Effect of preoperative statin therapy on patients undergoing isolated and combined valvular heart surgery
Borger MA, Seeburger J, Walther T, Borger F, Rastan A, Doesnst T, Mohr R.
Annals of Thoracic Surgery 2010;89:773-80.
Reviewer: Nanhi Mitter, MD
Johns Hopkins Hospital, Baltimore, MD
Borger et al present the first single-center, retrospective study involving 10,061 patients undergoing isolated or combined valvular surgery in order to better understand the role of the administration of statins perioperatively in this patient population. Patients receiving statin therapy (group 1, n = 4,216) and patients not receiving preoperative statin therapy (group 2, n=5,538) were compared and the following outcome variables were measured: 30-day mortality, myocardial infarction (MI), low cardiac output syndrome, mortality and combination of cardiac morbidity and/or mortality (combined outcome). Although there was no significant difference between the two groups with respect to MI and 30d-mortality (7.5% vs. 6.6% for group 1 vs. group 2, respectively, p = 0.08), there was a significant difference with respect to low cardiac output syndrome (8.4% vs. 6.0% in group 1 and group 2, respectively, p<0.001) and the combined outcome (11.8% vs. 9.6% in group 1 and group 2, respectively, p<0.01). Multivariate logistic regression analysis failed to identify preoperative statin therapy as an independent predictor of a combined outcome of MI, low cardiac output syndrome, and 30-day mortality. A univariate analysis revealed the long term postoperative survival to be significantly less for patients who were on preoperative statin therapy versus those who were not (76.6% vs. 79.2% in group 1 and group 2, respectively, p<0.001). In a subgroup analysis of patients undergoing concomitant coronary artery bypass grafting (CABG) statins did not have a significant effect on perioperative mortality (p=0.2) or combined morbidity and mortality (p=0.2). It was found however, in this subgroup of patients, that patients on statin therapy did have better long term survival (p=0.003).
The role of statins perioperatively has been the topic of much debate and there is conflicting evidence in the literature as far as the significance, mechanism of action and optimal timing of therapy. Furthermore it is unclear whether or not it is statins alone that exert myocardial protective effects or if the combination of statins along with other agents such as beta blockers and aspirin (as is often seen in this patient population) results in improved outcomes. Based on their data, Borger and colleagues surmise that there is currently insufficient evidence to routinely administer statins in this patient population.
There are a few limitations to this study. Firstly, it is retrospective and single center in its design. Secondly, preoperatively the statin group had a higher EuroSCORE predicted risk of mortality due to the increased prevalence of risk factors such as advanced age, left ventricular dysfunction, peripheral vascular disease, precious cardiac surgery and neurological event. Moreover, the study did not account for type, dose and duration of statin use. Finally, the anesthetic regimen was not standardized which is now an interesting paradigm as the role of the intraoperative anesthetic regimen is being found to impact postoperative outcomes after cardiac surgery.
Regardless of the limitations, this study has important and practical implications with respect to the need and/or appropriateness of statins in patients undergoing valvular surgery. What is needed, as stated by the authors, are further randomized control trials which may be a possibility in patients undergoing valvular surgery (although not possible in patients undergoing CABG surgery as statin administration is an established norm in these patients). Given the sample size however, it would be interesting to determine what effect, if any, statin therapy has on other perioperative complications such as atrial fibrillation, and whether or not this effect is truly unique and not a result of synergistic benefit of statins with other commonly administered agents in the perioperative period (beta-blockers, aspirin, etc).
Overall, Borger et al reveal the lack of an immediate beneficial effect of statins in patients undergoing isolated or combined valvular surgery but some beneficial effect in long term survival that may be seen in patients undergoing combined valve and CABG surgery.