A multicentre Spanish study for multivariate prediction of perioperative in-hospital cerebrovascular accident after coronary bypass surgery: the PACK2 score

Abstract

Objectives: To develop a multivariate predictive risk score of perioperative in-hospital stroke after coronary artery bypass grafting (CABG) surgery.

Method: A total of 26 347 patients were enrolled from 21 Spanish hospital databases. Logistic regression analysis was used to predict the risk of perioperative stroke (ictus or transient ischaemic attack). The predictive scale was developed from a training set of data and validated by an independent test set, both selected randomly. The assessment of the accuracy of prediction was related to the area under the ROC curve. The variables considered were: preoperative (age, gender, diabetes mellitus, arterial hypertension, previous stroke, cardiac failure and/or left ventricular ejection fraction<40%, non-elective priority of surgery, extracardiac arteriopathy, chronic kidney failure and/or creatininemia≥2 mg/dl and atrial fibrillation) and intraoperative (on/off-pump).

Results: Global perioperative stroke incidence was 1.38%. Non-elective priority of surgery (priority; OR=2.32), vascular disease (arteriopathy; OR=1.37), cardiac failure (cardiac; OR=3.64) and chronic kidney failure (kidney; OR=6.78) were found to be independent risk factors for perioperative stroke in uni- and multivariate models in the training set of data; P<0.0001; AUC=0.77, 95% CI 0.73-0.82. The PACK2 stroke CABG score was established with 1 point for each item, except for chronic kidney failure with 2 points (range 0-5 points); AUC=0.76, 95% CI 0.72-0.80. In patients with PACK2 score≥2 points, off-pump reduced perioperative stoke incidence by 2.3% when compared with on-pump CABG.

Conclusions: PACK2 risk scale shows good predictive accuracy in the data analysed and could be useful in clinical practice for decision making and patient selection.

Keywords: Coronary; Off-pump; Stroke.

Figure 1:

Distribution of percentage of perioperative stroke according to range of PACK₂ score punctuations. The black fine line represents exponential tendency of increasing incidence of the perioperative stroke (y = 0.266 e^0.78; R² = 0.978).

Figure 2:

Decision tree to stratify perioperative stroke risk in the overall CABG series (n = 26 347), attending PACK₂ score and off-pump technique. OPCAB: off-pump coronary bypass surgery, CPBCAB: coronary bypass surgery in cardiopulmonary bypass, df = degree of freedom.