Hypothyroidism After the TAVI Procedure in Elderly Patients
Hypothyroidism After the TAVI Procedure in Elderly Patients
Aortic stenosis is highly prevalent in advancing age. The prognosis of this disease has
 dramatically changed with the surgical replacement of the aortic valve and the trans catheter
 aortic valve re-placement (TAVI). The TAVI procedure is also successful in octogenarians and
 frail patients. However, the evaluation before the TAVI procedure requires a high dosage of
 iodinated contrast agent with, consequently, an increased risk for thyroid dysfunction. The
 primary endpoint of this study is to assess, prospectively, the incidence and the predictive
 factors (underlying thyroid disease, medication, food preservative, topical antiseptics) of
 hypothyroidism after a TAVI procedure. The secondary endpoint is the influence of the
 occurrence of hypothyroidism after the TAVI procedure on the geriatric assessment.
Aortic stenosis is highly prevalent in advancing age. The prevalence is 2.5% at an age of 75
 years and 8.1% at an age of 85 years. The estimated mortality after onset of symptoms
 (dizziness, syncope, thoracic pain and dyspnea) with conventional medical treatment is 75%
 after 3 years follow up. The prognosis of this disease has dramatically changed with the
 surgical replacement of the aortic valve. However, an open surgical procedure is not always
 possible in high risk patients for anatomical reasons (sternotomy, radiation and chest
 deformation) or comorbidities defined by the Euroscore and the Society of Thoracic Surgeons'
 risk score (STS score).

 Trans-catheter aortic valve replacement (TAVI) is becoming the standard care of patients
 suffering of non-operable, high risk severe and symptomatic aortic stenosis. The TAVI
 procedure is associated with immediate hemodynamic improvement characterized by a decreased
 aortic valve mean pressure gradient, an improved left ventricular end systolic volume and
 mass, a decreased end ventricular diastolic volume and a better ejection fraction. This
 hemodynamic improvement translates into better clinical outcomes. Mortality rates (2.2% and
 6.7% at one month and at one year) and long term stroke rate are similar after TAVI or
 surgical replacement.

 The TAVI procedure is also successful in octogenarian and in frail patients. Consequently,
 patient's frailty is a growing argument to refer the patient for a percutaneous treatment of
 valve disease instead of a conventional surgical approach.

 The standard evaluation before the TAVI procedure comprises some radiologic studies with
 iodinated contrast agent (coronarography, thoracic CT scanner and the TAVI procedure itself).
 Furthermore, some patients require a treatment with Amiodarone® because of the occurrence of
 atrial fibrillation during the procedure.

 A typical iodinated contrast study confers 13500 µg of free iodine and 15-60g of bound iodine
 (several hundred thousand times above the recommended daily intake). An excess of iodium
 expo-sure can lead to thyroid dysfunction:

 -  Hyperthyroidism particularly in patients with underlying nodular thyroid disease
 (Jod-Basedow effect).

 -  Hypothyroidism in patients with underlying thyroid disease or in patients who are taking
 medication (lithium, amiodarone) which can lead to thyroid dysfunction. The mechanism of
 iodinated contrast agent hypothyroidism is the failure to escape of the acute
 Wolf-Chaikoff effect.

 Amiodarone confers 3-21 mg iodine daily and can also lead to thyroid dysfunction particularly
 in patients with underlying thyroid disease because of the failure to escape of the acute
 Wolf-Chaikoff effect. An autoimmune mechanism is also described.

 Epidemiology In our recent clinical practice (geriatric day hospital UZ Brussel), an
 increased incidence of hypothyroidism in elderly patients after a TAVI procedure has been
 observed. In our knowledge, there are no data about the incidence of hypothyroidism and what
 could be the impact for elderly patients after a TAVI procedure.
Inclusion Criteria:

 -  Provision of signed and dated, written Informed Consent prior to any study specific
 proce-dures

 -  Patient: males and females must be ≥ 70 years old

 -  Patients who will undergo a TAVI procedure

 Exclusion Criteria:

 -  - No obtained signed, dated and written Informed Consent.

 -  Known thyroid dysfunction (for example: Basedow, Hashimoto,...)

 -  Patients receiving any of the following: Lithium, Strumazol or a recent treatment of
 radio-Iode