Prognostic significance of ischemic electrocardiographic changes with regadenoson stress myocardial perfusion imaging.

BACKGROUND: In patients undergoing regadenoson SPECT myocardial perfusion imaging (MPI), the prognostic value of ischemic ST-segment depression (ST↓) and the optimal ST↓ threshold have not been studied. METHODS: A retrospective cohort study of consecutive patients referred for regadenoson stress MPI was conducted. Patients with uninterpretable ECG were excluded. Two diagnostic thresholds of horizontal or downsloping ST↓ were studied, ≥ 0.5 mm and ≥ 1.0 mm. The primary endpoint was the composite major adverse cardiac events (MACE) of cardiac death, myocardial infarction, or coronary revascularization. RESULTS: Among 8615 subjects (mean age 62 ± 13 years; 55% women), 89 (1.0%) had ST↓ ≥ 1.0 mm and 133 (1.5%) had ST↓ ≥ 0.5 mm. Regadenoson-induced ST↓ was more common in women (P < .001). Mean follow-up was 2.5 ± 2.2 years. After multivariate adjustment, ST↓ ≥ 1.0 mm was associated with a non-significant increase in MACE risk (P = .069), irrespective to whether MPI was abnormal (P = .162) or normal (P = .214). Ischemic ST↓ ≥ 0.5 mm was independently associated with MACE in the entire cohort (HR 2.14; CI 1.38-3.32; P = .001), whether MPI is normal (HR 2.07; CI 1.07-4.04; P = .032) or abnormal (HR 2.24; CI 1.23-4.00; P = .007), after adjusting for clinical and imaging covariates. An ST↓ threshold of ≥ 0.5 mm provided greater incremental prognostic value beyond clinical and imaging parameters (Δχ2 = 12.78; P < .001) than ≥ 1.0 mm threshold (Δχ2 = 3.72; P = .093). CONCLUSION: Regadenoson-induced ischemic ST↓ is more common in women and it provides a modest independent prognostic value beyond MPI and clinical parameters. ST↓ ≥ 0.5 mm is a better threshold than ≥ 1.0 mm to define ECG evidence for regadenoson-induced myocardial ischemia.

The prognostic value of heart rate response during vasodilator stress myocardial perfusion imaging in patients with end-stage renal disease undergoing renal transplantation.

BACKGROUND: In asymptomatic end-stage renal disease (ESRD) patients undergoing vasodilator stress myocardial perfusion imaging (MPI) prior to renal transplantation (RT), the impact of pre-transplant heart rate response (HRR) to vasodilator stress on post-RT outcomes is unknown. METHODS: We analyzed a retrospective cohort of asymptomatic patients with ESRD who underwent a vasodilator stress SPECT-MPI and subsequently received RT. Blunted HRR was defined as HRR <28% for regadenoson stress and <20% for adenosine stress. The primary endpoint was major adverse cardiac events (MACE), defined as cardiac death or myocardial infarction. Clinical risk was assessed using the sum of risk factors set forth by the AHA/ACCF consensus statement on the assessment of RT candidates. RESULTS: Among 352 subjects, 140 had an abnormal pre-transplant HRR. During a mean follow-up of 3.2 ± 2.0 years, 85 (24%) MACEs were observed. Blunted HRR was associated with increased MACE risk (hazard ratio 1.72; 95% confidence interval 1.12-2.63, P = 0.013), and remained significant after adjustment for gender, sum of AHA/ACCF risk factors, summed stress score, baseline heart rate, and ß-blocker use. HRR was predictive of MACE in patients with normal MPI and irrespective of clinical risk. Blunted HRR was associated with a significant increase in post-operative (30-day) MACE risk (17.9% vs 8.5%; P = 0.009). CONCLUSION: In asymptomatic ESRD patients being evaluated for RT, a blunted pre-transplant HRR was predictive of post-RT MACE. HRR may be a valuable tool in the risk assessment of RT candidates.

Validation of a clinical pathway to assess asymptomatic renal transplant candidates using myocardial perfusion imaging.

BACKGROUND: An AHA/ACCF scientific statement proposed 8 risk factors to assess the need for noninvasive coronary artery disease (CAD) surveillance in asymptomatic patients undergoing evaluation for kidney transplantation. The clinical application of these risk factors and the role of noninvasive testing in this context have not been defined. METHODS AND RESULTS: We retrospectively followed a cohort of 581 consecutive kidney transplant recipients of whom 401 had pre-transplant radionuclide myocardial perfusion imaging (MPI) and 90 had pre-transplant coronary angiography. The sum of pre-transplant AHA/ACCF risk factors (age >60 years, hypertension, diabetes, cardiovascular disease, dyslipidemia, smoking, dialysis >1 year, left ventricular hypertrophy) was calculated. MPI scans were analyzed by a "blinded" reader. Patients were followed for a mean of 3.7 ± 2.3 years post-transplant for major adverse cardiac events (MACE), defined as cardiac death or non-fatal myocardial infarction. The sum of risk factors was associated with modest discriminatory capacity for obstructive angiographic CAD (area under the curve [AUC], 0.70; P = 0.004), 30-day post-operative MACE (AUC, 0.60; P = 0.036), and long-term MACE (AUC, 0.63; P < 0.001). A threshold of ≥3 risk factors was optimal for identifying patients at risk. MPI provided incremental predictive value for obstructive CAD (P = 0.02) and long-term MACE (P = 0.04) but not post-operative MACE (P = 0.56). MPI was best predictive of long-term MACE in intermediate risk (3-4 risk factors) patients. CONCLUSIONS: Asymptomatic kidney transplant candidates with ≥3 AHA/ACCF risk factors are at increased cardiac risk, and should be considered for noninvasive CAD surveillance. Intermediate risk patients (3-4 factors) benefit the most from pre-transplant MPI to define long-term MACE risk.