress ECG-gated SPECT were identified, with complete follow-up regarding the occurrence of adverse cardiac events and information regarding the duration of diabetes and the type of therapy (insulin vs oral medication only) at the time of testing. Images were interpreted using the American College of Cardiology/ASNC standard 17-segment scoring model. RESULTS: Of the 886 diabetic patients, 98 (11%) suffered cardiac death or non-fatal myocardial infarction during follow-up (2.5 ± 1.6 years). A receiver operator characteristics curve demonstrated that diabetes ≥10 years in duration provided the maximal sum of sensitivity and specificity for the prediction of adverse cardiac outcomes. Multivariate analysis identified the following as independent predictors of adverse outcome: Post-stress ejection fraction (EF) <40% (P = .001), age (P = .004), insulin therapy (P = .031), diabetes duration >10 years (P = .038), summed stress score (SSS) >8 (P = .046). For patients with an SSS >8, diabetes duration and type of therapy significantly enhanced risk stratification. Similar findings emerged for patients with a post-stress EF <40%. CONCLUSION: For diabetic patients undergoing stress ECG-gated SPECT myocardial perfusion imaging, disease duration and type of therapy provide independent and incremental prognostic information. Integration of these variables with this cardiovascular imaging technology significantly enhances cardiac risk stratification.