Postconditioning is protective in renal reperfusion injury only in male rats. A gender difference study

Effects of ischaemic postconditioning in aortic valve replacement: a multicenter randomized controlled trial

OBJECTIVES

The effect of ischaemic postconditioning (IPost) on postcardioplegic cardiac function is not known. We hypothesized that IPost was cardioprotective in adult patients undergoing elective aortic valve replacement.

METHODS

In a multicentre, prospective, randomized trial, patients (n = 209) were randomized to either a standard operation (controls) or postconditioning. Immediately before the cross-clamp was released, patients in the postconditioning group underwent 3 cycles of flow/non-flow (2 min each) of normothermic blood via the antegrade cardioplegia line. The primary end point was cardiac index. Secondary end points included additional haemodynamic measurements, biomarkers of cardiomyocyte injury, renal function parameters, intra- and postoperative arrhythmias and use of inotropic agents.

RESULTS

There was no significant difference between the groups regarding cardiac index [mean between-group difference, 95% confidence interval (CI), 0.11 (-0.1 to 0.3), P = 0.27]. Postconditioning had no effect on other haemodynamic parametres. There was no between-group difference regarding troponin T or creatine kinase MB. Postconditioning reduced the relative risk for arrhythmias by 45% (P = 0.03) when postoperative atrial fibrillation and intraoperative ventricular fibrillation were combined. There were no differences in patients with/without diabetes, patients above/below 70 years of age or between the centres. However, after postconditioning, the cardiac index [95% CI, 0.46 (0.2-0.7), P = 0.001], cardiac output (P < 0.001), mean arterial pressure (P < 0.001) and left ventricular stroke work index (P < 0.001) were higher in males compared to females.

CONCLUSIONS

IPost had no overall cardioprotective effects in patients undergoing aortic valve replacement but improved postoperative cardiac performance in men compared to women.

Scintigraphic evaluation of remote pre-conditioning protection against unilateral renal ischemia/reperfusion injury in rats: a longitudinal study

PURPOSE

To determine the role of remote perconditioning (RPeC) on renal function and histology in an animal model of unilateral renal ischemia and reperfusion (IR) injury.

METHODS

Rats were subjected to 60 min unilateral renal ischemia. RPeC protocol was the application of four cycles of 5 min IR of left femoral artery during renal ischemia. Assessments of histological changes and renal function were made 24 h, 1 week, or 3 weeks later. 99mTc-DMSA scan was performed using a small-animals SPECT system.

RESULTS

24-h reperfusion decreased the 99mTc-DMSA uptake in the left kidney compared to the intact kidney of control animals. RPeC group has higher uptake compared to the IR group. After 1 week and 3 weeks, uptakes were gradually increased in both groups and no differences were observed. Severe morphological changes in the ischemic kidneys of both groups were observed after 24 h which attenuated after 1 week and 3 weeks. Moreover, no differences in creatinine and BUN levels between IR-treated and intact animals were observed.

CONCLUSION

These data suggest that RPeC exerts a partially transient improvement in the renal function in the first day after reperfusion. However, long-term follow-up study showed no beneficial effects of RPeC. Moreover, noninvasive 99mTc-DMSA scan revealed a suitable tool in the follow-up evaluation of recovery process in the unilateral renal IR injury models.

Ischemic Postconditioning Before Percutaneous Coronary Intervention for Acute ST-Segment Elevation Myocardial Infarction Reduces Contrast-induced Nephropathy and Improves Long-term Prognosis

BACKGROUND AND AIMS

Contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) is one of the major adverse outcomes affecting the prognosis of patients with acute ST-segment elevation myocardial infarction (STEMI). Ischemic postconditioning prior to PCI (pre-PCI) in patients with STEMI is hypothesized to be protective against CIN after PCI.

METHODS

A total of 251 patients with STEMI were randomized into two groups: ischemic postconditioning group (n = 123, age, 61.1 ± 12.5 years) who underwent ischemic postconditioning prior to PCI; control group (n = 128; age, 64.1 ± 12.1 years) who underwent only PCI. Ischemic postconditioning was administered by three cycles of deflation and inflation of the balloon (1-min ischemia and 1-min reperfusion) starting 1 min after infarct-related artery (IRA) opening. Diagnostic criterion for CIN was: increase in serum creatinine level by ≥0.5 mg/dL or by ≥25% increase from preoperative level within 48 h of surgery. All patients were followed for 1 year for incidence of major cardiovascular events (MACE).

RESULTS

The incidence of postoperative CIN in the ischemic postconditioning group was 5.69% as compared to 14.06% in the control group (p <0.05). At one year, the MACE incidence in the ischemic postconditioning group was 7.32% as compared to 15.63% in the control group (p <0.05).

CONCLUSIONS

Pre-PCI ischemic postconditioning in STEMI patients significantly reduces the post-PCI incidence of CIN and improves long-term prognosis.

Preclinical Evidence for the Efficacy of Ischemic Postconditioning against Renal Ischemia-Reperfusion Injury, a Systematic Review and Meta-Analysis

BACKGROUND

Renal ischemia-reperfusion injury (IRI) is a major cause of kidney damage after e.g. renal surgery and transplantation. Ischemic postconditioning (IPoC) is a promising treatment strategy for renal IRI, but early clinical trials have not yet replicated the promising results found in animal studies.

METHOD

We present a systematic review, quality assessment and meta-analysis of the preclinical evidence for renal IPoC, and identify factors which modify its efficacy.

RESULTS

We identified 39 publications studying >250 control animals undergoing renal IRI only and >290 animals undergoing renal IRI and IPoC. Healthy, male rats undergoing warm ischemia were used in the vast majority of studies. Four studies applied remote IPoC, all others used local IPoC. Meta-analysis showed that both local and remote IPoC ameliorated renal damage after IRI for the outcome measures serum creatinine, blood urea nitrogen and renal histology. Subgroup analysis indicated that IPoC efficacy increased with the duration of index ischemia. Measures to reduce bias were insufficiently reported.

CONCLUSION

High efficacy of IPoC is observed in animal models, but factors pertaining to the internal and external validity of these studies may hamper the translation of IPoC to the clinical setting. The external validity of future animal studies should be increased by including females, comorbid animals, and transplantation models, in order to better inform clinical trial design. The severity of renal damage should be taken into account in the design and analysis of future clinical trials.