Cardiac risk assessment by gated single-photon emission computed tomography in asymptomatic end-stage renal disease patients at the start of dialysis

Abstract

Objectives: This study assessed the impact of cardiac risk assessment using gated single-photon emission computed tomography (SPECT) on cardiac events in end-stage renal disease (ESRD) patients.

Methods: We evaluated 215 asymptomatic patients who began dialysis between January 2005 and April 2009. Baseline electrocardiography and echocardiography were performed in all the patients. The subjects were stratified into low- and high-risk groups according to the baseline cardiac status, and gated SPECT was additionally recommended for the high-risk patients.

Results: The study population consisted of 50 low- and 165 high-risk patients undergoing SPECT. Among the high-risk patients, 75 (45.5%) showed perfusion defects on SPECT and their overall cardiac-event rate per person-year of follow-up was 15.0%, significantly higher than 4.5% in high-risk group without perfusion defect and 1.2% in low-risk group. The presence of perfusion defect was a significant independent predictor of adverse cardiac events [hazard ratio (HR) 2.11; 95% confidence interval (CI) 1.05-4.24; P = .035]. When gated SPECT was added to the clinical and the echocardiographic variables, the prognostic stratification significantly improved (P < .001). However, coronary revascularization was not associated with improved cardiac event-free survival (HR 0.62; 95% CI 0.26-1.52; P = .296).

Conclusions: Gated SPECT may provide additional prognostic information for cardiac risk stratification, particularly among high-risk patients starting dialysis.

Figure 1

Study flow diagram. From January 2005 to April 2009, 329 ESRD patients started dialysis and 215 included in our study. *High-risk group was defined as patients >50 years of age, diabetes >10 years, a prior history of CAD or an abnormal electrocardiogram (excluding LV hypertrophy and electrolyte imbalance), decreased LV ejection fraction (LVEF) <40% or regional wall motion abnormality (RWMA) on echocardiography, and having 2 or more traditional CAD risk factors. ESRD, end-stage renal disease; F/U, follow-up; ECG, electrocardiography; CAG, coronary angiography; CAD, coronary artery disease; CABG, coronary artery bypass graft; PCI, percutaneous coronary intervention

Figure 2

Kaplan-Meier estimates for the occurrence of cardiac events in low (n = 50)- and high (n = 165)-risk patients. Among high-risk patients, the presence of perfusion defect was closely associated with adverse cardiac outcomes (HR 3.16; 95% CI 1.65-6.04, P = .001) (A) and the presence of CAD significantly increased the risk of cardiac events (HR 1.94 95% CI 1.38-2.71, P < .001) (B)

Figure 3

Kaplan-Meier analysis of the cardiac event rate in high-risk patients with significant CAD. Revascularization therapy did not improve cardiac events-free survival (HR 0.62, 95% CI 0.26-1.52; P = .296)

Figure 4

Incremental prognostic value of SPECT over baseline (clinical only) and baseline plus 2D echocardiographic variables; upper global chi-square, lower ROC curve analysis