Impact of the United Network for Organ Sharing allocation criteria changes on temporary mechanical circulatory support use as a bridge to transplant

Table 1 Mechanical circulatory support and transplant status over the years

1989-1998, status	1999-2018, status	2018-present, status	Criteria
1	1A	1	VA-ECMO1
			Non-dischargeable surgically implanted BiVAD
			MCSD with life threatening ventricular arrythmias
		2	Non-dischargeable surgically implanted LVAD
			TAH, BiVAD, RVAD
			Malfunctioning MCSD
			Percutaneously inserted MCSD1
			IABP1
			VT/VF
		3	Dischargeable LVAD (during 30-day discretionary period)
			Multiple inotropes or single high dose inotrope with hemodynamic monitoring1
			MCSD with either hemolysis, thrombosis, right heart failure, mucosal bleeding or aortic insufficiency
			VA-ECMO after 7 days
			Non-dischargeable surgically implanted LVAD after 14 days
			Percutaneously inserted MCSD after 14 days
			IABP after 14 days
	1B	4	Dischargeable LVAD (without 30-day discretionary period)
			Inotropes (without hemodynamic monitoring)
			Congenital heart disease
			Ischemic heart disease with intractable angina
			Amyloidosis/Hypertrophic/Restrictive cardiomyopathy
			Heart re-transplant
2	2	5	Dual organ transplant candidates on waitlist
		6	All other candidates

¹Indicates that patients will also need to meet invasive and non-invasive hemodynamic criteria for cardiogenic shock to be listed under this status. VA-ECMO: Veno-arterial extracorporeal membrane oxygenation; BiVAD: Bi-ventricular assist device; MCSD: Mechanical circulatory support device; LVAD: Left ventricular assist device; RVAD: Right ventricular assist device; TAH: Total artificial heart; IABP: Intra-aortic balloon pump; VT: Ventricular tachycardia; VF: Ventricular fibrillation.

Table 2 Summary of important temporary mechanical circulatory support devices

Device	Insertion method	Ventricular support	LV unloading	Cardiac output increase (L/min)	Oxygenation	Pump mechanism	Insertion location	Location of device	Cardiac synchronization	Mandatory anticoagulation	Durability	Ambulation possibility (If yes, not commonly performed)	FDA approval for BTT	Major contraindications	Major adverse events
IABP	Percutaneous	Left	Indirect	0.5	No	Pneumatic	Femoral or axillary artery	Proximal descending aorta	Yes	No, but recommended	Days	Yes if subclavian approach	No	Significant AI, aortic dissection, PVD	Limb ischemia, bleeding, vessel injury, aortic rupture, thrombocytopenia
Impella CP	Percutaneous	Left	Yes	3-4	No	Axial	Femoral or axillary artery	Across aortic valve	No	No with BBPS1, but recommended	Approved for ≤ 4 days	Possible with axillary approach	No	Significant PVD, AI, VSD, metallic aortic valve	Limb ischemia, valve injury, hemolysis, bleeding, ventricular arrhythmia
Impella 5.5	Surgical cutdown	Left	Yes	6	No	Axial	Axillary artery or directly into aorta	Across aortic valve	No	No with BBPS1, but recommended	Approved for upto 14 days; Often used for days to few weeks	Possible with axillary approach	No	Significant PVD, AI, VSD, metallic aortic valve	Limb ischemia, valve injury, hemolysis, bleeding, ventricular arrhythmia
Impella RP	Percutaneous	Right	Yes	4	No	Axial	Femoral vein	Pulmonary artery	No	Yes	Approved for upto 14 days. Often used for days to few weeks	Possible with axillary approach	No	Disorders of pulmonary artery wall, mechanical valves, PVD, mural thrombus of right atrium	Bleeding, vascular complication, hemolysis, thrombus, valve injury, arrhythmia
VA-ECMO	Percutaneous	Left, right, or both	No	10	Yes	Centrifugal	Femoral artery, femoral vein, internal jugular vein, or central cannulation	Extracorporeal	No	Yes	Approved for 6hrs	Yes, with portable ECMO devices	No	AI, aortic dissection, LV thrombus, severe PVD	Vascular injury, limb ischemia, stroke, intracranial hemorrhage
Centri-Mag VAD	Surgical	Left, right, or both	Yes	10	Yes- with oxygenator	Centrifugal	Left ventricle/Right superior pulmonary vein, Aorta	Extracorporeal	No	Yes	Weeks to months	Yes	No	AI, aortic dissection, LV thrombus, severe coagulopathy	Bleeding, thrombus, infection, stroke
Tandem Heart pVAD	Percutaneous	Left	Yes	5	No	Centrifugal	Femoral artery and vein, requires transseptal puncture	Femoral artery	No	Yes	Approved for upto 6 hours	No	No	AI, PVD, known atrial thrombus	Vascular injury, limb ischemia, stroke, intracranial hemorrhage
Tandem Heart Protek Duo	Percutaneous	Right	No	4.5	Yes- with addition of oxygenator	Centrifugal	Internal jugular vein	Right atrium to pulmonary artery	No	Yes	Approved for 6 days, used weeks to months	Yes, if internal jugular access	No	Severe PVD, severe pulmonary hypertension	Bleeding, vascular complications, thrombus, hemolysis
Syncardia TAH	Surgical	Both (total heart replacement)	Not applicable, device replaces both ventricles	7-9	No	Pneumatic	Device directly attached to atria	Fully implantable	No	Yes	Months to years	Yes	Yes	Severe systemic illness, coagulopathy, inadequate body size	Stroke, infection, thromboembolism, device malfunction

¹Heparin-free bicarbonate-based purge solution. VA-ECMO: Veno-arterial extracorporeal membrane oxygenation, VAD: Ventricular assist device, TAH: Total artificial heart, IABP: Intra-aortic balloon pump; AI: Aortic insufficiency; PVD: Peripheral vascular disease; VSD: Ventricular septal defect; LV: Left ventricle; pVAD: Percutaneous ventricular assist device.

Table 3 Currently identified attributes as well as attributes in discussion in the 2024 OPTN concept paper for continuous allocation system for heart transplant

	Medical urgency	Post-transplant survival	Candidate biology	Patient access	Placement efficiency
Currently identified attributes	Type of tMCS; Inotrope use; LVAD use; HCM, RCM, CHD; Re-Tx; IHD w angina; Multi-organ Tx		Blood type; Sensitization using CPRA	Pediatric recipients; Prior living organ donors	Geographic proximity; Proximity efficiency
Attributes still in discussion	Waiting time accrued with an LVAD (increased risk of complications with time)	Post-transplant survival metric	Abnormal stature

HCM: Hypertrophic cardiomyopathy; RCM: Restrictive cardiomyopathy; Tx: Transplant; IHD: Ischemic heart disease; CPRA: Calculated panel reactive antibody.