Incidence and prevalence of hypothyroidism in patients affected by chronic heart failure: role of amiodarone.
BACKGROUND
It has been demonstrated that hypothyroidism can lead to significant hemodynamic alterations favoring the onset of chronic heart failure (CHF) as well as its progression. Furthermore, amiodarone, an iodine-containing antiarhythmic drug frequently used in CHF patients, is often the cause of primary hypothyroidism.


OBJECTIVE
To define the prevalence and incidence of hypothyroidism in a group of CHF outpatients in stable clinical conditions, with particular reference to the role of amiodarone therapy.


RESULTS
Among the 422 enrolled patients (326 males, aged 65±12 years), 51 (12%) had a previous diagnosis of hypothyroidism while 21 (5%) were newly diagnosed at the enrolment. Then, the overall prevalence of hypothyroidism at the first evaluation was 17%and, as expected, it was significantly higher in females than males (33% vs 13%; p < 0.001). During follow-up (median 28 months) hypothyroidism occurred in further 19 patients (incidence rate: 26/1000/year) and it was mainly attributable to amiodarone therapy. Considering all together the hypothyroid patients, either those affected by thyroid failure at the enrolment than those developing hypothyroidism during the follow-up, levothyroxine therapy was continued or started in 69% of them; however, normal serum TSH values were obtained only in 76% of treated cases (mean levothyroxine dose: 69±44 mcg/day). In any case, in the group of patients affected by hypothyroidism a significantly greater occurrence of heart failure progression was observed.


CONCLUSIONS
Hypothyroidism, especially the subclinical form, frequently occurs in patients affected by CHF receiving amiodarone therapy. Given the unfavorable impact of hypothyroidism on the progression and prognosis of CHF, and the opportunity to adequately manage thyroid failure by means of levothyroxine replacement therapy without the need to withdraw amiodarone, we recommend regular testing of thyroid function in CHF patients, in particular in those submitted to amiodarone therapy, in order to early diagnose a condition of hypothyroidism and titrate substitutive treatment.
Endocrinology and Metabolic Diseases, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy. v.triggiani@endo.uniba.it
Vincenzo
V
Triggiani
Massimo
M
Iacoviello
Fabio
F
Monzani
Agata
A
Puzzovivo
Pietro
P
Guida
Cinzia
C
Forleo
Marco Matteo
MM
Ciccone
Raffaella
R
Catanzaro
Emilio
E
Tafaro
Brunella
B
Licchelli
Vito Angelo
VA
Giagulli
Edoardo
E
Guastamacchia
Stefano
S
Favale
D000368:Aged; D000638:Amiodarone / Q000494:pharmacology* / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology*; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000453:epidemiology* / Q000517:prevention & control; D015994:Incidence; D008297:Male; D008875:Middle Aged; D019338:Polypharmacy; D015995:Prevalence; D013974:Thyroxine / Q000008:administration & dosage / Q000627:therapeutic use
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone; D013974:Thyroxine