Conduction disorders in the TAVR

How to manage?

Currently, the indication of TAVR in elderly patients with significant and symptomatic aortic stenosis is already a reality, both in private medical practice and in scientific debate tables around the world. However, the complications inherent to the procedure have always been concerns of cardiologists and dealing with this was a great challenge in the face of patients with several comorbidities.

Recently, with the technological advancement of catheters and devices, most of these complications have dropped significantly, but one of them still has high incidences and has a negative impact on the prognosis: the need for a pacemaker.

From the planning of the procedure, we must estimate the risk of the patient needing a pacemaker implantation (PM) and the strongest predictor would be the presence of a right bundle branch block (RBBB). Some other findings such as first degree AV block  or LBBB have been correlated with the same outcome, but they are inconsistent data and require further research.

The presence of RBBB is so predictive that it should even weigh in the indication of conventional intervention in those low risk individuals, given a less than 10% chance of need for PM compared to the 25% of TAVR in the presence of RBBB.

Recently, some services have performed electrocardiographic monitoring for at least 24 hours before the procedure in search of conduction diseases that already indicate the need for a PM implantation, since around 30% of those who implanted it, already had significant disorders prior to TAVR.

During the procedure, some details may increase the risk of the need for PM, such as pre-implantation balloon valvuloplasty. The use of the balloon occurs in more calcified valves and the question remains whether it would be a marker of advanced disease, but the current data suggest that previous ballooning would lead to damage to the conduction system and long-lasting conduction disorders.

The choice of device has an impact on the occurrence of advanced conduction disorders, but in addition, the implant positioning also. First generation self-expanding prostheses had an extremely high need for PM, but currently we have not found such high values. It is true that they are still larger than balloon expendables, but at more acceptable values. Implants 5-7 mm below the aortic annulus led to a greater need for PM, making interventionists look for higher implants to prevent the involvement of the conduction system.

The interruption of chronic use chronotropic drugs before the procedure did not demonstrate any benefit in avoiding the need for PM, even increasing the risk of serious arrhythmic events in the post-intervention.

A post-procedure classification according to the patient’s electrocardiogram has been proposed to stratify the risk of needing PM:

1 – No change in ECG in a patient without RBBB

2 – No change in ECG in a patient with RBBB (<20ms altered in relation to the pre in PR and QRS)

3 – Increase> 20ms in PR or QRS in a patient with RBBB, LBBB, or conduction delays.

4 – New LBBB in the procedure

5 – AV block intermittent or fixed after procedure.

 

For group 1, just one ECG monitoring while in the ICU and one ECG 24 hours later is enough, with the removal of provisional PM wires right after the procedure. This last item differs in group 2, patients with previous LBBB must maintain the provisional PM thread for 24 hours and, being normal afterwards, must follow the same orientation as group 1.

Group 3 is the most challenging and deserves special attention. Since the ECG changes during the procedure in a patient with previous disorders, the maintenance of provisional PM wires is essential. If the new ECG pattern is limited to 240 ms for the PR interval and 150 ms for the QRS and does not progress, discharge from the ICU should be scheduled for 48 hours. If the values are stable, but above 240 ms and 150 ms, it is suggested another day of ICU with the wires still implanted and in case of non-regression, the definitive PM implantation should be performed. In case of progression in any of the situations, the definitive implant must also be performed.

The possibility of electrophysiological study in cases of maintenance for 48 hours of PR> 240 ms and/or QRS> 150 ms is discussed, but since it adds another procedure, this conduct has been avoided nowadays.

Special situations for group 3:

  • For those with PR> 240 ms in isolation and QRS <120 ms, PM implantation is not recommended.
  • Changes (such as those described above) that occur late (> 48h) are rare and, if they occur, should indicate the implantation of definitive PM.

 

Group 4 must remain with the wire of the provisional PM for at least 48 hours in an ICU environment for evaluation. Current evidence shows that approximately 80% of these patients do not have advanced blocks that require definitive PM implantation. Those who do, manifest most often in the first 4 weeks. Therefore, guidance is released from the ICU after 48 hours with removal of the electrodes and monitoring with ECG daily until hospital discharge. Greater vigilance is recommended in the first month after the ECG procedure and more visits to the cardiologist.

In this scenario, requesting monitoring with Holter before hospital discharge can bring some important data or even in some cases, conduct an electrophysiological study for better stratification. However, there is little data on this aspect in the literature. It is worth calling attention to patients with LBBB and QRS> 150ms, as these individuals should probably implant definitive PM.

Group 5 is indisputable and deserves a definitive PM implant, emphasizing that the vast majority of patients who demand an implant manifest this indication still in the procedure room and around 20% until the third day after the implant.

For all groups, in case of regression of the lesion and return to normal, we must follow the guidance of group 2.

Suggested literature:

1 – Rodés-Cabau J, Ellenbogen KA, Krahn AD, et al. Management of Conduction Disturbances Associated With Transcatheter Aortic Valve Replacement: JACC Scientific Expert Panel. J Am Coll Cardiol. 2019; 74 (8): 1086‐1106.

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