Myocardial Protection With Different Cardioplegia in Adult Cardiac Surgery: A Network Meta-Analysis

AIM

Cardioplegia is one of the most studied fields of myocardial protection during cardiac surgery. However, the most effective cardioplegia for protection in adult cardiac surgery remains unknown.

METHOD

PubMed and other databases were searched and a network meta-analysis with a Bayesian framework was performed. The primary outcomes were the serum concentrations of creatine kinase-myocardial band (CK-MB), cardiac troponin I, and cardiac troponin T (cTnT) at four time points. Several clinical outcomes were evaluated, including low output syndrome, myocardial infarction, and risk of early mortality. All studies that involved crystalloid cardioplegia without reference to St Thomas cardioplegia or histidine-tryptophan-ketoglutarate solution, and if the cardioplegia was used at a temperature between 4°C and 16°C were classified as cold crystalloid (cCCP) or cold blood cBCP cardioplegia. Warm blood cardioplegia (wBCP) was defined as the blood cardioplegia used at a temperature between 32°C and 37°C.

RESULTS

Forty-seven (47) studies with a total of 4,175 patients were included. Seven (7) cardioplegia solutions were used, including cold CCP or BCP, del Nido solution, histidine-tryptophan-ketoglutaratesolution, St Thomas cardioplegia, wBCP and warm terminal blood cardioplegia (wtBCP). The serum concentrations of CK-MB at 2 hours (mean difference [MD], 213.56; 95% confidence interval [CI], -25.79 to -1.59) and cTnT at 24 hours of wBCP (MD, -1.50; 95% CI, -2.69 to -0.31) were significantly lower than that of cCCP. There were no significant differences in other outcomes of these six cardioplegia solutions, when compared to cCCP.

CONCLUSIONS

The seven cardioplegia solutions analysed had similar myocardial protective effects after adult cardiac surgery, although wBCP had a lower CK-MB at 2 hours and lower cTnT at 24 hours.

Warm Blood Cardioplegia for Myocardial Protection: Concepts and Controversies

Warm blood cardioplegia has been an established cardioplegic method since the 1990s, yet it remains controversial in regard to myocardial protection. This review will describe the physiologic and technical concepts behind warm blood cardioplegia, as well as outline the current basic and clinical research that evaluates its usefulness. Controversies regarding this technique will also be reviewed. A long history of experimental data indicates that warm blood cardioplegia is safe and effective and thus suitable myocardial protection during cardiopulmonary bypass surgeries.

Cold blood cardioplegia reduces the increase in cardiac enzyme levels compared with cold crystalloid cardioplegia in patients undergoing aortic valve replacement for isolated aortic stenosis

OBJECTIVES

Cardiac arrest during cardiac surgery is most commonly induced by cold blood or cold crystalloid cardioplegia. The results from clinical studies are divergent regarding which of the 2 solutions provides better myocardial protection. This might be explained by several factors. Both heterogeneity in disease for the included patients and the fact that most studies are retrospective in design and that patients with coronary artery disease with different degrees of myocardial ischemia are included might explain these findings. To circumvent these potentially confounding factors, we included in a prospective randomized study only patients undergoing aortic valve replacement for aortic stenosis without other significant cardiac disease. Patients were randomized to antegrade cold crystalloid or cold blood cardioplegia.

METHODS

Eighty patients with aortic stenosis undergoing aortic valve replacement without significant coronary artery stenosis or other significant concomitant heart valve disease were included in the study. They were randomized to either antegrade cold blood or cold crystalloid cardioplegic solution delivered through the coronary ostia every 20 minutes throughout the period of aortic crossclamping. Maximum postoperative creatine kinase isoenzyme MB and troponin-T levels, well-established markers of myocardial damage, were compared between the 2 groups.

RESULTS

Both maximum postoperative creatine kinase isoenzyme MB and troponin-T levels were significantly higher by approximately 100% in the cohort of patients receiving crystalloid compared with blood cardioplegia. Only in the group of patients receiving cold crystalloid cardioplegia was there a positive correlation between cardiac enzyme levels and crossclamp time.

CONCLUSION

Antegrade cold blood cardioplegia provides better myocardial protection than cold crystalloid cardioplegia in patients undergoing aortic valve replacement.

Is blood superior to crystalloid cardioplegia? A meta-analysis of randomized clinical trials

BACKGROUND

Many small, randomized, controlled trials have evaluated the effectiveness of blood as compared with crystalloid cardioplegia for myocardial protection during cardiac surgery. Blood cardioplegia provides a closer approximation to normal physiology, which may translate into measurable clinical benefits. This meta-analysis describes the effectiveness of blood cardioplegia in lowering adverse postoperative outcomes.

METHODS AND RESULTS

MEDLINE, EMBASE, and the Cochrane registry of controlled trials were searched for clinical trials. The search was restricted to peer-reviewed English language publications of randomized controlled trials that primarily compared blood and crystalloid cardioplegia in adult patients. Each trial was blindly assessed and abstracted by 2 reviewers. The primary outcomes were: low output syndrome (LOS), myocardial infarction (MI), and death. Surrogate outcomes included postoperative creatinine kinase MB (CKMB) increase. Random effects summary odds ratio (OR) for binary outcomes, and weighted mean difference for continuous outcomes were calculated. A total of 34 trials were included. The majority of trials were conducted in patients undergoing elective CABG surgery (n=18). The incidence of LOS was decreased significantly with blood cardioplegia (OR, 0.54; 95% confidence interval [CI], 0.34 to 0.84; P=0.006; 879 patients, 10 trials). The incidence of MI and death were similar between treatment groups (MI: OR, 0.78; 95% CI, 0.54 to 1.13; 4316 patients, 23 trials) (death: OR, 0.80; 95% CI, 0.46 to 1.40; 4022 patients, 17 trials). CKMB release after surgery at 24 hours was reduced with blood cardioplegia (5.9 U/L; 95% CI, 1.6 to 10.2; P=0.007; 821 patients, 7 trials).

CONCLUSIONS

Blood cardioplegia provides superior myocardial protection as compared with crystalloid cardioplegia, including lower rates of LOS, and early CKMB increase, whereas the incidence of myocardial infarction and death are similar.