Background
Preoperative risk prediction in patients at elevated cardiovascular risk shows limited accuracy. Platelet to lymphocyte ratio (PLR) and neutrophil to lymphocyte ratio (NLR) indicate systemic inflammation. Both have been investigated for outcome prediction in the field of oncology and cardiovascular medicine, as well as risk prediction of adverse cardiovascular events in non-surgical patients at increased cardiovascular risk.
Methods
For this post-hoc analysis, we included all 38 coronary heart disease patients from the Leukocytes and Cardiovascular Perioperative Events cohort-1 study scheduled for elective non-cardiac surgery. We evaluated preoperative differential blood counts for association with major adverse cardiovascular and cerebrovascular events (MACCE) defined as the composite endpoint of death, myocardial ischemia, myocardial infarction, myocardial injury after non-cardiac surgery, or embolic or thrombotic stroke within 30 days after surgery. We used Youden’s index to calculate cut-off values for PLR and NLR. Additive risk-predictive values were assessed using receiver operating characteristic curve and net reclassification (NRI) improvement analyses.
Results
Patients with the composite endpoint MACCE had higher PLR and NLR (309 [206; 380] vs. 160 [132; 203], p = 0.001; 4.9 [3.5; 8.1] vs. 2.6 [2.2; 3.4]), p = 0.001). Calculated cut-offs for PLR > 204.4 and NLR > 3.1 were associated with increased risk of 30-day MACCE (OR 7, 95% CI [1.2; 44.7], p = 0.034; OR 36, 95% CI [1.8; 686.6], p = 0.001). Furthermore, NLR improved risk prediction in coronary heart disease patients undergoing non-cardiac surgery when combined with hs-cTnT or NT-proBNP (NRI total = 0.23, p = 0.008, NRI total = 0.26, p = 0.005).
Conclusions
Both PLR and NLR were associated with perioperative cardiovascular adverse events in coronary heart disease patients. NLR proved to be of additional value for preoperative risk stratification. Both PLR and NLR could be used as inexpensive and broadly available tools for perioperative risk assessment.
Trial registration
NCT02874508, August 22, 2016.
Immune cells drive atherosclerotic lesion progression and plaque destabilization. Coronary heart disease patients undergoing noncardiac surgery are at risk for perioperative major adverse cardiac and cerebrovascular events (MACCE). It is unclear whether differential leukocyte subpopulations contribute to perioperative MACCE and thereby could aid identification of patients prone to perioperative cardiovascular events. First, we performed a hypothesis-generating post hoc analysis of the LeukoCAPE-1 study (n = 38). We analyzed preoperative counts of 6 leukocyte subpopulations in coronary heart disease patients for association with MACCE (composite of cardiac death, myocardial infarction, myocardial ischemia, myocardial injury after noncardiac surgery, thromboembolic stroke) within 30 d after surgery. Regulatory T cells (Tregs) were the only leukocyte subgroup associated with MACCE. We found reduced Tregs in patients experiencing MACCE versus no-MACCE (0.02 [0.01; 0.03] vs. 0.04 [0.03; 0.05] Tregs nl −1 , P = 0.002). Using Youden index, we derived the optimal threshold value for association with MACCE to be 0.027Tregs nl −1 . Subsequently, we recruited 233 coronary heart disease patients for the prospective, observational LeukoCAPE-2 study and independently validated this Treg cutoff for prediction of MACCE within 30 d after noncardiac surgery. After multivariate logistic regression, Tregs < 0.027 cells nl −1 remained an independent predictor for MACCE (OR = 2.54 [1.22; 5.23], P = 0.012).Tregs improved risk discrimination of the revised cardiac risk index based on ΔAUC (area under the curve; ΔAUC = 0.09, P = 0.02), NRI (0.26), and IDI (0.06). Preoperative Treg levels below 0.027 cells nl −1 predicted perioperative MACCE and can be measured to increase accuracy of established preoperative cardiac risk stratification in coronary heart disease patients undergoing noncardiac surgery.
Noncardiac surgery was associated with an increase in atherogenic leukocyte subsets. In a post hoc analysis, elevated pre-OP presepsin was associated with MACCE and improved NT-proBNP-based risk assessment. After validation in an independent data set, a presepsin cutoff of 184 pg·mL might qualify to complement NT-proBNP-based risk prediction, thereby increasing the proportion of correctly identified high-risk patients.
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