Does subclinical hypothyroidism affect cardiac pump performance? Evidence from a magnetic resonance imaging study.
OBJECTIVE
We sought to assess the effects of subclinical hypothyroidism (SHT) on the cardiac volumes and function.


BACKGROUND
The cardiovascular system is one of the principal targets of thyroid hormones. Subclinical hypothyroidism is a common disorder that may represent "early" thyroid failure.


METHODS
Thyroid profile was evaluated in 30 females with SHT and 20 matched control subjects. Left ventricular end-diastolic volume (EDV) and end-systolic volume (ESV), stroke volume (SV), cardiac index (CI), and systemic vascular resistance (SVR) were calculated by cardiac magnetic resonance (CMR). Regional greatest systolic lengthening (E1) and greatest systolic shortening (E2) were calculated by tagging CMR.


RESULTS
EDV was lower in SHT than in controls (64.3 +/- 8.7 ml/m(2) vs. 81.4 +/- 11.3 ml/m(2), p < 0.001), as well as SV [corrected] (38.9 +/- 7.5 ml/m(2) vs. 52.5 +/- 6.1 ml/m(2), p < 0.001) and CI (2.6 +/- 0.5 l/[min.m(2)] vs. 3.7 +/- 0.4 l/[min.m(2)], p < 0.001). SVR [corrected] was higher in SHT (12.5 +/- 2.5 mm Hg.min/[l.m(2)] vs. 8.6 +/- 1.1 mm Hg.min/[l.m(2)], p = 0.003). The E1 was higher in controls than in SHT at the basal (p = 0.007), equatorial (p = 0.05), and apical (p = 0.008) levels, as well as E2 at the equatorial (p = 0.001) and apical (p = 0.001) levels. All parameters normalized after replacement therapy. A negative correlation between TSH and EDV (p < 0.001), SV (p < 0.001), CI (p < 0.001), and E1 at the apical level (p < 0.001) and a positive correlation between TSH and SVR (p < 0.001) and E2 at the apical level (p < 0.001) were found.


CONCLUSIONS
Subclinical hypothyroidism significantly decreased cardiac preload, whereas it increased afterload with a consequent reduction in SV and cardiac output. Replacement therapy fully normalized the hemodynamic alterations.
Ripoli
Andrea
A
C.N.R. Institute of Clinical Physiology, S. Cataldo Research Campus, Via G. Moruzzi 1, 56124 Pisa, Italy.
Pingitore
Alessandro
A
Favilli
Brunella
B
Bottoni
Antonio
A
Turchi
Stefano
S
Osman
Nael F
NF
De Marchi
Daniele
D
Lombardi
Massimo
M
L'Abbate
Antonio
A
Iervasi
Giorgio
G
D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006352:Heart Ventricles / Q000473:pathology* / Q000503:physiopathology*; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology*; D019028:Magnetic Resonance Imaging, Cine; D008875:Middle Aged; D013318:Stroke Volume / Q000502:physiology*; D013963:Thyroid Hormones / Q000097:blood; D014655:Vascular Resistance / Q000502:physiology*
D013963:Thyroid Hormones