Noncardiac Surgery: Some Care During Mechanical Circulatory Support Should Not Be Shared

Within the past 5 years, the number of durable mechanical circulatory support (MCS) implants for management of end-stage systolic heart failure within the United States has over doubled—from 1,000 devices per year in 2009 to over 2,500 implants in 2014.1 With a median survival of 4 years after MCS implant, the overall prevalence of patients living on MCS within the community is steadily increasing.1 Freedom from first readmission is only 30% at 1 year after device implant,1 and more and more hospitals and emergency rooms are encountering (often unexpectedly) patients on MCS with device related and device unrelated medical and surgical maladies. Yet, the numbers of medical professionals within the general medical community with training in MCS are few. Thus, one can extrapolate that some hospitalized MCS patients are being cared for by practitioners with little understanding about critical MCS management issues and some MCS patients may even be admitted to hospitals without the obligatory ventricular assist device (VAD) peripherals (e.g., batteries, monitors) necessary for patient monitoring and safe device function. In this issue of ASAIO J, Taghavi et al.2 use the National Inpatient Sample database to better characterize the frequency and types of noncardiac surgeries endured by left ventricular assist device (LVAD) patients during the patient’s index MCS admission, as well as the morbidity and mortality associated with the need for noncardiac surgery (NCS). Of 1,397 patients, 21% required NCS during the index MCS stay, most of which were general surgery or vascular procedures.2 Frequencies of wound infections and bleeding complications were almost double in patients requiring NCS compared with controls.2 While inpatient mortality was not statistically different between NCS (23%) patients and controls (18%, p = 0.10), the mortality trends in MCS patients requiring NCS cannot be ignored (odds ratio [95% confidence interval] = 1.45 [0.95–2.2]) and statistical significance was likely power related.2 All of the patients in the Taghavi et al.2 analysis were being cared for at an MCS implant center, presumably with MCS medical, surgical, and anesthesia specialists on site for consultation regarding device and patient management. Despite this “ideal” specialized care setting, MCS patients still had a high burden of adverse outcomes after NCS. However, there are limitations to extrapolating NCS hazards during the index VAD implant to that of NCS in patients on longer term (e.g., >90 days postop) MCS support. Complications following MCS implant often have fluctuating hazards (Figure 1), with event hazards being highest in the early postoperative period followed by a decline in hazard around postoperative month 3.1 For some adverse events, such as infection, the mortality hazard begins to rise again as support duration increases. For other events, such as stroke, the postoperative hazard holds relatively constant after month 3.1 To date, no study has published hazard trends on the requirement for NCS during long-term MCS support and/or the hazard for mortality following NCS during chronic MCS support.Figure 1.: Hazard function curves for instantaneous risk of death from major adverse events in INTERMACS patients. INTERMACS, interagency registry for mechanically assisted circulatory support; MSOF, multisystem organ failure; RHC, right heart failure. Adapted with permission from Kirklin et al.1 (Figure 10, p. 1499). We can glean some information on overall NCS burden and morbidity during long-term MCS support from published small cohort studies (Table 1).3–9 The requirement for NCS ranges from 23% to 41%, with large variation in cumulative incidence due to study differences in patient follow-up duration and inclusion or exclusion of minor surgical procedures in the numerator. Overall, abdominal and vascular NCS procedures are predominant. Aside from two studies with no deaths, operative mortality ranges 6.4–17% at a mean 38–317 days of patient support time and bleeding and infectious complications are common.2–8 If one follows the ACC/AHA guidelines on cardiac surgical risk, this would classify the average MCS-NCS operation as high risk (>5% risk of death or infarction).10 Importantly, all published studies in Table 1 examined events occurring at MCS implanting centers and there is no data on outcomes when surgery is performed at non-MCS specialty hospitals.2–8 In addition to the high morbidity and mortality discussed herein, MCS specific factors such as vitals (blood pressure, oxygenation) monitoring during nonpulsatile support, driveline avoidance on abdominal cavity entrance and postop driveline care, anticoagulation management, and laboratory and MCS device parameter monitoring complicate the NCS procedure and postoperative management of even lower risk interventions. Thus, it is critical for patients, local emergency rooms, and local hospitals without MCS specialists to understand that unless a patient is too unstable for transfer, MCS patients requiring NCS should be cared for at an MCS specialty hospital.Table 1.: Summary of Cohort Studies Examining Noncardiac Surgery Outcomes After Mechanical Circulatory Support