Aortic stenosis (AS) is a common form of valvular heart disease, the global burden of which continues to increase. Untreated, severe symptomatic AS carries a high mortality rate. Initially performed in patients deemed unsuitable for surgery, and then advancing to become an option for patients with high, intermediate, and now low operative risk, TAVR has revolutionized the treatment of symptomatic severe AS . TAVR is noninferior to surgical aortic valve replacement (SAVR) with regard to mortality at 1 year

2. Introduction
 Aortic stenosis (AS) is a common form of valvular heart disease, the global burden of which
continues to increase.
 Untreated, severe symptomatic AS carries a high mortality rate.
 Initially performed in patients deemed unsuitable for surgery, and then advancing to become an
option for patients with high, intermediate, and now low operative risk, TAVR has revolutionized
the treatment of symptomatic severe AS .
 TAVR is noninferior to surgical aortic valve replacement (SAVR) with regard to mortality at 1 year

3. TAVR Devices
 Currently, the 2 TAVR devices in
clinical use in the United States
are
 Sapien (Edwards Lifesciences, Irvine, CA, USA)
 Evolut (Medtronic, Santa Rosa, CA, USA):
Evolut is a self-expanding, porcine
pericardial tissue valve with a nitinol frame
that is anchored in the supravalvular/supra-
annular position.
 The lower portion of the Medtronic system
sits in the left ventricular outflow tract
(LVOT) and exerts a higher radial force.
 Evolut Pro: The latest generation of this
transcatheter valve is similar in design and
implantation to the Evolut R, but has an
outer wrap of porcine pericardium to help
minimize perivalvular leak
 Sapien 3 valve is a balloon-expandable
system with bovine pericardial tissue
leaflets, a cobaltchromium frame, and lower
fabric skirt that sits in the intravalvular
position

4. Most common Indications for PPM implantation in patients undergoing TAVR
 Complete atrioventricular (AV) block
 Second-degree type II AV block
 Sick sinus syndrome
 Left bundle branch block (LBBB) with first-degree AV block
 Atrial fibrillation with slow response/complete AV block
 Alternating right bundle branch block (RBBB)/LBBB
 Sinus bradycardia

5. PPM implantation Rate
 The rates of post-TAVR conduction
abnormalities requiring a PPM range from
4.3% to 43% with self-expanding valves
associated with a higher rates of PPM
implantation than balloon-expandable
valves.
 Newer valve systems having lower rates
than earlier generation valves
 Self-expanding CoreValve Evolut R has a
PPM rate of 14.7% to 17.4%
 Sapien 3 has a PPM rate of 6.5% to 12.3%
with optimal positioning
 Newest generation Evolut Pro valve
seems to have similar rates of PPM
implantation as the Evolut R

6. MECHANISMS OF CONDUCTION ABNORMALITIES FOLLOWING TAVR
 There is heterogeneity in the location of the AV node, with 50% of patients exhibiting a
predominantly right-sided AV node, 30% with a left-sided orientation, and the remaining 20% of
patients with an AV node running under the membranous septum just below the endocardium.
 The latter 2 anatomic variants may predispose patients to increased risk of conduction
abnormalities following TAVR
 The left bundle branch emerges from beneath the membranous septum and is located within the
interventricular septum, close to the base of the interleaflet triangle that separates the
noncoronary and the right coronary leaflets of the aortic valve.
 This relationship of the left bundle to the aortic root explains why LBBB is the most common
conduction system abnormality following TAVR, as the valve itself can exert direct pressure on
the conduction system

7. Spatial relationship between the 3 cusps of the
aortic valve and the zone where the left bundle branch
emerges beneath the membranous septum

8. MECHANISMS OF CONDUCTION ABNORMALITIES FOLLOWING TAVR
 If LBBB does occur post-TAVR, it appears before hospital discharge in most cases, and
increases the risk of PPM implantation
 It does not appear to increase overall mortality in some studies, although the data are
conflicting, as other studies have suggested an increase in mortality with LBBB post-
TAVR

9. PREDICTION OF CONDUCTION SYSTEM ABNORMALITIES POST TARV
 Preprocedural patient characteristics and peri-procedural considerations are important
predictors for conduction system abnormalities following TAVR.
 In a large meta-analysis that included a mix of balloon-expandable and self-expanding
systems implanted predominantly via the transfemoral approach, male sex,
preprocedural electrocardiographic abnormalities including first-degree AV block,
left anterior hemiblock, and RBBB were significantly associated with the need for
PPM.
 The presence of AV block during the procedure and the use of the self-expanding
prosthesis were also associated with an increased need for PPM.

10. PREDICTION OF CONDUCTION SYSTEM ABNORMALITIES POST TARV
 In an analysis of 9785 patients undergoing TAVR across 229 sites in the United States between 2011 and
2014 as part of the Society of Thoracic Surgeons (STS)/American College of Cardiology Transcatheter
Valve Therapy Registry, patient characteristics associated with higher rates of PPM included increasing
age, higher STS Predicted Risk of Operative Mortality score, previous aortic valve procedures,
chronic lung disease, and the need for home oxygen.
 Electrocardiographic, anatomic, and procedural characteristics associated with an increased need for PPM
were conduction defects on the preprocedural electrocardiogram, larger aortic annulus size and
valve area, need for a larger prosthesis, and the use of valve oversizing
 Preoperative atrial fibrillation, left-posterior hemiblock, LBBB, and ejection fraction
were not associated with the need for PPM

11.  Recent studies have also implicated post TAVR balloon dilation, a method used to treat insufficiently
expanded valves and/or significant perivalvular leak, as a significant predictor of PPM.
 This same study also found PR prolongation greater than 178 ms post-TAVR as an important risk factor for
PPM.
 Depth of the prosthesis within the LVOT, as measured by the mean distance from the annular margin of
the noncoronary cusp to the ventricular end of the prosthesis on computed tomography, is a significant
predictor of PPM implantation.
 Patients requiring a PPM had a mean depth of 9.7 + 4.1 mm, compared with versus 6.3 + 3.4 mm among
patients who did not require a PPM
PREDICTION OF CONDUCTION SYSTEM ABNORMALITIES POST TARV

12.  Most conduction system problems following TAVR occur within the first 48 hours after the
procedure.
 However, a minority of patients may develop late conduction disease. RBBB and an increase in
the PR interval have been identified as independent predictors of delayed advanced conduction
disturbances requiring PPM.
 Preexisting RBBB has been shown to be a predictor of increased cardiovascular mortality after
TAVR as well, and hence such patients need careful follow-up surveillance post-TAVR.

13. MANAGEMENT AND CLINICAL IMPLICATIONS
 The duration of the PR interval has been shown to
peak on post-TAVR days 4 to 6 and the QRS
duration on days 7 to 9.
 Increased PR interval and preexisting RBBB are
reliable predictors of the long-term need for pacing,
whereas LBBB and QRS width is not.
 In the PARTNER registry, the mean time to PPM
implantation was 4.1 days.
 Even among patients who experience high-degree
AV block following TAVR, electrical recovery can
eventually occur in 22% to 56% of patients.
 Increased PR interval and preexisting RBBB
are reliable predictors of the long-term need
for pacing, whereas LBBB and QRS width is
not.
 In patients without a preexisting bundle branch
block or PPM, new RBBB or PPM implantation was
associated with increased all-cause mortality
greater than 1 year from TAVR implantation
 Development of either condition was also
associated with an increased risk of heart failure
hospitalization and reduced left ventricular ejection
fraction
 New LBBB with reduced left ventricular ejection
fraction has been implicated in an increased risk of
sudden death after TAVR

14. Additional Testing and Practical Considerations
 Electrophysiology studies can also be helpful in determining the need for PPM
post-TAVR.
 Ideally, an electrophysiology study would be able to identify those patients who
do not require long-term ventricular pacing.

15. A proposed decision-making algorithm for permanent pacemaker implantation following TAVR

16. Pacing Modes and Pacemaker Types
 Recent studies suggest that the type of pacing used in post-TAVR patients may be important.
 In a multicenter study involving 1621 patients who underwent TAVR, of whom 16.4% received a
PPM, a retrospective analysis was undertaken to determine the effect of various pacing
programming modes on clinical outcomes.
 During a follow-up period of 13 months, 53% of patients were pacemaker dependent (defined as
the absence or inadequate ventricular rhythm >95% of the time on pacemaker interrogation).
 Conventional dual-chamber pacing (DDD) mode was associated with higher rates of
pacemaker dependency compared with other modes aimed at optimizing native
conduction (namely AAI/DDD or VVI modes).

17. Pacing Modes and Pacemaker Types
 Heart failure hospitalizations were significantly increased in the DDD group (81.8% vs 54.6%, P
= .03), and there was a trend to increased overall mortality in this group (73% vs 96%, P = .06)
 Along with pacing modes aimed at encouraging native conduction, cardiac resynchronization
therapy or His-bundle pacing may be options for reducing the risk of heart failure in patients
undergoing TAVR who require a PPM
 Cardiac resynchronization therapy should be considered for patients with a reduced ejection
fraction who will have a high pacer burden and a wide LBBB
 Leadless pacemakers may be an option for elderly or frail patients in whom dual-chamber pacing
is not required and who may not have a high pacemaker burden

18. KEY POINTS
 Conduction abnormalities are common following transcatheter aortic valve replacement
(TAVR), as the anatomy of the left ventricular and aortic outflow tracts predispose to
damage to the conduction system during and after the procedure.
 Patient factors, procedural characteristics, and the type of valve used during TAVR all
contribute to the need for permanent pacemaker.
 Careful monitoring of patients post-TAVR can help identify the patients who will require
a pacemaker and minimize potential deleterious effects.
 A decision-making algorithm incorporating preexisting conduction abnormalities and
electrophysiology testing may improve the appropriate use of permanent pacemakers
post-TAVR.

19. Thank You