Remote ischemic preconditioning to reduce contrast-induced acute kidney injury in chronic kidney disease: a randomized controlled trial.

BACKGROUND: The impact of contrast-induced acute kidney injury (CI-AKI) on patients with chronic renal disease is well-known. Remote ischemic preconditioning (RIPC) is a non-invasive method that can reduce the risk of CI-AKI, but studies on RIPC have had different results. The aim of the present study was to assess the potential impact of RIPC on CI-AKI. METHODS: In a randomized, double blinded, controlled trial, 132 patients with chronic renal dysfunction (glomerular filtration rate < 60 mL/min/m2) who underwent coronary angiography or angioplasty received adequate hydration. RIPC was performed in 66 patients by applying an upper arm blood pressure cuff. The cuff was inflated four times for 5 min to 50 mmHg above the systolic blood pressure, followed by deflation for 5 min. In the control group, the blood pressure cuff was inflated only to 10 mmHg below the patient's diastolic blood pressure. The primary endpoint was an increase in serum cystatin C ≥ 10% from baseline to 48-72 h after exposure to the contrast. RESULTS: The primary endpoint was achieved in 48 (36.4%) patients (24 in each group). RIPC did not show any significant effect on the occurrence of the primary endpoint (P = 1). In addition, when the results were analyzed based on the Mehran risk score for subgroups of patients, RIPC did not reduce the occurrence of the primary endpoint (P = 0.97). CONCLUSIONS: In patients at moderate-to-high risk of developing CI-AKI when an adequate hydration protocol is performed, RIPC does not have an additive effect to prevent the occurrence of CI-AKI. TRIAL REGISTRATION: The clinical trial was registered on (Identification number IRCT2016050222935N2 , on December 19, 2016 as a retrospective IRCT).

Fractional Flow Reserve as a Standard of Reference for Ischemia Early After ST Elevation Myocardial Infarction.

BACKGROUND: The purpose of the present study was to assess the value of the fractional flow reserve (FFR) of the infarct-related artery (IRA) early after ST elevation myocardial infarction (STEMI) in detecting reversible ischemia. METHODS: Single photon emission computed tomography (SPECT) at rest and after dipyridamole stress, and within 24 hour FFR of the IRA was performed on 69 patients 3 to 7 days after STEMI. FFR was 0.80 or less in 61 (88.4%) of them. In these patients, percutaneous coronary intervention (PCI) was performed, and a second SPECT study was repeated within 14 days. RESULTS: SPECT showed reversible ischemia in 36 (59%) of these 61 patients, and converted to negative in 29 of them. Thus, the SPECT results of these 29 patients were defined as true positive before angioplasty and true negative after angioplasty. Considering the true-positive and true-negative SPECT results as the gold standard, the sensitivity, specificity, and positive and negative predictive values of the FFR of 0.80 or less compared to this gold standard were 96.7%, 100%, 100%, and 96.6%, respectively (ĸ = 0.97, P < 0.001). CONCLUSIONS: In the early phase after STEMI, the reliability of FFR to determine residual ischemia in the IRA is very high in those patients with true-positive SPECT before and true-negative SPECT after PCI.