Increased levels of NT-proBNP and troponin T 2 years after coronary artery bypass grafting complicated by mediastinitis

Clinical profile, microbiology and outcomes in infective endocarditis treated with aortic valve replacement: a multicenter case-control study

BACKGROUND

Aortic valve infective endocarditis (IE) is associated with significant morbidity and mortality. We aimed to describe the clinical profile, risk factors and predictors of short- and long-term mortality in patients with aortic valve IE treated with aortic valve replacement (AVR) compared with a control group undergoing AVR for non-infectious valvular heart disease.

METHODS

Between January 2008 and December 2013, a total of 170 cases with IE treated with AVR (exposed cohort) and 677 randomly selected non-infectious AVR-treated patients with degenerative aortic valve disease (controls) were recruited from three tertiary hospitals with cardiothoracic facilities across Scandinavia. Crude and adjusted hazard ratios (HR) were estimated using Cox regression models.

RESULTS

The mean age of the IE cohort was 58.5 ± 15.1 years (80.0% men). During a mean follow-up of 7.8 years (IQR 5.1-10.8 years), 373 (44.0%) deaths occurred: 81 (47.6%) in the IE group and 292 (43.1%) among controls. Independent risk factors associated with IE were male gender, previous heart surgery, underweight, positive hepatitis C serology, renal failure, previous wound infection and dental treatment (all p < 0.05). IE was associated with an increased risk of both short-term (≤ 30 days) (HR 2.86, [1.36-5.98], p = 0.005) and long-term mortality (HR 2.03, [1.43-2.88], p < 0.001). In patients with IE, chronic obstructive pulmonary disease (HR 2.13), underweight (HR 4.47), renal failure (HR 2.05), concomitant mitral valve involvement (HR 2.37) and mediastinitis (HR 3.98) were independent predictors of long-term mortality. Staphylococcus aureus was the most prevalent microbe (21.8%) and associated with a 5.2-fold increased risk of early mortality, while enterococci were associated with the risk of long-term mortality (HR 1.78).

CONCLUSIONS

In this multicenter case-control study, IE was associated with an increased risk of both short- and long-term mortality compared to controls. Efforts should be made to identify, and timely treat modifiable risk factors associated with contracting IE, and mitigate the predictors of poor survival in IE.

Troponin T and N-Terminal Pro-Brain Natriuretic Peptide Are Associated with Long-Term All-Cause Mortality in Patients with Post-Sternotomy Mediastinitis following Coronary Artery Bypass Grafting: A 15-Year Follow-Up Study

BACKGROUND

Deep sternal wound/mediastinitis is a rare but feared complication in coronary artery bypass grafting (CABG) patients and seems to increase the risk of cardiac death, and is also associated with the risk of early internal mammary artery (IMA) graft obstruction. The pathological mechanism explaining the link between mediastinitis and IMA graft obstruction and the impact on mortality is complex, multifactorial, and not fully investigated.

OBJECTIVES

Mediastinitis has been associated with increased concentrations of N-terminal pro-brain natriuretic peptide (NT-proBNP) and troponin T (TnT) at mid-term follow-up, representing persistent low-grade myocardial injury and impaired cardiac function. However, whether mediastinitis is associated with all-cause mortality, or whether the association is driven by these cardiac-specific biomarkers (NT-proBNP and TnT), is not investigated.

METHODS

The present study provides the longest and most complete follow-up data in 82 patients undergoing CABG, including 41 with post-sternotomy mediastinitis.

RESULTS

The annualized incidence rate of mediastinitis was 0.14%/year and remained stable at 0.14% throughout the study period. During a mean follow-up of 12.7 ± 3.5 years, a total of 42 deaths occurred (27 [65.9%] in mediastinitis and 15 [36.6%] in non-mediastinitis group, p = 0.008). No association was found between IMA or saphenous vein graft obstruction with all-cause mortality. Mediastinitis was associated with a 1.9-fold increased risk of all-cause mortality. However, in the multivariable-adjusted models, age and higher TnT and NT-proBNP levels, but not mediastinitis per se were associated with all-cause mortality.

CONCLUSIONS

Mediastinitis after CABG surgery was associated with a poor prognosis during a 15-year follow-up, showing a nearly two-fold higher frequency of all-cause mortality compared with non-mediastinitis group, with the differences in mortality rate occurring primarily after 10 years. The association between mediastinitis and all-cause mortality was modulated by subclinical myocardial damage and stretch, reflected by elevated TnT and NT-proBNP, measured at 2.7-year follow-up, underscoring that these could represent prognostic markers in CABG patients.