Feasibility of Transcatheter Aortic Valve Replacement in Low-Risk Patients With Symptomatic, Severe Aortic Stenosis

Trial Objectives: To assess the safety and feasibility of Transcatheter Aortic Valve Replacement (TAVR) with commercially available bioprostheses in patients with severe, symptomatic aortic stenosis (AS) who are low-risk (STS score ≤3%) for surgical aortic valve replacement (SAVR).

Methodology: This is a multicenter, prospective trial of TAVR in low-risk patients at up to twelve sites in the United States. The trial will have three arms. The first will comprise 200 patients undergoing transfemoral TAVR. The second arm will comprise200 closely matched historical controls who underwent isolated bioprosthetic SAVR.

Historical controls will be selected from among patients at the same site who have undergone isolated bioprosthetic SAVR within the previous 36 months. TAVR patients will then be matched to SAVR patients using STS database variables to perform propensity matching, including (but not limited to) age, gender, race, ethnicity, STS score, and valve prosthesis size. Once the historical matched controls are identified, detailed chart review will abstract in-hospital and 30-day outcomes for the SAVR cohort.

The third arm of the trial will comprise a registry of TAVR in up to 100 low-risk patients with bicuspid aortic valve. The results from the registry arm will be analyzed independently.

Primary Efficacy Endpoint: All-cause mortality at 30 days following transfemoral TAVR vs. bioprosthetic SAVR.

Primary Safety Endpoint: Defined as the composite of major adverse events at 30 days:

a. all-cause mortality c. spontaneous myocardial infarction (MI) d. reintervention: defined as any cardiac surgery or percutaneous reintervention that repairs, alters, or replaces a previously implanted aortic valve e. VARC life-threatening bleeding f. Increase in serum creatinine to ≥300% (>3x increase compared to baseline) OR serum creatinine ≥4.0 mg/dL with an acute increase ≥0.5 mg/dL OR new requirement for dialysis g. coronary artery obstruction requiring percutaneous or surgical intervention h. VARC major vascular complication i. cardiac tamponade j. cardiac perforation k. pericarditis l. mediastinitis m. hemolysis n. infective endocarditis o. moderate or severe aortic insufficiency p. significant aortic stenosis q. permanent pacemaker implantation r. new-onset atrial fibrillation

Secondary Endpoints (TAVR Cohort):

• Major adverse cardiovascular and cerebrovascular events (MACCE) at 30 days, 6 months, 12 months, and 2, 3, 4 and 5 years, defined as the composite of:

• all-cause mortality
• stroke
• spontaneous MI
• reintervention
• The occurrence of the individual components of MACCE at 30 days, 6 months, 12 months, and 2, 3, 4, and 5 years (including stoke).
• The composite of major adverse device events post-procedure, and at 6 months, 1 year, and 2, 3, 4, 5 years
• VARC major vascular complications, at 30 days and 1 year
• VARC life-threatening or disabling bleeding, at 30 days and 1 year
• Technical success upon exit from the operating room or catheterization laboratory, defined as all of the following:

• alive
• successful access, delivery, and retrieval of the device and/or delivery system
• correct positioning and successful deployment of the valve
• no need for unplanned or emergency surgery or reintervention related to the device or access procedure, including reinstitution of cardiopulmonary bypass post-weaning for SAVR patients
• Device success at 30 days and 1 year, defined as all of the following:

• absence of procedural mortality
• correct positioning of a single prosthetic heart valve in the proper anatomical location
• device performing as intended:

• No migration, erosion, embolization, detachment, fracture, hemolysis requiring transfusion, thrombosis, or endocarditis 2. Intended performance of the heart valve: no prosthesis-patient mismatch, mean aortic valve gradient <20 mm Hg OR peak velocity <3 m/s, AND no moderate or severe bioprosthetic valve regurgitation 8. Procedural success at 30 days, defined as device success AND no major adverse device events 9. Bioprosthetic valve regurgitation, defined as either moderate or severe aortic regurgitation OR moderate or severe paravalvular leak, at hospital discharge, 12 months, and 2, 3, 4, and 5 years 10. Incidence of new-onset atrial fibrillation at hospital discharge, and at 30 days, 12 months, and 2, 3, 4, and 5 years.

• Conduction disturbance requiring permanent pacemaker implantation at hospital discharge, 12 months, and 2, 3, 4, and 5 years.

• Change in NYHA class from baseline to 30 days, baseline to 6 months, baseline to 12 months, and baseline to 2-5 years.

• Change in distance walked during 6-minute walk test from baseline to 12 months.

• Change in responses to the short form Kansas City Cardiomyopathy Questionnaire (KCCQ-12) from baseline to 12 months.

• Echocardiographic assessment of the bioprosthetic valve post-procedure, at 12 months, and at years 2-5, including (but not limited to):

a. aortic valve mean gradient, maximum gradient, and peak velocity b. calculated aortic valve area c. degree of bioprosthetic valve regurgitation 16. Assessment for subclinical leaflet thrombosis with multislice computed tomography, or transesophageal echocardiography if GFR <50 mL/min/m2, at 1 to 2 months.

• Individual patient level Success all of the following and device success:

• No re-hospitalizations or re-interventions for the underlying condition (e.g., HF)
• Return to prior living arrangement (or equivalent)
• Improvement vs. baseline in symptoms (NYHA Class decrease ≥ 1)
• Improvement vs. baseline in functional status (6MWT increase ≥ 50 meters)
• Improvement vs. baseline in QoL (KCCQ increase ≥ 10)

Number of Trial Sites: 12

Sample Size: 200 consecutive patients and 200 historical controls, and an additional 100 (up to) patients with bicuspid aortic valve

Patient Population: Patients with severe, symptomatic AS who are determined by the Heart Team to be at low surgical risk (STS score ≤3%).

Inclusion criteria

• Severe, degenerative AS, defined as:

• mean aortic valve gradient ≥40 mm Hg OR Vmax ≥4 m/sec AND
• calculated aortic valve area ≤1.0 cm2 OR aortic valve area index ≤0.6 cm2/m2
• Symptomatic AS, defined as a history of at least one of the following:

• dyspnea that qualifies at New York Heart Association (NYHA) class II or greater
• angina pectoris
• cardiac syncope
• The Heart Team, including at least one cardiothoracic surgeon and one interventional cardiologist, deem the patient to be reasonable for transfemoral TAVR with a commercially available bioprosthetic valve
• The Heart Team agrees that the patient is low-risk, quantified by an estimated risk of ≤3% by the calculated STS score for operative mortality at 30 days; AND agrees that SAVR would be an appropriate therapy if offered.
• The Heart Team agrees that transfemoral TAVR is anatomically feasible, based upon multislice CT measurements
• Procedure status is elective
• Expected survival is at least 24 months

For the bicuspid cohort only:

• Aortic Stenosis of a bicuspid aortic valve

Exclusion criteria

• Concomitant disease of another heart valve or the aorta that requires either transcatheter or surgical intervention
• Any condition that is considered a contraindication for placement of a bioprosthetic aortic valve (e.g. patient requires a mechanical aortic valve)
• Aortic stenosis secondary to a bicuspid aortic valve (except for the bicuspid valve cohort)
• Prior bioprosthetic surgical aortic valve replacement
• Mechanical heart valve in another position
• End-stage renal disease requiring hemodialysis or peritoneal dialysis, or a creatinine clearance <20 cc/min
• Left ventricular ejection fraction <20%
• Recent (<6 months) history of stroke or transient ischemic attack
• Symptomatic carotid or vertebral artery disease, or recent (<6 weeks) surgical or endovascular treatment of carotid stenosis
• Any contraindication to oral antiplatelet or anticoagulation therapy following the procedure, including recent or ongoing bleeding, or HASBLED score >3
• Severe coronary artery disease that is unrevascularized
• Recent (<30 days) acute myocardial infarction
• Patient cannot undergo transfemoral TAVR for anatomic reasons (as determined by supplemental imaging studies); this would include inadequate size of iliofemoral access vessels or an aortic annulus size that is not accommodated by the commercially available valves
• Any comorbidity not captured by the STS score that would make SAVR high risk, as determined by a cardiothoracic surgeon who is a member of the heart team; this includes:

• porcelain or severely atherosclerotic aorta
• frailty
• hostile chest
• IMA or other conduit either crosses midline of sternum or is adherent to sternum
• severe pulmonary hypertension (PA systolic pressure > 2/3 of systemic pressure)
• severe right ventricular dysfunction
• Ongoing sepsis or infective endocarditis
• Recent (<30 days) or ongoing bleeding that would preclude treatment with anticoagulant or antiplatelet therapy, including recent gastrointestinal bleeding
• Uncontrolled atrial fibrillation (resting heart rate >120 beats per minute)
• Severe chronic obstructive pulmonary disease, as demonstrated by forced expiratory volume (FEV1) <750 cc
• Liver failure with Childs class C or D
• Pre-procedure shock, inotropes, mechanical assist device, or cardiac arrest
• Pregnancy or intent to become pregnant prior to completion of all protocol follow-up procedures
• Known allergy to warfarin or aspirin