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.