Statins Improve Outcome in Isolated Heart Valve Operations: A Propensity Score Analysis of 3,217 Patients

Statin treatment after surgical aortic valve replacement for aortic stenosis is associated with better long-term outcome

OBJECTIVES

The aim of this study was to evaluate the association between statin use after surgical aortic valve replacement for aortic stenosis and long-term risk for major adverse cardiovascular events (MACEs) in a large population-based, nationwide cohort.

METHODS

All patients who underwent isolated surgical aortic valve replacement due to aortic stenosis in Sweden 2006-2020 and survived 6 months after discharge were included. Individual patient data from 5 nationwide registries were merged. Primary outcome is MACE (defined as all-cause mortality, myocardial infarction or stroke). Multivariable Cox regression model adjusted for age, sex, comorbidities, valve type, operation year and secondary prevention medications is used to evaluate the association between time-updated dispense of statins and long-term outcome in the entire study population and in subgroups based on age, sex and comorbidities.

RESULTS

A total of 11 894 patients were included. Statins were dispensed to 49.8% (5918/11894) of patients at baseline, and 51.0% (874/1713) after 10 years. At baseline, 3.6% of patients were dispensed low dose, 69.4% medium dose and 27.0% high-dose statins. After adjustments, ongoing statin treatment was associated with a reduced risk for MACE [adjusted hazard ratio 0.77 (95% confidence interval 0.71-0.83). P < 0.001], mainly driven by a reduction in all-cause mortality [adjusted hazard ratio, 0.70 (0.64-0.76)], P < 0.001. The results were consistent in all subgroups.

CONCLUSIONS

The results suggest that statin therapy might be beneficial for patients undergoing surgical aortic valve replacement for aortic stenosis. Randomized controlled trials are warranted to establish causality between statin treatment and improved outcome.

Effect of statin on perioperative myocardial injury in isolated valve surgery

BACKGROUND

Statins have known pleiotropic effects that confer protection from ischemia-reperfusion injury. Because cardiopulmonary bypass is a potentially reversible ischemia-reperfusion sequence, we aimed to assess whether statin loading could help to limit myocardial injury in patients undergoing isolated heart valve replacement under cardiopulmonary bypass.

METHODS

One hundred patients with rheumatic valvular heart disease undergoing valve replacement received either a loading dose of rosuvastatin (40 mg initiated 7 days before surgery; loaded group) or no statins (non-loaded group). Cardiac troponin I, creatine kinase MB, and brain natriuretic peptide were measured at 8, 24, and 48 hours postoperatively. The primary endpoint was the extent of perioperative myocardial injury measured by the area under the curve for each biomarker.

RESULTS

Despite similar baseline levels, all biomarkers at 8, 24, and 48 h were significantly lower in the loaded group. The area under the curve of each biomarker was significantly lower in the loaded group than in the non-loaded group (troponin I: 31.43 vs. 77.21 ng·h·mL^-1, creatine kinase MB 309.31 vs. 429.12 ng·h·mL^-1, brain natriuretic peptide 5176.11 vs. 16119.31 pg·h·mL^-1, all p < 0.001). The mean changes from baseline to peak levels were also significantly lower in the loaded group. The loaded group had a shorter hospital stay but no significant difference was seen in ventilator time, inotrope time, aortic crossclamp time, cardiopulmonary bypass time, or intensive care unit stay.

CONCLUSION

In patients undergoing valve replacement, high-dose statin loading before surgery had a favorable impact on the release kinetics of various cardiac biomarkers.

Long-term survival of non-smokers undergoing coronary artery bypass surgery

OBJECTIVES

We sought to investigate long-term survival of non-smokers undergoing coronary artery bypass surgery (CABG).

METHODS

A prospective database of consecutive patients was retrospectively analysed and cross correlated with the UK strategic tracking service to evaluate survival after primary CABG. Univariate, multivariate and a propensity analyses were performed.

RESULTS

We analysed 13 337 primary CABG procedures. Median follow-up was 7 years. Kaplan-Meier survival curves demonstrate that non-smokers have a significantly improved long-term survival compared with ex- and current smokers, P < 0.0001. Cox regression analysis identified smoking status, age, diabetes, ejection fraction (EF), body mass index, cerebrovascular disease, dialysis, left internal mammary artery (LIMA) non-usage, postoperative creatinine kinase muscle-brain isoenzyme (CKMB), radial artery usage, preoperative rhythm, forced vital capacity (FVC) and logistic EuroSCORE as significant risk factors determining long-term survival. Propensity matching resulted in 3575 non-smokers being matched 1:1, with ex-smokers. After matching, univariate analysis demonstrated the significantly worse long-term survival of ex-smokers compared with non-smokers, P < 0.0001. Cox regression analysis identified smoking status, age, postoperative CKMB, cerebrovascular disease, dialysis, diabetes, EF, FVC, LIMA non-usage, radial artery used, sinus rhythm and logistic EuroSCORE as significant risk factors determining long-term survival. Survival by smoking status plotted at the mean of the covariates, prepropensity matching, demonstrated that non-smokers had a significantly better long-term survival than ex-smokers, P < 0.0001; however, after propensity matching, non-smokers under 65 years of age had a significantly worse long-term survival compared with ex-smokers, P < 0.0001.

CONCLUSIONS

Non-smokers under the age of 65 years of age have significantly worse long-term survival compared with ex-smokers after risk factor adjustment. We speculate that this is because ex-smokers have had the causative factor, smoking, removed, but non-smokers have not.

Statins and long-term survival after isolated valve surgery: the importance of valve type, position and procedure

OBJECTIVES

To investigate whether valve position, type and procedure are important factors in determining the beneficial effects of statin therapy with regard to long-term survival in patients undergoing isolated single valve surgery.

METHODS

A prospective single-institution cardiac surgery database was analysed. Univariate, multivariate stepwise linear, logistic and Cox regression analysis and propensity matching were performed to identify if statins were associated with increased survival post-valve surgery.

RESULTS

Overall mortality was 3.4% (n = 172) for all cases, n = 5013. The median follow-up was 5.8 years. Kaplan-Meier survival analysis indicated that statin therapy was beneficial for all patients undergoing isolated valve surgery, n = 5013, P = 0.03 and isolated aortic valve surgery, n = 3220, P = 0.03, but not isolated mitral valve surgery n = 1793, P = 0.4. Cox regression analysis of the study cohort revealed that statin therapy was a significant factors determining long-term survival in the study cohort, postisolated aortic valve replacement and postisolated biological aortic valve replacement. Statins therapy was not associated with an increased long-term survival post-mitral valve replacement or repair. Propensity matching resulted in 1555 patients receiving statins being matched 1:1 with those not receiving statins. The results after propensity matching concurred with that of the Cox regression analyses, demonstrating that statin therapy was significantly associated with reduced in-hospital mortality, hospital length of stay and postoperative creatinine kinase, muscle-brain isoenzyme release.

CONCLUSIONS

Previous publications have not distinguished valve type, position and repair as possible factors influencing statin-therapy outcomes. Statin therapy is associated with increased long-term survival postaortic valve replacement with a biological valve only. Statin therapy had no survival benefit in patients undergoing mitral valve repair or a mechanical valve replacement. A randomized trial is necessary to confirm or refute our findings.

Can statins improve outcomes after isolated cardiac valve surgery? A systematic literature review

BACKGROUND

HMG CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors, or statins, have been associated with an improvement in outcomes after coronary artery surgery for some time; however, their role in isolated valve surgery (IVS) remains undetermined.

HYPOTHESIS

The pleiotropic effects of statins may produce similar beneficial effects on outcomes after IVS.

METHODS

A systematic review of the literature was performed investigating the role of statins in bioprosthetic valve replacement.

RESULTS

Nine observational studies (7 retrospective, 2 prospective) incorporating a total of 18 154 patients were found investigating the role of statin therapy in bioprosthetic valve replacement.

CONCLUSIONS

There is presently insufficient evidence to recommend routine statin therapy in IVS, unless concomitant hypercholesterolemia or coronary artery disease is present. A prospective study clearly defining the dose, type, and duration of therapy is now required to finally clarify whether statins alone confer a postoperative benefit in these patients.

Opportunities for minimization of confounding in observational research

Observational epidemiological studies are increasingly used in pharmaceutical research to evaluate the safety and effectiveness of medicines. Such studies can complement findings from randomized clinical trials by involving larger and more generalizable patient populations by accruing greater durations of follow-up and by representing what happens more typically in the clinical setting. However, the interpretation of exposure effects in observational studies is almost always complicated by non-random exposure allocation, which can result in confounding and potentially lead to misleading conclusions. Confounding occurs when an extraneous factor, related to both the exposure and the outcome of interest, partly or entirely explains the relationship observed between the study exposure and the outcome. Although randomization can eliminate confounding by distributing all such extraneous factors equally across the levels of a given exposure, methods for dealing with confounding in observational studies include a careful choice of study design and the possible use of advanced analytical methods. The aim of this paper is to introduce some of the approaches that can be used to help minimize the impact of confounding in observational research to the reader working in the pharmaceutical industry.