CONCLUSIONS
Our study examined outcomes of patients bridged to dLVAD with ECMO for
severe cardiogenic shock, compared to less ill patients bridged with
IABP or no tMCS. ECMO patients had a longer preoperative length of stay,
more frequent mechanical ventilation, higher transaminases, lower
albumin and hemoglobin, higher PCWP, lower PAPi, and more concomitant
procedures. That said, operative and CPB times were similar amongst
groups and reoperation rates were low. The postoperative length of stay
in the ECMO group was slightly longer, though acceptable. We observed
two perioperative ECMO deaths (18%), with exceptionally low early
mortality in the other groups. Differences were not significant, but
this highlights the greater severity of illness in ECMO recipients. Of
note, longer-term outcomes of patients bridged with either form of tMCS
were acceptable and comparable to those with no tMCS.
Use of ECMO as bridge to dLVAD remains controversial, as evidenced by
the recent INTERMACS analysis of Ton et al.2 They
studied 2013-2017 registry data, which included 1138 patients bridged to
dLVAD with ECMO and 3901 bridged with IABP. Their conclusion was that
the exceptional acuity of ECMO-bridged dLVAD patients merits an even
more severe profile (“INTERMACS 0”).
Three-month survival in that study was 76% ECMO, 88% IABP, and 91% no
tMCS, while 12-month survival was 67% ECMO, 79% IABP, and 82% no
tMCS. We observed similar survival in our IABP and no tMCS cohorts
(100% and 94% at 3 months; 88% and 86% at 12 months), but saw
improved survival in the ECMO cohort (81% at 3 and 12 months). They
observed increased early bleeding (19 EPPM) and ischemic CVA (2.8 EPPM)
in ECMO patients. By contrast, our ECMO cohort had an early bleeding
rate similar to that of non-tMCS patients (10.7 and 9.8 EPPM) and lower
than the INTERMACS no tMCS cohort (13.2 EPPM). We observed more early
bleeding (19.9 EPPM), driven by increased GI bleeding (10.7 EPPM), in
the IABP cohort. No early ischemic CVA occurred in ECMO patients,
compared to 2.8 EPPM in the INTERMACS analysis. One early hemorrhagic
CVA occurred in an ECMO patient, for a rate of 3.55 EPPM. Late events
were similarly rare in our analysis, with the exceptions of more
infections in the IABP group and more hemorrhagic CVAs in the no tMCS
group.
Poor ECMO survival in the INTERMACS series is likely driven by the high
prevalence of biventricular support (22% of ECMO patients vs. 5% IABP
and 3% no tMCS). Patients with biventricular support had reduced
3-month (61-69%) and 12-month (50-57%) survival. By comparison, none
of our patients required durable BiVAD. Two patients (1.2%; 1 ECMO, 1
non-tMCS) required temporary RVAD, one of which expired in the
perioperative period.
Similarly, Tsyganenko11 reported a large single-center
series (100 ECMO to dLVAD patients) with 38% operative and 57%
12-month mortality. One third required an RVAD. Shah9described 68 patients bridged with non-IABP tMCS, including 22 ECMO.
They found that ECMO outcomes were similar to non-tMCS INTERMACS 1
patients despite improved hemodynamics and end-organ function in the
ECMO group. In this series, 21% of tMCS and non-tMCS INTERMACS 1
patients required RVAD, vs. 2% of INTERMACS 2-3. Twelve-month survival
was 70% tMCS, 77% non-tMCS INTERMACS 1, and 82% INTERMACS 2-3
(p<0.001).
In contrast, Han2 showed very good 12 month survival
for both ECMO-bridged (78%; N=18) and non-ECMO INTERMACS 1 (88%; N=17;
47% IABP), which they attribute to 46% of patients being transplanted
within <12 months. Our 12-month transplantation rates were
32-41%.
ECMO is our primary tMCS for severe cardiogenic shock because we are a
high-volume (~200 cases/yr) center with protocolized
management. Patients are routinely extubated and
mobilized7,8, allowing rehabilitation prior to dLVAD.
We routinely await renal and hepatic recovery prior to dLVAD, even if it
prolongs ECMO support. Our median ECMO duration was 10 days, and 4
patients (36%) were supported >14 days, all of which
survived to discharge.
We acknowledge this may be contrary to current literature.
Cheng12 reported better early survival in patients
transitioned to durable MCS after <4 days versus longer or not
at all. Tsyganenko11 found >7 days of
ECMO was an independent risk factor for mortality.
Durinka13 reported using longer-duration support (mean
12.1 days) to await normalization of end-organ function before dLVAD.
However, they found much poorer survival for patients supported
>14 days (25% vs. 92% <14 days).
We acknowledge that ECMO is not risk-free. Complications include
bleeding, limb and spinal-cord ischemia, strokes, compartment syndrome,
and cannulation site infection14. However, we believe
some of the morbidity and mortality reported in the above-cited studies
is due to prolonged intubation, which may impair RV function. In the
studies that report mechanical ventilation for ECMO-bridged patients,
the incidence ranges from 59-86% with RVAD usage ranging from
21-29%10,11,15. In our cohort, 2 patients (18%) were
intubated at dLVAD insertion. One of these expired early from multiorgan
failure, and the other required VV ECMO due to persistent hypoxemia.
These patients were supported six and eight days, but may not have been
sufficiently optimized. Finally, one ECMO patient (9%) required an
RVAD. This patient was high risk due to prior chest radiation, three
prior sternotomies, and biventricular dysfunction (pre-ECMO PAPi 1.2).
We also believe standardizing to the LTHS approach improved outcomes in
ECMO-bridged dLVAD recipients. It has been postulated that leaving the
heart in its natural position, avoiding RV compression, and leaving the
pericardium intact reduce post-LVAD RV distention and
failure16. We have previously shown that the LTHS
approach improves outcomes in patients with RV
failure17.
Other studies evaluating minimally-invasive dLVAD for patients in
cardiogenic shock include Wert16, who compared LTHS
HVAD placement to sternotomy in INTERMACS 1 patients. In this series,
≥90% of patients in both groups were on ECMO, and half had prior
cardiac surgery. Seventy percent of LTHS patients remained on ECMO
post-LVAD, for mean 3.5 days. In this very sick cohort, mean ICU stay
was 16, and total hospital stay 31 days (p>0.05 vs.
sternotomy). Significantly fewer LTHS patients required an RVAD (6% vs.
22%), and 3-month (27%) and 12-month (30%) mortality were
significantly better than the 50% mortality at both timepoints in the
sternotomy group.
Sagebin15 compared outcomes for patients on ECMO who
received a Heartmate 3 (Abbott, Abbott Park, IL) via a complete
sternal-sparing (CSS) technique to those implanted via sternotomy.
Median ECMO support was 8 days, and 59% were on mechanical ventilation.
Eighteen percent of CSS patients required an RVAD, vs. 31% of
sternotomy patients (p=0.08). Median ICU stay (12 vs. 11 days) and total
stay (22 vs. 34 days) were similar. Six-month survival was 89% CSS and
68% sternotomy.
The same group18 presented a large series comparing
CSS to sternotomy for Heartmate 3. There was a high prevalence of
INTERMACS 1 (41% CSS, 34% sternotomy) and ECMO (22% CSS, 13%
sternotomy). They found a lower incidence of reoperation for bleeding
(5% vs. 20%) and RVAD use (5% vs. 16%), and shorter median length of
stay (15.5 vs. 21 days) for CSS. Six-month survival was 93% CSS and
77% sternotomy.
Our IABP patients tended toward worse renal and similarly poor RV
function indices as ECMO patients. IABP has been shown not to improve
survival in cardiogenic shock complicating myocardial
infarction19. IABP also does not provide biventricular
support. Our IABP patients had less improvement in creatinine during
tMCS. Their higher incidence of early bleeding may have been partially
due to ongoing congestion and renal dysfunction. However, their overall
survival was excellent and none required an RVAD.
In summary, this report augments the growing body of evidence of
improved outcomes with minimally-invasive dLVAD insertion. High-risk
patients with cardiogenic shock were able to safely undergo LTHS dLVAD
implantation after stabilization with ECMO or IABP, with acceptable
short- and long-term outcomes. Perioperative outcomes and complication
burden were also comparable to a less severely ill cohort who did not
require tMCS.
Author Contributions: Sorensen: concept/design, data
collection, data analysis/statistics, drafting manuscript; Griffith:
concept/design, critical revision; Feller: concept/design, critical
revision; Kaczorowski: concept/design, data analysis, critical revision,
approval.