Cardiac amyloidosis and aortic stenosis
Coexisting diseases in the elderly?
Aortic stenosis is the most common valve disease in the elderly in developed countries and evolves, in advanced stages, with concentric myocardial hypertrophy. This is the same age group with the highest prevalence of senile amyloidosis and a similar clinical presentation can make diagnosis a challenge. Cardiological involvement is due to the infiltration of cardiac structures by genetically unchanged transthyretin amyloid fibrils leading to increased myocardial thickness, diastolic dysfunction and loss of contractile capacity in late stages.
We can also find infiltration in the aortic valve and this could speed up the process of calcification and reduce the mobility of the leaflets. When the atrial wall is affected, we find a high prevalence of supraventricular arrhythmias, worsening the symptoms in these cases.
Some series of patients report concomitance of pathologies in up to 16-20% and in the presence of both pathologies, the patient has a worse prognosis than when he is affected in isolation, but we still need more data to understand the real impact of this on the long-term survival. Currently, treatments for transthyretin amyloidosis already exist, but the standardization to define those who will receive this treatment is still unclear.
The suspicion of the presence of amyloidosis in a patient with aortic stenosis comes through some echocardiographic aspects. The presence of an S ‘wave smaller than 6 cm/s in the mitral annulus associated with a reduced longitudinal strain profile with preservation only in the apical region are very suggestive of the presence of cardiac involvement due to amyloidosis. We have a higher prevalence of patients with low gradient aortic stenosis in this population, raising the suspicion of concomitance.
The clinical treatment of amyloidosis often becomes a challenge in these patients, since in general we have the indication for the use of diuretics and vasodilators, as well as beta-blockers, which can make aortic stenosis symptomatic before surgical correction. Thus, these patients are very symptomatic before the calcified aortic valve is approached. The risk of thromboembolic events is higher due to amyloid involvement and anticoagulation should be indicated in the presence of supraventricular arrhythmia or intracavitary thrombi.
Another frequent complication in these patients is AV block due to infiltration in the conduction system. Patients with first-degree AVB and a history of syncope should be thoroughly investigated for pacemaker deployment. Similarly, those who are going to undergo TAVR, have a high incidence of need for PM implantation.
The treatment of aortic stenosis must be followed even in the presence of cardiac involvement by amyloidosis, keeping in mind the worst evolutionary prognosis. Some clinical and laboratory situations raise the suspicion of a worse prognosis and should be taken for discussion with the Heart Team. They are:
- LVEF <50%
- Longitudinal strain <10%
- Diastolic dysfunction> III
- Stroke volume <30mL/m2
In these cases, the final opinion of the Heart Team is essential to indicate or contraindicate the intervention in this group of patients, given the higher prevalence of futile treatments in this scenario. In the case of contraindication to valve replacement, treatment for HF and the use of tafamidis should be instituted to try to slow the progression of the condition.
Some studies suggest that TAVR would be more indicated for being less aggressive to the patient, even though they know that the need for pacemaker deployment is greater with this interventionist therapy.