Echocardiographic left ventricular functional changes in acute hypothyroidism vs. subclinical hyperthyroidism in patients with differentiated thyroid carcinoma

Introduction: In order to assess echocardiographic left ventricular functional indices in patients with differentiated thyroid carcinoma (DTC), after L-T4 withdrawal (short-term overt hypothyroidism) and during TSH suppressive therapy, we have evaluated cardiac hemodynamics in a single cohort study. Methods: 24 patients with DTC were studied in two phases: 1: at least 4 weeks after L-T4 withdrawal, 2: at least 8 weeks after beginning TSH suppressive therapy. All patients underwent conventional, Doppler and tissue Doppler echocardiography. Results: Although early diastolic mitral inflow velocity (E wave) (p=0.033), and early diastolic velocity of mitral annulus [E(m)] (p < 0.001), were lower in overt hypothyroidism, there were no differences among left ventricular (LV) Dimensions, LV mass and LV mass index , LV Ejection fraction, late diastolic mitral inflow velocity (A wave), E/A ratio, deceleration time(DT), peak systolic velocity of mitral annulus [S(m)], late diastolic velocity of mitral annulus [A(m)], E(m)/A(m) ratio between the two phases. Pulse rate (p < 0.001), LV end diastolic volume (p=0.011) and LV end systolic volume (p=0.003) were higher, while QTc Interval was shorter (p < 0.001) during TSH suppressive therapy. E/E(m) ratio and pulmonary capillary wedge pressure (p=0.042) were higher in hypothyroidism phase. Three patients developed mild pulmonary artery hypertension and 2 of the patients had mild pericardial effusion during TSH suppressive therapy. Conclusion: Short-term overt hypothyroidism or L-T4 suppressive therapy in patients with DTC may have undesirable cardiovascular effects. So in patients with known history of cardiovascular abnormalities, the caring physician should be aware of the cardiovascular complications during hypothyroidism or suppressive therapy.