A Randomized Controlled Trial of Intra-Aortic Adenosine Infusion Before Release of the Aortic Cross-Clamp During Coronary Artery Bypass Surgery

Outcomes of Coronary Artery Bypass Graft Surgery in Africa: A Systematic Review and Meta-Analysis

Coronary artery bypass graft (CABG) surgery has been in practice for many decades, and it is one of the most commonly performed cardiac surgeries worldwide. While there are several studies reporting data on perioperative outcomes following CABG in developed countries, there is a staggering paucity of data and evidence reporting the outcomes in developing areas such as Africa. Thus, it is important to study the practice and outcome of CABG in Africa to establish its clinical efficacy and safety in this region and identify factors that might be limiting its practice. The overall aim of this study is to identify all relevant clinical data on CABG in Africa and report on the perioperative outcomes and practice of CABG in the African population. Electronic search was performed using three online databases, PubMed, African Journal Online, and Research Gate, from inception to June 2023. The preferred reporting items for systematic reviews and meta-analysis (PRISMA) guideline was utilised for this study. Relevant studies fulfilling predefined eligibility criteria were included in the study. Intraoperative details, such as the number of grafts performed, operative, bypass, and cross-clamp time, were reported. The primary endpoint assessed were early mortality and overall mortality. The secondary endpoints included length of hospital stay, intensive care unit stay, and postoperative complications, such as renal impairment, atrial fibrillation, and surgical site infection. The data were pooled together and meta-analyzed using a random effect model for proportions and mean for meta-analysis with R software (version 4.3.1 (2023-06-16); R Development Core Team, Vienna, Austria). This systematic review identified 42 studies that fulfilled the study eligibility criteria, including 21 randomised controlled trials, 20 observational studies, and one cross-sectional study. Only four out of the 54 countries in Africa had studies carried out that met the criteria for this review; they included Algeria, Egypt, Nigeria, and South Africa, with a majority from Egypt. Meta-analysis reported a pooled early mortality and pooled overall mortality of 3.51% and 3.73%, respectively, for the total cohort of patients. The result of this meta-analysis suggests that mortality outcomes following CABG in Africa are relatively higher than those in developed nations. Several issues, such as lack of financial resources and poor infrastructure, continue to hinder the optimal practice of CABG procedures in many parts of Africa. Further studies focused on finding factors associated with outcomes following CABG should be done. Though there were a few limitations to the study largely from a lack of data from several regions and countries in Africa, the result from this meta-analysis can serve as a benchmark for future studies until more relevant data are reported.

High-dose adenosine versus saline-induced cardioplegic arrest in coronary artery bypass grafting: A randomized double-blind clinical feasibility trial

BACKGROUND AND OBJECTIVE

In this clinical trial, we evaluated if a short-acting nucleoside, adenosine, as a high-dose bolus injection with blood cardioplegia induces faster arrest and provides better myocardial performance in patients after bypass surgery for coronary artery disease.

METHODS

Forty-three patients scheduled for elective or urgent coronary artery bypass grafting were prospectively recruited in two-arm 1:1 randomized parallel groups to either receive 20 mg of adenosine (in 21 patients) or saline (in 22 patients) into the aortic root during the first potassium-enriched blood cardioplegia infusion. The main outcomes of the study were ventricular myocardial performance measured with cardiac index, right ventricular stroke work index, and left ventricular stroke work index at predefined time points and time to asystole after a single bolus injection of adenosine. Conventional myocardial biomarkers were compared between the two groups at predefined time points as secondary endpoints. Electrocardiographic data and other ad hoc clinical outcomes were compared between the groups.

RESULTS

Compared with saline, adenosine reduced the time to asystole (68 (95% confidence interval (95% CI) = 37-100) versus 150 (95% CI = 100-210) seconds, p = 0.005). With myocardial performance, the results were inconclusive, since right ventricular stroke work index recovered better in the adenosine group (p = 0.008), but there were no significant overall differences in cardiac index and left ventricular stroke work index between the groups. Only the post-cardiopulmonary bypass cardiac index was better in the adenosine group (2.3 (95% CI = 2.2-2.5) versus 2.1 (95% CI = 1.9-2.2) L/min/m², p = 0.016). There were no significant differences between the groups in cardiac biomarker values.

CONCLUSIONS

A high dose adenosine bolus at the beginning of the first cardioplegia infusion resulted in significantly faster asystole in coronary artery bypass grafting patients but enhanced only partially the ventricular performance.EudraCT number: 2014-001382-26. https://www.clinicaltrialsregister.eu/ctr-search/trial/2014-001382-26/FI.

The Hypoxia-Adenosine Link during Myocardial Ischemia-Reperfusion Injury

Despite increasing availability and more successful interventional approaches to restore coronary reperfusion, myocardial ischemia-reperfusion injury is a substantial cause of morbidity and mortality worldwide. During myocardial ischemia, the myocardium becomes profoundly hypoxic, thus causing stabilization of hypoxia-inducible transcription factors (HIF). Stabilization of HIF leads to a transcriptional program that promotes adaptation to hypoxia and cellular survival. Transcriptional consequences of HIF stabilization include increases in extracellular production and signaling effects of adenosine. Extracellular adenosine functions as a signaling molecule via the activation of adenosine receptors. Several studies implicated adenosine signaling in cardioprotection, particularly through the activation of the Adora2a and Adora2b receptors. Adenosine receptor activation can lead to metabolic adaptation to enhance ischemia tolerance or dampen myocardial reperfusion injury via signaling events on immune cells. Many studies highlight that clinical strategies to target the hypoxia-adenosine link could be considered for clinical trials. This could be achieved by using pharmacologic HIF activators or by directly enhancing extracellular adenosine production or signaling as a therapy for patients with acute myocardial infarction, or undergoing cardiac surgery.