Abstract
BACKGROUND:
This study evaluates the impact of the 2018 allocation policy change on outcomes of orthotopic heart transplantation (OHT) in patients bridged with intra-aortic balloon pumps (IABPs).
METHODS:
Adult (≥18 years) patients undergoing OHT between 2013 and 2019 who were bridged with an IABP were stratified based on temporal relation to the policy change. Univariate analysis was used to compare baseline characteristics and postoperative outcomes. Multivariate Cox regression analysis was used to estimate risk-adjusted predictors of post-transplant mortality.
RESULTS:
A total of 1342 (8.6%) OHT patients were bridged with an IABP during the study period. Rates of bridging with IABP to OHT increased significantly after the policy change (7.0% versus 24.9%, P<0.001). The mean recipient age was 54.1±12.1 years with 981 (73.1%) patients being male. Baseline characteristics were similar between the 2 groups whereas post–policy change patients spent fewer days on the waitlist (15 versus 35 days, P<0.001), had longer ischemic times (3.5 versus 3.0 hours, P<0.001), and received organs from a greater distance (301 versus 105 miles, P<0.001). By multivariable analysis, days on the waitlist (for every 30 days; odds ratio, 1.01 [95% CI, 1.00–1.02], P=0.031) and diabetes mellitus (odds ratio, 1.87 [95% CI, 1.16–3.02], P=0.011) emerged as significant predictors of post-transplant mortality. After the policy change, waitlisted patients requiring IABP support were more likely to survive to transplant (76.4 versus 89.8%, P<0.001).
CONCLUSIONS:
IABP utilization has increased over 3-fold since the 2018 policy change with improved waitlist outcomes and comparable post-OHT survival. Thus, bridging patients to OHT with IABPs appears to be an effective strategy in the current era.
Keywords: heart failure, heart transplantation, retrospective studies
In October 2018, the United Network for Organ Sharing (UNOS) issued a policy change impacting allocation for adults waitlisted for orthotopic heart transplantation (OHT).1 With this update, patients bridged with intra-aortic balloon counterpulsation (IABP) were designated as status 2, thereby prioritizing these recipients and expanding the geographic distribution of the potential donor pool.1 Prior studies on IABP use preceding OHT are scarce but have demonstrated safety, improvement in hemodynamics, and comparable post-OHT mortality.2–4 One study of UNOS recipients, however, found worse survival among those bridged with an IABP and suggested the use of durable left ventricular assist devices (LVADs) to improve outcomes.5 Under the new allocation policy, patients supported with durable LVADs have reduced priority to status 4, which is a relatively lower prioritization when compared with the prior allocation policy. In light of these new allocation priorities, provider bias may theoretically influence decision for IABP use, and therefore listing as status 2, even though strict hemodynamic criteria for qualification for IABP support exist. Thus, the baseline characteristics of these patients, and by extension their outcomes, may reflect this paradigm shift.6 We aimed to explore outcomes among patients bridged with IABP who underwent OHT either before or after the policy change to improve understanding of the impact of this policy change on recipient selection for IABP and resulting OHT outcomes.
METHODS
Data Source
Because of the sensitive nature of the data collected for this study, requests to access the data set from qualified researchers trained in human subject confidentiality protocols may be sent to UNOS. Data were obtained from the UNOS registry which provides information on all solid organ transplants in the United States. This study was approved by the Institutional Review Board at the University of Pittsburgh.
Study Population
All adult patients (≥18 years) who underwent OHT between January 1, 2013, and July 1, 2019, and required IABP support at the time of OHT (UNOS database variable iabp_trr) were included. Patients undergoing multiorgan transplant and those requiring other mechanical circulatory support (MCS, eg, extracorporeal membrane oxygenation, LVAD, etc) were excluded. Patients were stratified based on their date of OHT as occurring either before the policy change or after. Our main analysis was stratified based on the date of transplant, thus patients listed before October 18, 2018, but who underwent OHT on or after that date are listed in the post–policy change group. A sub-analysis was conducted excluding the patients who were listed before the policy change and underwent OHT after the policy change (Tables I through IV in the Data Supplement). Baseline characteristics, donor characteristics, and post-transplant adverse events were compared.
To analyze IABP outcomes among all patients waitlisted for OHT between 2013 and 2019, we stratified patients by their waitlist end date (eg, death, transplant, still waitlisted, etc) in relation to the policy change date. Univariate analyses were conducted to compare reasons for removal, causes of death, and length of time on the waitlist.
Statistical Analysis
Baseline characteristics are presented as frequency (percentage) for categorical variables and mean (standard deviation) or median (interquartile range) for continuous variables based on normality. For categorical variables, the Pearson χ2 test was used for categorical comparisons whereas for continuous variables the Student t test and Mann-Whitney U-test were employed. Cox regression analysis was used to estimate adjusted hazard ratios for post-OHT mortality. Kaplan-Meier analysis was conducted to model post-OHT survival.
RESULTS
A total of 1342 patients underwent OHT after bridging with IABP (Table 1). The proportion of patients bridged with an IABP increased significantly following the policy change from 7.0% to 24.9% (P<0.001; Figure 1). There were no significant differences in age (54.3 versus 53.7 years, P=0.404), sex (72.5% versus 74.4% male, P=0.45), or body mass index (26.7 versus 26.4, P=0.60). OHT patients after the policy change spent fewer days on the waitlist (15 versus 35 days, P<0.001) and had longer ischemic times (3.5 versus 3.0 hours, P<0.001) with donor organs originating from a greater distance (301 versus 105 miles, P<0.001).
Table 1.
Baseline Recipient Characteristics of Patients Bridged With an Intra-Aortic Balloon Pump Who Underwent Orthotopic Heart Transplantation
| Overall (N=1342) | Pre-policy Change (N=908) | Post-policy Change (N=434) | P Value | |
|---|---|---|---|---|
| Age, y, mean±SD | 54.1±12.1 | 54.3±11.9 | 53.7±12.5 | 0.40 |
| Sex | 0.45 | |||
| Male | 981 (73.1) | 658 (72.5) | 323 (74.4) | |
| Female | 361 (26.9) | 250 (27.5) | 111 (25.5) | |
| Race, n (%) | 0.60 | |||
| White | 860 (64.4) | 575 (63.6) | 285 (66.0) | |
| Black | 307 (23.0) | 215 (23.8) | 92 (21.3) | |
| Hispanic | 115 (8.6) | 75 (8.3) | 40 (9.3) | |
| Other | 54 (4.0) | 39 (4.3) | 15 (3.5) | |
| Body mass index, kg/m2, mean±SD | 26.6±4.9 | 26.7±4.8 | 26.4±5.0 | 0.40 |
| Smoking history, n (%) | 591 (44.1) | 394 (43.4) | 197 (45.5) | 0.47 |
| Cause of heart failure, n (%) | 0.011 | |||
| Nonischemic dilated cardiomyopathy | 727 (54.2) | 464 (51.1) | 263 (60.6) | |
| Ischemic cardiomyopathy | 400 (29.8) | 299 (32.9) | 101 (23.3) | |
| Congenital | 26 (1.9) | 17 (1.9) | 9 (2.1) | |
| Valvular | 21 (1.6) | 16 (1.8) | 5 (1.2) | |
| Hypertrophic cardiomyopathy | 41 (3.1) | 27 (3.0) | 14 (3.2) | |
| Restrictive cardiomyopathy | 58 (4.3) | 38 (4.2) | 20 (4.6) | |
| Failed primary heart transplant | 42 (3.1) | 32 (3.5) | 10 (2.3) | |
| Other/unknown | 27 (2.0) | 15 (1.7) | 12 (2.8) | |
| Inotropes, n (%) | 649 (48.4) | 444 (48.9) | 205 (47.2) | 0.57 |
| Dialysis, n (%) | 6 (0.5) | 3 (0.3) | 3 (0.7) | 0.40 |
| Mechanical ventilation, n (%) | 22 (1.6) | 13 (1.4) | 9 (2.1) | 0.37 |
| Chronic steroid exposure, n (%) | 87 (6.5) | 63 (6.9) | 24 (5.5) | 0.62 |
| Diabetes mellitus, n (%) | 370 (27.6) | 258 (28.4) | 112 (25.8) | 0.32 |
| Serum creatinine, mg/dL | 1.2±0.7 | 1.3±0.8 | 1.2±0.4 | 0.006 |
| Total bilirubin, mg/dL | 0.8 [0.5–1.2] | 0.8 [0.5–1.2] | 0.8 [0.5–1.2] | 0.104 |
| Mean pulmonary artery pressure, mm Hg | 30.8±9.8 | 30.7±10.0 | 31.1±9.5 | 0.48 |
| Pulmonary capillary wedge pressure, mm Hg | 21.7±8.4 | 21.7±8.7 | 21.6±7.6 | 0.79 |
| Calculated panel reactive antibodies | 0 [0–3] | 0 [0–0] | 0 [0–5] | 0.039 |
| Blood type | 0.16 | |||
| A | 508 (37.9) | 346 (38.1) | 162 (37.3) | |
| AB | 87 (6.5) | 68 (7.5) | 19 (4.4) | |
| B | 209 (15.6) | 139 (15.3) | 70 (16.1) | |
| O | 538 (40.1) | 355 (39.1) | 183 (42.2) | |
| Functional status | 0.033 | |||
| Moribund | 1012 (75.4) | 663 (73.0) | 349 (80.4) | |
| Moderate assistance | 203 (15.1) | 152 (16.7) | 51 (11.8) | |
| No assistance | 60 (4.5) | 44 (4.9) | 16 (3.7) | |
| Unknown | 67 (5.0) | 49 (5.4) | 18 (4.2) | |
| Same sex donor/recipient | 1007 (75.0) | 660 (72.7) | 347 (80.0) | 0.004 |
| CMV matched | 744 (55.7) | 496 (54.9) | 248 (57.4) | 0.38 |
| HLA | 1107 | 761 | 346 | 0.66 |
| Mismatched | (86.9) | (87.2) | (86.3) | |
| ABO match | 1120 (83.5) | 760 (83.7) | 360 (83.0) | 0.73 |
| Days on waitlist | 29 [10–85] | 35 [13–97.5] | 15 [6–58] | <0.001 |
| Ischemic time, h | 3.2±0.9 | 3.0±0.9 | 3.5±0.8 | <0.001 |
| Distance from donor hospital, nautical miles, median (IQR) | 158 [28–350] | 105 [16–277] | 301 [131–447] | <0.001 |
CMV indicates cytomegalovirus; HLA, human leukocyte antigen; IQR, interquartile range; and SD, standard deviation.
Figure 1.
Heart transplantations in the United States each year since 2013, stratified by the use of an intra-aortic balloon pump (IABP; shown in red).
Donor age (32.2 versus 31.6 years, P=0.35), body mass index (27.3 versus 27.6 kg/m2, P=0.38), and left ventricular ejection fraction (60.9 versus 61.6%, P=0.05) were similar for pre- and post–policy change recipients (Table 2). Donors of OHT recipients after the policy change were more likely to display antigen (4.8 versus 2.2%, P=0.030) or antibody (9.0 versus 3.4%, P<0.001) positivity for hepatitis C virus.
Table 2.
Baseline Donor Characteristics Among Patients Who Were Bridged With an Intra-Aortic Balloon Pump Before Orthotopic Heart Transplantation
| Overall (N=1342) | Pre-policy Change (N=908) | Post-policy Change (N=434) | P Value | |
|---|---|---|---|---|
| Age, y, mean (standard deviation) | 32.0±10.8 | 32.2±11.1 | 31.6±10.3 | 0.35 |
| Sex | <0.001 | |||
| Male | 922 (68.7) | 588 (64.8) | 334 (77.0) | |
| Female | 420 (31.3) | 320 (35.2) | 100 (23.0) | |
| Race, n (%) | 0.79 | |||
| White | 820 (61.5) | 558 (61.7) | 262 (61.2) | |
| Black | 257 (19.3) | 179 (19.8) | 78 (18.2) | |
| Hispanic | 226 (17.0) | 149 (16.5) | 77 (18.0) | |
| Other | 30 (2.3) | 19 (2.1) | 11 (2.6) | |
| Body mass index, kg/m2, mean (standard deviation) | 27.4±6.2 | 27.3±6.3 | 27.6±5.8 | 0.38 |
| Hypertension, n (%) | 196 (14.6) | 143 (15.8) | 53 (12.2) | 0.23 |
| Diabetes mellitus, n (%) | 46 (3.4) | 33 (3.6) | 13 (3.0) | 0.52 |
| Hepatitis C virus status | ||||
| Antigen positive | 36 (3.2) | 15 (2.2) | 21 (4.8) | 0.030 |
| Antibody positive | 70 (5.2) | 31 (3.4) | 39 (9.0) | <0.001 |
| Ejection fraction (%) | 61.1±6.5 | 60.9±6.6 | 61.6±6.4 | 0.05 |
| Cause of death | 0.07 | |||
| Anoxia | 479 (35.7) | 320 (35.2) | 159 (36.6) | |
| Cerebrovascular accident | 215 (16.0) | 163 (18.0) | 52 (12.0) | |
| Head trauma | 607 (45.2) | 399 (43.9) | 208 (47.9) | |
| Central nervous system tumor | 6 (0.5) | 3 (0.3) | 3 (0.7) | |
| Other | 35 (2.6) | 23 (2.5) | 12 (2.8) | |
Multivariable analysis of mortality following OHT revealed days on the waitlist (for every 30 days; odds ratio, 1.01 [95% CI, 1.00–1.02], P=0.031) and diabetes mellitus (hazard ratio, 1.87 [95% CI, 1.16–3.02], P=0.011) as independent predictors of mortality (Table 3). The effect of the policy change (hazard ratio, 1.46 [95% CI, 0.76–2.83], P=0.26) on post-transplant survival was not statistically significant. A total of 1129 (84.1%) patients had at minimum 90-day follow-up. Overall survival was comparable between the policy change groups at 90-days (94.25% versus 93.46%, P=0.043; Figure 2). Rates of post-OHT dialysis were 13.8% and 13.4% in the 2 groups (P=0.61; Table 4). As a comparison, rates of postoperative dialysis in all patients undergoing OHT were 12.0% in status 1A patients as compared with 19.2% in status 1/2/3 patients under the new policy. Rates of cerebrovascular accident (2.4 versus 2.1%, P=0.45) and pacemaker insertion (3.4 versus 2.8%, P=0.33) were comparable before and after the policy change. Mortality at 30 (3.1 versus 2.8%, P=0.42), 60 (4.7 versus 3.7%, P=0.40), and 90 (5.7 versus 4.6%, P=0.43) days was also similar.
Table 3.
Multivariable Cox Regression Analysis for Post-Transplant Mortality Following Orthotopic Heart Transplantation Among Patients Bridged With an Intra-Aortic Balloon Pump
| Hazard Ratio | 95% CI | P Value | |
|---|---|---|---|
| Policy change | 1.46 | 0.76–2.83 | 0.26 |
| Days on waitlist (for every additional 30 days) | 1.01 | 1.00–1.02 | 0.031 |
| Diabetes mellitus | 1.87 | 1.16–3.02 | 0.011 |
Figure 2.
Kaplan-Meier survival analysis of outcomes following orthotopic heart transplantation in patients bridged with an intra-aortic balloon pump undergoing surgery before or after the policy change.
Table 4.
Adverse Events Following Orthotopic Heart Transplantation in Patients Bridged With an Intra-Aortic Balloon Pump
| Overall (N=1342) | Pre-Policy Change (N=908) | Post-Policy Change (N=434) | P Value | |
|---|---|---|---|---|
| New-onset dialysis, n (%) | 183 (13.6) | 125 (13.8) | 58 (13.4) | 0.61 |
| Cerebrovascular accident, n (%) | 31 (2.3) | 22 (2.4) | 9 (2.1) | 0.45 |
| Pacemaker, n (%) | 43 (3.2) | 31 (3.4) | 12 (2.8) | 0.33 |
| Length of hospital stay, d, median [IQR] | 16 [11–23] | 16 [12–24] | 16 [11–22] | 0.31 |
| Mortality, n (%) | ||||
| 30-day | 40 (3.0) | 28 (3.1) | 12 (2.8) | 0.42 |
| 60-day | 59 (4.4) | 43 (4.7) | 16 (3.7) | 0.40 |
| 90-day | 72 (5.4) | 52 (5.7) | 20 (4.6) | 0.43 |
| Cause of graft failure, n (%) | 0.039 | |||
| Primary nonfunction | 16 (26.7) | 13 (25) | 3 (37.5) | |
| Acute rejection | 16 (26.7) | 16 (30.8) | 0 | |
| Chronic rejection/atherosclerosis | 11 (18.3) | 11 (21.2) | 0 | |
| Other | 17 (28.3) | 12 (23.1) | 5 (62.5) | |
IQR indicates interquartile range.
Before the policy change, 47.7% of patients who ultimately required IABP support were listed as status 1A and 27.9% were listed as status 1B; following the policy change, 51.5% of were listed as status 1, 8.3% as status 2, and 19.4% as status 3. At the time of transplant, 97.3% of patients requiring IABP support were designated as status 1A as compared with 95.3% as status 2 in the post–policy change era. Examination of all waitlist patients who necessitated IABP support at any time in their treatment course revealed 2263 patients of whom 676 (29.9%) fell after the policy change date (Table 5). Patients with IABPs after the policy change spent fewer days on the waitlist (22 versus 52 days, P<0.001), were more likely to be transplanted (89.8 versus 76.4%, P<0.001), and were less likely to die before transplant (2.3 versus 8.5%, P<0.001). As a comparison, of patients listed as status 1A before the policy change, 74.2% underwent OHT whereas among all patients listed as status 1, 2, or 3 in the new policy, 89.6% underwent OHT. Of those who died while awaiting transplant, hemorrhage was a more common cause of death among post–policy change patients (35.7 versus 5.3%) whereas multisystem organ failure was significantly less common (14.3 versus 33.1%, P=0.010).
Table 5.
Waitlist Outcomes Among Patients Awaiting Orthotopic Heart Transplantation Who Were Bridged With an IABP, Before and After the Policy Change (October 18, 2018)
| Overall, N=2263 | Pre-Policy Change, N=1587 | Post-Policy Change, N=676 | P Value | |
|---|---|---|---|---|
| Reason for removal from waitlist | <0.001 | |||
| Transplanted | 1766 (80.1) | 1212 (76.4) | 554 (89.8) | |
| Refused transplant | 7(0.3) | 7 (0.4) | 0 | |
| Transferred to another center | 7 (0.3) | 7 (0.4) | 0 | |
| Died before transplant | 149 (6.8) | 135 (8.5) | 14 (2.3) | |
| Other | 61 (287) | 52 (3.3) | 9 (1.5) | |
| Condition improved, transplant not needed | 45 (2.0) | 43 (2.7) | 2 (0.3) | |
| Condition deteriorated, too sick for transplant | 162 (7.4) | 126 (7.9) | 36 (5.8) | |
| Transplanted at another center | 3 (0.1) | 1 (0.1) | 2 (0.3) | |
| Patient died during transplant | 2 (0.1) | 2 (0.1) | 0 | |
| Unable to contact candidate | 2 (0.1) | 2 (0.1) | 0 | |
| Cause of death on waitlist | 0.010 | |||
| Infection | 9 (6.1) | 8 (6.0) | 1 (7.1) | |
| Cardiovascular | 32 (21.8) | 29 (21.8) | 3 (21.4) | |
| Cerebrovascular accident | 24 (16.3) | 22 (16.5) | 2 (14.3) | |
| Hemorrhage | 12 (8.2) | 7 (5.3) | 5 (35.7) | |
| Multisystem organ failure | 46 (31.3) | 44 (33.1) | 2 (14.3) | |
| Graft failure | 7 (4.8) | 7 (5.3) | 0 | |
| Other | 17 (11.6) | 16 (12.0) | 1 (7.1) | |
| Days on waitlist | 40 [12–155] | 52 [16–166] | 22 [7–107] | <0.001 |
IABP indicates intra-aortic balloon pump.
DISCUSSION
The shortage of available donor organs, particularly donor hearts, has driven reconsideration of the organ allocation policy to ensure equitable allocation for end-stage heart failure patients. The most recent change in October 2018 increased the priority of patients requiring IABP support, among other changes. Herein, we demonstrate a significant rise in the proportion of patients bridged with an IABP following this policy change. Furthermore, baseline characteristics of pre- and post–policy change recipients were similar though the policy change significantly decreased waitlist time and expanded the geographic distribution of donor organs. These changes do not appear to have negatively impacted early OHT outcomes, with comparable short-term mortality rates in patients undergoing OHT before or after the policy change among those supported with IABPs. These data suggest that bridging to OHT with an IABP is an effective strategy to improve waitlist outcomes without increased post-transplant risk as compared with prior-policy transplants.
One theoretical concern surrounding the policy change was a potential shift in selection of recipients for bridging with IABP use.6 Though we found that the proportion of IABP-bridged patients was increased following the policy change, baseline recipient characteristics remained similar. These comparable baseline characteristics suggest consistency in recipient selection and furthermore expose a pool of recipients who appear to have benefitted from the expanded IABP use. This increased use was also accompanied by broader sharing of organs among patients with IABPs and fewer days on the waitlist. The findings from this policy change are consistent with a prior examination of a 2006 UNOS policy change which also demonstrated expanded organ sharing, decreased waitlist times, and improved waitlist survival.7 This is also supported by a recent study of the 2018 policy change which found improved waitlist outcomes.8
Under the new policy, a greater proportion of waitlist candidates were transplanted, fewer died before transplant, and fewer were deemed too sick to transplant, which supports the goals outlined by UNOS to prioritize patients requiring nondischargeable MCS.1 Among those who died, multiorgan failure was significantly less common, suggesting that improved organ perfusion in select heart failure patients may allow for successful bridging. Though the potential for visceral malperfusion has been cited as an adverse effect of IABP use, innovations in balloon design may potentially result in favorable increases in both mesenteric and renal arterial perfusion.9,10 Accompanying the lower rates of organ failure, we also uncovered an increased percentage of hemorrhage as the cause of death among waitlisted patients. While this may simply reflect a shift away from organ failure as a principal contributor, it is important to consider how this known adverse effect factors into the overall risks/benefits of IABP use. In a study of 481 patients managed with an IABP, complications occurred in 13.1% of patients with the majority of those complications being attributed to severe bleeding.11 Hemorrhagic complications have been associated with older age and longer duration of IABP support, thus these are critical variables to consider in the selection of waitlisted patients for IABP use.11,12
Another important factor to consider is the increasing use of transaxillary approaches in IABP insertion.4,13,14 The primary advantage of transaxillary IABP placement is that it allows patients to be mobile rather than bed-bound.4,14 For patients being bridged to OHT who may need to be supported for weeks depending on organ availability, this becomes increasingly important as it limits the impact of reduced mobility on deconditioning, malnutrition, and infection risk, for example.15,16 Perhaps one rationale for the findings in our analysis is that the above factors could lead to a higher risk of multiorgan failure, which would be mitigated by the improved mobility afforded by transaxillary IABP support. Conversely, the risk of hemorrhage may be higher as transaxillary insertion usually requires surgical cutdown and graft placement onto the axillary artery, although it can also be inserted percutaneously.4,11 Increasing clinical tolerability of IABP use, however, may broaden its appeal at multiple centers such that the influx of patients into status 2 conversely leads to longer wait times.
Some analyses of the policy change have demonstrated improvements in waitlist outcomes but reduced post-transplant survival.8 Our current analysis demonstrates that while the beneficial impact on waitlist outcomes is also observed in the IABP population, we do not observe any detrimental effect on post-transplant survival. Though a prior longitudinal study of OHT recipients suggested worse outcomes associated with IABP use,5 contemporary studies have suggested that it is a safe and efficacious approach for patients awaiting OHT.2,3 Other temporary MCS devices have also been investigated as a bridge. A study of 20 patients undergoing bridge-to-transplant with an Impella device found that 13 (65%) survived to transplant.17 In a larger study of patients bridged with temporary VADs or extracorporeal membrane oxygenation, temporary VAD use was associated with higher, though nonsignificant, rates of transplantation (84.3 versus 78.1%) and significantly increased survival one-year after listing (78.6% versus 54.4%, P=0.002).18 Unfortunately, no randomized studies have compared temporary VADs and IABP use.
Durable LVADs allow for a longer duration of support as well as for outpatient management, thus comparison with IABP use in patients awaiting OHT is often subject to selection bias. One study retrospectively compared durable VAD support with IABPs, finding a comparable post-transplant risk of death between the 2 groups.19 IABP use, however, is associated with lower costs and avoids the need for sternotomy as well as the excess mortality and increased blood transfusions associated with re-operative sternotomy for OHT.20–22 Additionally, recent use of subclavian or axillary placement of IABP may also allow for extended duration of support.4,14,20,23 One study demonstrated a median of 19 days of IABP support (maximum 63 days) with few device-related adverse events; the majority of patients subsequently underwent OHT.14 Another study reported IABP support up to 155 days.24 Given the significantly decreased waitlist time, it is reasonable to consider IABP insertion to preserve the mortality benefit of MCS before OHT while eliminating the need for sternotomy. In addition, under the current allocation system, many groups are favoring IABP insertion and bridging to direct transplantation in patients presenting with decompensated heart failure. This is in contrast to a strategy of durable LVAD support preceding OHT, with the main reason being that durable LVAD bridging has now become much more challenging in terms of donor availability due to priority 4 listing as opposed to priority 2 listing that IABP bridging affords.
This study has several limitations. Given the temporal nature of the policy change, it is plausible that some of the observed differences are attributable to the influence of improved care over time as opposed to an effect of the policy change itself. Additionally, with this study design, we were unable to account for all factors leading to the decision for IABP use, as opposed to inotropes or use of another type of MCS. We were unable to compare long-term outcomes between the pre- and post–policy change patients given the recent nature of this change, thus long-term effects of IABP bridging have yet to be clearly defined. Finally, we could not adjust for device-related adverse events attributable to IABP use which may have negatively impacted survival.
In conclusion, we report on the recipient characteristics, waitlist outcomes, and early OHT outcomes among patients bridged with an IABP. Although in the general OHT population post-transplant survival seems to have declined with the policy change, our analysis suggests that this is not observed in the IABP cohort. Similar to the general OHT population, waitlist outcomes have improved in the IABP group following the policy change. Though the policy change appears to have impacted practice patterns, recipients selected for IABP use are similar suggesting consistency in use patterns. Thus, in patients with end-stage heart failure waitlisted for OHT with appropriate hemodynamic indications, IABP bridging appears to be an effective strategy in the current era.
Supplementary Material
WHAT IS NEW?
A 2018 change to the organ allocation policy increased prioritization of patients awaiting heart transplantation who are bridged with intra-aortic balloon pumps.
In this retrospective study of adult patients undergoing heart transplantation, we found that preoperative balloon pump use increased significantly following the policy change (7%–24.9%).
After the policy change, patients bridged with a balloon pump spent fewer days on the waitlist (15 versus 35 days) and received organs from a greater distance (301 versus 105 miles).
Postoperative outcomes were similar in patients bridged with a balloon pump both before and after the policy change.
WHAT ARE THE CLINICAL IMPLICATIONS?
Balloon pump use has increased significantly following the policy change and postoperative survival is comparable to patients bridged with balloon pumps in the pre–policy change era.
Bridging with a balloon pump appears to increase the proportion of patients who survive to transplant.
One key advantage of balloon pump use over durable left ventricular assist devices is the elimination of the risk associated with redo sternotomy.
Eligible waitlist patients requiring mechanical circulatory support should be considered for balloon pump bridging before heart transplantation.
Sources of Funding
None.
Nonstandard Abbreviations and Acronyms
- IABP
intra-aortic balloon pump
- LVAD
left ventricular assist device
- MCS
mechanical circulatory support
- OHT
orthotopic heart transplantation
- UNOS
United Network for Organ Sharing
Footnotes
Disclosures
Dr Kilic serves on a Medical Advisory Board for Medtronic, Inc. The other authors report no conflicts.
The Data Supplement is available at https://www.ahajournals.org/doi/suppl/10.1161/CIRCHEARTFAILURE.120.006971.
REFERENCES
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