Blood Stream Infection in Patients with Permanent Mechanical Circulatory Support: Risk Factors for On-Pump Mortality

Purpose Despite our improving knowledge, with the expanding use of mechanical circulatory support for end stage heart failure device related infection is increasingly prevalent. This study aims to better characterize the impact of multiple infections over a 22 year period. Methods This is a single center retrospective study of patients with mechanical circulatory support implanted from June 1994 to December 2016. Patients were studied for the incidence of blood stream infection (BSI), and ratio BSI:number of support days. The relationship between drive line infection/colonisation and BSI was reviewed. LVAD infection and its relationship to on pump mortality, and the relationship between multiple infections and mortality was analysed. Results A total of 191 patients (males=154, females n= 37), with an average age at implant of 51.4 years (±13.8) were studied. Patients had an average INTERMACS score of 1.83 (±0.61) and the main indication was bridge to transplant. Implanted devices included 166 LVADs, 14 biventricular assist device BiVADs, 7 total artificial hearts (TAH) and, 2 C-Pulse cuff devices. Average pump implant duration was 391 days (±338), median 312 days. There were 86/191 (45%) patients with one or more BSIs. The major responsible organisms for initial BSI were staphylococcus (64%), streptococcus (9.3%), enterococcus (7%), pseudomonas (4.7%), candida (4.2%) and E coli (3.5%). There were 0.53 events per patient year (EPPY). Of these, 66 (35% of total patients, 78% of BSI episodes) were a single episode, while 17 had multiple episodes (occurring at least 7 days after index infection) and 20 were polymicrobial, (2 organisms during time on pump). Candidaemia resulted in the highest relative mortality, with 63% infected dying on pump. 61/191 (32%) had driveline infection/colonisation. There was no difference in on-pump mortality for those with a single infection compared to those without, however there was a significant difference for those with multiple infection episodes (p Conclusion The study period for this research was the entire MCS program at our centre. This has allowed for a deeper understanding into the poor prognosis of patients with greater than one BSI during their time on pump.