DISCUSSION

Although the number of patients undergoing TAVI is rapidly increasing, few studies have described the infection-related morbidity associated with this procedure. Infection was reported to be the most common cause of death in those who died more than 48 hours but less than 30 days after the procedure, and infection was also a major cause of hospital readmission.Reference Van Mieghem, van der Boon and Nuis ³ Our post-TAVI infection rate of 13.8% is similar to the 10%–20% found in other studies, despite varying surveillance methods.Reference van der Boon, Nuis and Benitez ^{4 ,} Reference Barbash, Finkelstein and Barsheshet ⁵ The incidence of infective endocarditis in the first year post-TAVI in our study (1.6%) was also consistent with previous reports indicating that this life-threatening complication may occur in up to 3.4% of patients.Reference Amat-Santos, Messika-Zeitoun and Eltchaninoff ^{6 ,} Reference Olsen, de backer and Thyregod ⁷

Risk factors associated with the development of infection after TAVI are poorly understood, and many may not be modifiable. We identified underlying COPD as a risk factor, and other studies have identified additional patient-related characteristics such as obesity and increased Society of Thoracic Surgeons (STS) risk score as variables associated with an increased risk of infection.Reference van der Boon, Nuis and Benitez ^{4 ,} Reference Barbash, Finkelstein and Barsheshet ⁵ In univariate analysis, surgical cannulation of the femoral artery was associated with infection, as previously reported,Reference van der Boon, Nuis and Benitez ⁴ but unlike a previous study, we did not identify an increased risk of infection with a transapical approach,Reference Biancari, Rosato and D’Errigo ⁸ perhaps because only a few patients in our study had the procedure done in this way. We found that postprocedural hemorrhage requiring transfusion modestly but significantly increased the risk of infection. Because major bleeding following TAVI has been associated with the use of large bore arterial sheath,Reference Van Mieghem, Tchetche and Chieffo ⁹ the use of smaller bore instruments with some of the newer implantable devices should be considered when feasible. As reported previously, we found stroke complicating TAVI to be a strong predictor of infection.Reference van der Boon, Nuis and Benitez ⁴ The mechanism for this association may be multifactorial, including an increased risk of aspiration or use of urinary catheters. Evaluation of embolic protection devices to reduce the risk of embolic stroke following TAVI is warranted, and their use may also reduce the risk of infection.Reference Egron, Kütting, Marzelle, Becquemin, Schmitz-Rode and Steinseifer ¹⁰ Optimizing and reducing the use of urinary catheters may contribute to lowering the risk of postprocedural urinary tract infections.

The strengths of this study include the cohort study design and the use of standardized infection criteria. However, the study describes the experience of only a single academic center, with a relatively small number of infections. In our retrospective chart review, infections may have been missed or misdiagnosed. A few patients did not have a full year of follow-up for endocarditis post procedure. The results describe associations between certain variables and infection but do not necessarily imply a causal relationship. Although an effort was made to account for confounders in the analysis of variables associated with infection, we may not have accounted for all confounders.

In summary, infection is an important complication in patients undergoing TAVI, associated with increased morbidity and mortality. Our results contribute to a better understanding of the incidence and risks of infection in these patients. Modifications to the procedure or technique may reduce the risk of TAVI-related infection and other complications.