β-Blockers and Volatile Anesthetics May Attenuate Cardioprotection by Remote Preconditioning in Adult Cardiac Surgery: A Meta-analysis of 15 Randomized Trials

OBJECTIVE:

Clinical trials on cardioprotection by remote
ischemic preconditioning (RIPC) for adult patients undergoing cardiac
surgery revealed mixed results. Previous meta-analyses have been
conducted and found marked heterogeneity among studies. The aim of this
meta-analysis was to evaluate the factors affecting cardioprotection by
remote preconditioning in adult cardiac surgery.

DESIGN:

A meta-analysis of randomized controlled trials.

SETTING:

University hospitals.

PARTICIPANTS:

Adult subjects undergoing cardiac surgery.

INTERVENTIONS:

RIPC.

MEASUREMENTS AND MAIN RESULTS:

Fifteen
trials with a total of 1,155 study patients reporting postoperative
myocardial biomarker (CK-MB or troponin) levels were identified from
PubMed, Embase, and the Cochrane Library (up to July 2012). Compared
with controls, RIPC significantly reduced postoperative biomarkers of
myocardial injury (standardized mean difference = -0.31, p = 0.041;
heterogeneity test: I(2) = 83.5%). This effect seemed more significant
in valve surgery (standardized mean difference = -0.74, p = 0.002) than
in coronary artery surgery (standardized mean difference = -0.23; p =
0.17). Univariate meta-regression analyses suggested that the major
sources of significant heterogeneity were β-blockers (%) (coefficient =
0.0161, p = 0.022, adjusted R(2) = 0.37) and volatile anesthetics
(coefficient = 0.6617, p = 0.065, adjusted R(2) = 0.22). These results
were further confirmed in multivariate regression and subgroup analyses.

CONCLUSIONS:

Available
data from this meta-analysis further confirmed the cardioprotection
conferred by RIPC in adult cardiac surgery. Moreover, the
cardioprotective effect may be attenuated when combined with β-blockers
or volatile anesthetics.