Left ventricular functions in patients with thyroid disorders

ABSTRACT

Cardiac functions in patients with different thyroid disorders are not well studied. The study was addressed to study cardiac dysfunctions especially in subclinical thyroid disorders by a new specific and sensitive imaging, pulsed wave tissue Doppler imaging [PWTDI], which is able to precisely assess the ventricular wall motion. In addition to N-terminal pro-brain natriuretic peptide [N-terminal proBNP]. A new neurohormone, which is a specific and sensitive marker for early detection of left ventricular dysfunctions. We studied 40 patients [29 females and 11 males] with hypothyroidism, 20 of them with overt hypothyroidism [group I], the other 20 patients with subclinical hypothyroidism [group II]. Forty patients [27 females and 13 males] with thyrotoxicosis, 20 of them with overt hyperthyroidism [group III], the other 20 patients with subclinical hyperthyroidism [group IV]. In addition to 20 euthyroid, subjects with age and sex matched [14 females and 6 male] as controls [group V]. The study was performed at Al-Azhar University Hospitals from January 2006 to March 2007. All partners were subjected to full clinical examinations to assess thyroid and left ventricular function, measurements of thyroid profile [FT3, FT4 and TSH] and N-terminal proBNP. All subjects underwent to PWTDI to accurately quantify the global and regional left ventricular function at the posterior septal wall. Left ventricular diastolic dysfunction in the form of impairment of both diastolic relaxation [decreased Ea] and compliance to ventricular filling [decrease Ea / Aa ratio]. LV systolic dysfunction in the form of impaired systolic ejection [decrease Sa]. PWTDI indices show a significant impairment of systolic ejection in all studied groups [P < 0.01] for overt and P< 0.05 for subclinical hypo and hyperfunction] and a delay in diastolic relaxation in overt hypothyroidism [P < 0.01], even those with subclinical hypothyroidism, [P < 0.05] but not impaired in hyperthyroid groups. PWTDI indices showed LV impairment early and significantly than when we used standard 2-D echocardiograms [EF% impaired only in patients with overt thyroid disorders] especially in subclinical groups. In subclinical hypothyroidism LV dysfunction was detected in two patients [10%], using standard 2-D echocardiograms vs. 14 patients [70%], using PWTDI, Sa [P < 0.01] and in 16 patients [80%], using Ea / Aa ratio [P < 0.01] and significantly correlated with FT3, FT4, TSH and N-terminal proBNP. In subclinical hyperthyroidism LV dysfunction was detected in two patients [10%], using standard 2-D echocardiograms vs. 8 patients [40%], using PWTDI, Sa [P < 0.01] and no patients [0%], using Ea / Aa ratio. N-terminal proBNP is highly sensitive and specific with a good positive and negative predicted value for early detection and diagnosis of LV dysfunction especially in subclinical groups and significantly correlated with thyroid profile and PWTDI indices. Left ventricular dysfunction is common in patients with different thyroid disorders even in patients with subclinical thyroid disorders. PWTDI and measurement of N-terminal proBNP are sensitive techniques that allow detection of LV dysfunction, not only in patients with overt thyroid disorders, but also in patients with subclinical thyroid disorders