18F-FDG PET/CT in left ventricular assist device infections: In-depth characterization and clinical implications.

BACKGROUND: Previous retrospective studies suggest a good diagnostic performance of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET)/computed tomography (CT) in left ventricular assist device (LVAD) infections. Our aim was to prospectively evaluate the role of PET/CT in the characterization and impact on clinical management of LVAD infections. METHODS: A total of 40 patients (aged 58 [53-62] years) with suspected LVAD infection and 5 controls (aged 69 [64-71] years) underwent 18F-FDG-PET/CT. Four LVAD components were evaluated: exit site and subcutaneous driveline (peripheral), pump pocket, and outflow graft. The location with maximal uptake was considered the presumed site of infection. Infection was confirmed by positive culture (exit site or blood) and/or surgical findings. RESULTS: Visual uptake was present in 40 patients (100%) in the infection group vs 4 (80%) control subjects. For each individual component, the presence of uptake was more frequent in the infection than in the control group. The location of maximal uptake was most frequently the pump pocket (48%) in the infection group and the peripheral components (75%) in the control group. Maximum standard uptake values (SUVmax) were higher in the infection than in the control group: SUVmax (average all components): 6.9 (5.1-8.5) vs 3.8 (3.7-4.3), p = 0.002; SUVmax (location of maximal uptake): 10.6 ± 4.0 vs 5.4 ± 1.9, p = 0.01. Pump pocket infections were more frequent in patients with bacteremia than without bacteremia (79% vs 31%, p = 0.011). Pseudomonas (32%) and methicillin-susceptible Staphylococcus aureus (29%) were the most frequent pathogens and were associated with pump pocket infections, while Staphylococcus epidermis (11%) was associated with peripheral infections. PET/CT affected the clinical management of 83% of patients with infection, resulting in surgical debridement (8%), pump exchange (13%), and upgrade in the transplant listing status (10%), leading to 8% of urgent transplants. CONCLUSIONS: 18F-FDG-PET/CT enables the diagnosis and characterization of the extent of LVAD infections, which can significantly affect the clinical management of these patients.

Successful heart transplantation in patients with total artificial heart infections.

BACKGROUND: Data are limited on clinical outcomes in patients awaiting heart transplant (HT) with total artificial heart (TAH) infections. METHODS: We retrospectively reviewed all TAH recipients at our center. TAH infection was classified as definite if a microorganism was isolated in cultures from the exit site or deep tissues around the TAH; as probable in patients without surgical or microbiologic evidence of infection but no other explanation for persistent or recurrent bloodstream infection (BSI); or possible in patients with clinical suspicion and radiographic findings suggestive of TAH infection, but without surgical intervention or microbiologic evidence. RESULTS: From 2012 to 2015, a total of 13 patients received a TAH, with a median age at implantation of 52 years (range: 28-60). TAH infection occurred in nine patients (seven definite, one probable, one possible) a median of 41 days after implant (range: 17-475). The majority of TAH infections were caused by Staphylococcus species. Seven of nine patients underwent HT (four had pre-HT mediastinal washout, and five had positive HT operative cultures). Three patients had an active BSI caused by the same pathogen causing TAH infection at the time of HT, with one developing a post-HT BSI with the same bacteria. No patient developed post-HT surgical site infection caused by the TAH infection pathogen. No deaths among HT recipients were attributed to infection. CONCLUSION: TAH infection is frequently associated with BSI and mediastinitis and Staphylococcus was the most common pathogen. A multimodal approach of appropriate pre- and post-HT antimicrobial therapy, surgical drainage, and heart transplantation with radical mediastinal debridement was successful in curing infection.

Left ventricular assist devices improve functional class without normalizing peak oxygen consumption.

Heart failure patients supported with left ventricular assist devices (LVAD) enjoy improvements in functional capacity and quality of life. We reasoned that such improvements in exercise capacity should be reflected in an objective increase in peak oxygen consumption as measured by cardiopulmonary exercise testing (CPET). We performed a retrospective review of all recipients of a HeartMate II LVAD at our center from June 2009 to June 2012 who completed CPET. Thirty-seven patients completed CPET an average of 6 months after implantation. Of these, 10 patients had CPET performed before LVAD implantation. Overall, 91.4% of patients improved by at least two New York Heart Association classes, with 34.3% improving by three classes. Postimplant VO2 max was significantly less than predicted (14.7 ± 3.1 vs. 29.8 ± 6.6 ml/kg/min, p < 0.001; percent-predicted 51% ± 12%). For 10 patients with pre- and post-implant studies, VO2 max increased significantly from 11.6 ± 5.0 to 15.4 ± 3.9 ml/kg/min (p = 0.009). VO2 max improves significantly with LVAD support but fails to normalize to predicted values, in spite of improvements in functional class. The severity of preimplantation heart failure does not associate with the degree of VO2 max improvement.

Implantable left ventricular assist devices as initial therapy for refractory postmyocardial infarction cardiogenic shock.

OBJECTIVES: Recently, the initial therapy for refractory cardiogenic shock has largely been based on use of short-term mechanical devices with later conversion to durable options. The premise is that such patients cannot tolerate cardiopulmonary bypass and the extended surgery needed for implantable left ventricular assist device (LVAD) placement. We have adopted an alternative strategy to implant long-term LVADs as the initial device therapy in such patients. METHODS: Over a 3 year period, we used implantable LVADs (Jarvik 2000, one; Ventrassist, one; Heartmate XVE, two; and Heartmate II, nine) in 13 patients (11 men and two women; mean age 54 years) with postmyocardial infarction shock without prior use of a short-term LVAD. The median time interval from myocardial infarction to LVAD implantation was 3.5 days. Eight patients were on a ventilator, two had unknown neurological status and four had suffered cardiac arrest in the preceding 24 h. Two had prior coronary artery bypass graft. Nine had received dual antiplatelet therapy postmyocardial infarction. The mean laboratory value of creatinine was 1.5 mg/dl, alanine aminotransferase 748 U/l, international normalized ratio 1.5 and lactate 3.2 mmol/l. One procedure was carried out off pump; for the others, the mean cardiopulmonary bypass time was 72 min. Right ventricular assist devices were used in two cases and were later explanted. RESULTS: One patient died of progressive multiorgan failure. All others survived to hospital discharge. There were no re-explorations for bleeding or major infectious complications; two patients had perioperative stroke. The median duration of mechanical ventilation, intensive care unit stay and hospital stay was 3, 9 and 18 days, respectively. At 1 year, of the 12 survivors, eight have since had heart transplant, one patient underwent device explant, two remained alive on support and one died 7 months post-LVAD. CONCLUSIONS: Our data challenge the notion that patients in refractory cardiogenic shock are too ill to tolerate immediate placement of implantable LVADs. Despite the surgical challenges, a one-stop implantable LVAD approach for cardiogenic shock is feasible and may offer unique advantages over the bridge-to-bridge approach because it avoids the incremental costs, hospitalization and morbidity associated with repeated interventions.