TAVI -part 3

COMPLICATIONS — Complications of TAVR include shock and low cardiac output during and following deployment, annular rupture, vascular complications, heart block, paravalvular aortic regurgitation, and stroke.

 Shock and low cardiac output during or immediately following TAVR may be triggered by anesthesia, volume depletion, rapid pacing, ischemia, and interruption in cardiac output during valve implantation . Management includes support of systemic blood pressure, inotropic support as needed, ventilatory support with intra-aortic balloon pump support as needed. Elective cardiopulmonary bypass is an option for patients at severe risk for hemodynamic instability.

A rare cause of ischemia is coronary ostia occlusion, which may be treated by percutaneous coronary intervention or coronary artery bypass graft surgery. “Suicide” left ventricle is a rare complication in which left ventricular outflow tract or intracavitary obstruction is precipitated by volume depletion and/or positive inotropic agents and is treated by administration of volume and a beta adrenergic receptor blocking agent.

Aortic annular rupture is a rare life-threatening complication of TAVR . Risk factors include smaller annular size or sinotubular junction, bulky calcification, and aggressive balloon predilation. Management options range from emergent conversion to an open procedure with aortic root replacement to pericardial drainage and autotransfusion of small leaks to comfort care.

 Vascular complications are a frequent early complication of TAVR. For example, in cohort B of the PARTNER trial, vascular complications were significantly more common in the TAVR group than in the standard therapy (including percutaneous valvotomy) group (30.7 versus 5.0 percent)  and in cohort A, vascular complications were more common in the TAVR group than in the surgical group (17.0 versus 3.8 percent)

Risk factors for development of heart block with need for permanent pacemaker implantation include pre-existing right bundle branch block and use of a CoreValve (versus Sapien valve) . In patients receiving the Sapien valve, the risk of this complication (1.8 to 8.5 percent) is similar to that observed following balloon aortic valvotomy or surgical aortic valve replacement. For example, in cohort B of the PARTNER trial, the rate of new pacemaker requirement at 30 days was similar in the TAVR and standard therapy (including balloon valvotomy) groups (3.4 and 5.0 percent)  and in cohort A was also similar in the TAVR and surgical groups (3.8 versus 3.6) . The risk of requiring a permanent pacemaker is higher (ranging from 19.2 to 42.5 percent) in patients receiving the CoreValve 

Post-TAVR aortic regurgitation — Post-TAVR aortic regurgitation includes paravalvular and central (valvular) jets.

Paravalvular aortic regurgitation is common, occurring in about 85 percent immediately post-TAVR. It is caused by incomplete apposition of the prosthesis with the aortic annulus due to inadequate inflation of the prosthesis or calcific deposits that prevent proper valve seating. Causes of paravalvular aortic regurgitation include a heavily calcified annulus, an undersized prosthesis, and an inadequate balloon aortic valvuloplasty prior to deployment of a self-expanding valve,

Paravalvular regurgitation is associated with adverse outcomes. In patients undergoing TAVR in cohort A of the PARTNER trial, at least mild aortic regurgitation was present in about 40 percent of patients and moderate or severe paravalvular aortic regurgitation was identified in approximately 10 percent during follow-up to two years . The presence of more than trace aortic regurgitation was associated with increased risk of late mortality (hazard ratio 2.11; 95% CI, 1.43 to 3.10). However, it remains unclear if mild or moderate aortic regurgitation itself leads to adverse outcomes or whether this finding identifies a higher risk patient subgroup.

Central regurgitation may be caused by improper valve sizing or deployment . Minor valve displacement may resolve gentle probing of the leaflets but severe leaks are an indication for valve-in-valve deployment.

The reported 30-day risk of stroke following TAVR in observational studies and clinical trials is 2 to 5 percent . Observational data have shown similar rates of stroke following transfemoral and transapical TAVR .

Data from the randomized cohort A of the PARTNER trial showed that rates of strokes or transient ischemic attack were significantly higher after TAVR than after surgical AVR at 30 days (5.5 versus 2.4 percent) and at one year (8.7 versus 4.3 percent), and there was a borderline significant trend at two years (11.2 versus 6.5 percent, p = 0.05)
Subclinical brain injury may be substantially more frequent than stroke as suggested by the following studies:

• A diffusion-weighted magnetic resonance imaging (MRI) study that compared 32 patients who underwent TAVR to 21 historical controls treated with surgical aortic valve replacement . New clinically silent cerebral foci of restricted diffusion were significantly more frequent in patients who had undergone retrograde aortic valve implantation than in those who had undergone surgical aortic valve replacement (84 versus 48 percent).
• Similarly high rates of new cerebral ischemic lesions detected by diffusion-weighted MRI were found in a study comparing transfemoral versus transapical TAVR . Similar frequencies of new lesions were found in 19 of 29 (66 percent) patients in the transfemoral group and in 22 of 31 (71 percent) patients in the transapical group. Of note, the patients in the transapical group had a higher frequency of peripheral vascular disease than in the transfemoral group (45 versus 17 percent), although the frequency of aortic plaque ≥4 mm was similar (29 and 28 percent). Most patients (76 percent) with new lesions had multiple lesions (median 3, range 1 to 31). The lesions were largely clinically silent, though one patient in each group had a clinically-evident stroke within 24 hours after the procedure.

Further study is required to determine the clinical significance of these observations. Although most of the new lesions were clinically silent, there is concern that silent cerebral infarcts are associated with subtle cognitive change and with an increased risk of subsequent dementia.

POST-PROCEDURAL CARE

Patients receive intravenous heparin during valve implantation and chronic antithrombotic therapy after implantation. Following implantation of the SAPIEN valve, the following antithrombotic regimen is recommended: dual antiplatelet therapy (aspirin 75 or 100 mg daily plus clopidogrel 300 mg loading dose followed by 75 mg daily) for six months; and after six months, aspirin 75 to 100 mg/day for life.

 Catheter-based aortic valves (Medtronic CoreValve, Edwards SAPIEN valve) have CE mark approval in Europe for patients with high or prohibitive risk for surgical valve replacement. In the United States, the Food and Drug Administration approved the Edwards SAPIEN valve for transfemoral implantation in patients with severe symptomatic native AS who have been determined by a cardiac surgeon to be inoperable for surgical aortic valve replacement and in whom existing co-morbidities would not preclude clinical benefit from correction of the AS

SUMMARY AND RECOMMENDATIONS

• Aortic valve replacement is the mainstay of treatment of symptomatic aortic stenosis (AS). Aortic valve replacement offers substantial improvements in symptoms and life expectancy.
• TAVR has been developed as a treatment for patients with severe symptomatic AS with unacceptably high risk for surgical aortic valve replacement.
• In appropriately screened patients with inoperable severe symptomatic AS, TAVR provides better outcomes compared to medical therapy including percutaneous valvotomy.
• However, TAVR offered no survival benefit compared to standard therapy in patients with an STS score of ≥15 percent because of the high degree of comorbid conditions in these patients.
• In appropriately screened patients with severe symptomatic AS, TAVR and surgical aortic valve replacement are associated with similar rates of one-year survival. However, stroke or TIA and vascular complications are more frequent with TAVR, and major bleeding and atrial fibrillation are more common after surgical valve replacement.
• A multidisciplinary team approach is recommended in approaching high-risk patients with symptomatic AS.

expert consensus document on transcatheter aortic valve replacement
http://www.sciencedirect.com/science/article/pii/S0735109712000022

Comparison of three methods of assessing cardiovascular disability

Class	New York Heart Association functional classification[1]	Canadian Cardiovascular Society functional classification[2]	Specific activity scale[3]
I	Patients with cardiac disease but without resulting limitations of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea, or anginal pain.	Ordinary physical activity, such as walking and climbing stairs, does not cause angina. Angina with strenuous or rapid prolonged exertion at work or recreation.	Patients can perform to completion any activity requiring ≥7 metabolic equivalents, eg, can carry 24 lb up eight steps; do outdoor work (shovel snow, spade soil); do recreational activities (skiing, basketball, squash, handball, jog/walk 5 mph).
II	Patients with cardiac disease resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea, or anginal pain.	Slight limitation of ordinary activity. Walking or climbing stairs rapidly, walking uphill, walking or stair climbing after meals, in cold, in wind, or when under emotional stress, or only during the few hours after awakening. Walking more than two blocks on the level and climbing more than one flight of ordinary stairs at a normal pace and in normal conditions.	Patients can perform to completion any activity requiring ≤5 metabolic equivalents, eg, have sexual intercourse without stopping, garden, rake, weed, roller skate, dance fox trot, walk at 4 mph on level ground, but cannot and do not perform to completion activities requiring ≥7 metabolic equivalents.
III	Patients with cardiac disease resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary physical activity causes fatigue, palpitation, dyspnea, or anginal pain.	Marked limitation of ordinary physical activity. Walking one to two blocks on the level and climbing one flight in normal conditions.	Patients can perform to completion any activity requiring ≤2 metabolic equivalents, eg, shower without stopping, strip and make bed, clean windows, walk 2.5 mph, bowl, play golf, dress without stopping, but cannot and do not perform to completion any activities requiring >5 metabolic equivalents.
IV	Patient with cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms of cardiac insufficiency or of the anginal syndrome may be present even at rest. If any physical activity is undertaken, discomfort is increased.	Inability to carry on any physical activity without discomfort - anginal syndrome may be present at rest.	Patients cannot or do not perform to completion activities requiring >2 metabolic equivalents. Cannot carry out activities listed above (Specific activity scale III).

References:

1. The Criteria Committee of the New York Heart Association. Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels, 9th ed, Little, Brown & Co, Boston, 1994. p.253.
2. Lucien C. Grading of angina pectoris. Circulation 1976; 54:5223.
3. Goldman L, Hashimoto B, et al. Comparative reproducibility and validity of systems for assessing cardiovascular functional class: Advantages of a new specific activity scale. Circulation 1981; 64:1227