Effect of central hypothyroidism on Doppler-derived myocardial performance index.
BACKGROUND
Myocardial performance index (MPI) has been used to assess global ventricular function in different types of cardiac disease. Thyroid hormones influence cardiac performance directly and indirectly by changes in peripheral circulation. The aim of this study was to evaluate the possible effect of central hypothyroidism (CH) on MPI.


METHODS
The study included 28 control subjects and 7 patients with CH without cardiac disease. MPI was defined as the sum of isovolumetric contraction time (ICT) and isovolumetric relaxation time divided by ejection time. Patients were submitted to hormonal therapy with thyroxin and the study was repeated after 35 to 42 days.


RESULTS
MPI was significantly higher in patients with CH (0.54 +/- 0.08) than in control subjects (0.40 +/- 0.05) (P =.002). The increase in MPI was caused by the prolongation of ICT without a significant variation of isovolumetric relaxation time and ejection time. After hormonal therapy there was a significant reduction of MPI (0.54 +/- 0.08 vs 0.42 +/- 0.07; P =.028) and ICT.


CONCLUSIONS
MPI was increased in patients with untreated CH. The increase was related to prolongation of ICT and reverted by hormonal therapy.
Doin
Fabio Luiz Casanova
FL
Division of Cardiology, Paulista School of Medicine, Federal University of Sao Paulo, Brazil. fabiodoin@terra.com.br
Borges
Mariana da Rosa
Mda R
Campos
Orlando
O
de Camargo Carvalho
Antonio Carlos
AC
de Paola
Angelo Amato Vincenzo
AA
Paiva
Marcelo Goulart
MG
Abucham
Julio
J
Moises
Valdir Ambrosio
VA
D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D004452:Echocardiography; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D011446:Prospective Studies; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology*; D013974:Thyroxine / Q000627:therapeutic use; D013997:Time Factors; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology
D013974:Thyroxine