Gurunanthan Palani

Prognostic value of regadenoson myocardial single-photon emission computed tomography in patients with different degrees of renal dysfunction

AIMS Patients with chronic kidney disease (CKD) have worse cardiovascular outcomes. The prognostic value of the new pharmacological stressor regadenoson (REG) in patients with varying levels of kidney function is not known (REG-SPECT). Furthermore, the impact of varying levels of kidney dysfunction on cardiac outcomes in patients undergoing REG-SPECT has not been defined. Our objective was to evaluate the prognostic value of regadenoson stress imaging in patients with different levels of kidney dysfunction. METHODS AND RESULTS We followed 1107 consecutive patients who underwent REG-SPECT for a mean duration of 1.8 ± 0.8 years. CKD was defined as estimated glomerular filtration rate (GFR) 60 mL/min/1.73 m(2). Kaplan-Meier survival analysis was performed to evaluate survival, free of major adverse cardiac events (MACE). CKD patients with GFR <60 (47% male, mean age 70 years) had a higher prevalence of cardiac risk factors and a history of coronary artery disease and were on significantly more cardiac medications (P < 0.001) than those with GFR >60. Patients with GFR <60 were significantly more likely to develop adverse cardiac outcomes including congestive heart failure (CHF) (P = 0.02), cardiac death (P < 0.001), all-cause death (P < 0.001), and MACE (P < 0.001) over the period of follow-up. Cardiac death increased with worsening levels of perfusion defects (SSS) across the entire spectrum of renal function (P < 0.001). GFR <60 was an independent predictor of MACE with a hazard ratio (HR) of 1.49 (95% CI: 1.06-2.08). The presence of transient ischaemic dilation (TID) was associated with an HR of 5.06 (95% CI: 1.43-17.90). CONCLUSIONS Renal function is a powerful risk predictor in patients undergoing REG-SPECT. REG-SPECT provides robust prognostication across the entire spectrum of renal function.

Regadenoson: review of its established role in myocardial perfusion imaging and emerging applications.

Myocardial perfusion imaging is a well-established noninvasive modality for the diagnosis and prognosis of coronary artery disease. The pharmacologic stress agents adenosine and dipyridamole are widely used in imaging studies, but cause undesirable side effects, like atrioventricular block and bronchospasm, due to their nonselective adenosine receptor activation. Furthermore, the mode of administration of these agents as a bolus infusion is less preferred. Regadenoson, an A2A adenosine receptor selective pharmacologic stress agent was approved in 2008 and is widely used instead of adenosine and dipyridamole. This article reviews regadenosons structure, mechanism of action, advantages over adenosine and dipyridamole, and its role in various patient populations undergoing stress perfusion imaging. Emerging applications where regadenoson could be of potential use are also explored.