Evaluation of right and left ventricular function using pulsed-wave tissue Doppler echocardiography in patients with subclinical hypothyroidism

Estimation of left ventricular functions in patients with subclinical hypothyroidism: a meta-analysis

Objective

To evaluate left ventricular (LV) function in patients with subclinical hypothyroidism (ScH) compared to healthy individuals and to provide clinical hints for practitioners.

Methods

PubMed, Embase, Cochrane Library, and Web of Science were systematically searched in this meta-analysis. Studies evaluating LV function in ScH patients were included. Standardized mean difference (SMD) and the 95% confidence intervals (CIs) were calculated as effect size. Heterogeneity and risks of bias of included studies were assessed.

Results

A total of 9 studies were identified as eligible. The SMD for fractional shortening (FS, %) was -0.21 (95% CI: -0.60, 0.17; z = -1.08, p = 0.2788). The pooled SMD for systemic vascular resistance (SVR, dynes/sec·cm-5) was -0.41 (95% CI: -1.31, 0.49; z = -0.89, p = 0.3744). The pooled SMD for early diastolic mitral flow velocity/late diastolic mitral flow velocity (E/A) ratio was -0.74 (95% CI: -1.09, -0.39; z = -4.13, p < 0.001). The pooled SMD for ejection fraction (EF, %) was -0.35 (95% CI: -0.59, -0.12; z = -2.95, p = 0.0032).

Conclusion

ScH patients had significantly worse LV function parameters than healthy controls. These changes in LV function may be involved in the management of ScH.

The effects of combination treatment with LT4 and LT3 on diastolic functions and atrial conduction time in LT4-treated women with low T3: a short term follow-up study

PURPOSE

To investigate the effects of combination treatment with levothyroxine (LT4) and l- triiodothyronine (LT3) on left atrial volume (LAV), diastolic functions, and atrial electro-mechanical delays in LT4-treated women with low triiodothyronine (T3) levels.

METHODS

This prospective study consisted of 47 female patients between 18 and 65 years old treated at an Endocrinology and Metabolism outpatient clinic between February and April 2022 due to primary hypothyroidism. The study included patients with persistently low T3 levels in at least three measurements, despite LT4 treatment (1.6-1.8 mcg/kg/m²) for 23.13 ± 6.28 months with normal thyrotropin (TSH) and free tetraiodothyronine (fT4) levels. The combination therapy dose was as follows: the fixed LT4 dose (25 mcg) was removed from patients' usual LT4 treatment [100 mcg (min-max, 75-150)], and a fixed LT3 dose (12.5 mcg) was added. Biochemical samples were taken, and an echocardiographic assessment was performed for patients upon their first admission, and after 195.5 ± 12.8 days of receiving LT3 (12.5 mcg) treatment.

RESULTS

There was a statistically significant reduction at left ventricle (LV) end-systolic diameter (27.69 ± 3.14, 27.13 ± 2.89, p = 0.035), left atrial (LA) maximum volume (14.73 ± 3.22, 13.94 ± 3.15, p = 0.009), LA minimum volume (7.84 ± 2.45, 6.84 ± 2.30, p < 0.001), LA vertical diameter (44.08 ± 6.92, 34.60 ± 4.31, <0.001), LA horizontal diameter (45.65 ± 6.88, 33.43 ± 4.51, p < 0.001), LAVI (50.73 ± 18.62, 41.0 ± 13.02, p < 0.001), total conduction time (103.69 ± 12.70, 79.82 ± 18.40, p < 0.001) after LT3 replacement (respectively pre-post- treatment and p value).

CONCLUSION

In conclusion, the findings of this study suggest that the addition of LT3 to LT4 treatment may lead to improvements in LAVI and atrial conduction times in patients with low T3. However, further research with larger patient groups and exploration of different LT4 + LT3 dose combinations is needed to better understand the effects of combined hypothyroidism treatment on cardiac functions.

Atrioventricular Longitudinal Mechanics Using Novel Speckle-Tracking Improved Risk Stratification Beyond Baseline Thyroid Hormone in Asymptomatic Subclinical Hypothyroidism

BACKGROUND

Hypothyroidism is reportedly associated with increased cardiovascular risk and heart failure. We aimed to elucidate the mechanistic influence of atrio-ventricular deformations and their prognostic utilizations in asymptomatic subclinical hypothyroidism (SCH).

METHODS

We assessed speckle-tracking of deformations among 4173 population-based asymptomatic individuals classified as euthyroid (0.25< thyroid-stimulating hormone [TSH] ≤4.0 μIU/mL, n=3799) or having mild (4< TSH ≤10.0 μIU/mL, n=349) or marked (TSH >10 μIU/mL, n=25) SCH. We further related deformational indices to outcomes of atrial fibrillation and heart failure.

RESULTS

Despite borderline differences in indexed left ventricular mass and left atrial volume (P=0.054 and 0.051), those classified as mild and marked SCH presented with modest but significant reductions of global longitudinal strain, and showed elevated E/tissue Doppler imaging (TDI)-e', markedly diminished peak atrial longitudinal strain and higher left atrial stiffness (all P<0.05) when compared with euthyroid subjects. A higher TSH level was independently associated with reduced TDI-s'/TDI-e', worse global atrio-ventricular strains (global longitudinal strain/peak atrial longitudinal strain), elevated E/TDI-e', and worsened left atrial strain rate components (all P<0.05). Over a median 5.6 years (interquartile range, 4.7-6.5 years) follow-up, myocardial deformations yielded independent risk prediction using Cox regression in models adjusted for baseline covariates, N-terminal pro-brain natriuretic peptide, E/e', and treatment effect. Incorporation of global atrio-ventricular strain (global longitudinal strain/peak atrial longitudinal strain) and strain rates further showed improved risk reclassification when added to the baseline TSH strata (classified as euthyroid and mild and marked SCH; all P<0.05). Cox regression models remained significant with improved risk reclassification beyond TSH-based strata by using slightly different deformational cutoffs after excluding marked SCH group.

CONCLUSIONS

Hypothyroidism, even when asymptomatic, may widely influence subclinical atrio-ventricular mechanical functions that may lead to higher heart failure and atrial fibrillation risk. We proposed the potential usefulness and prognostic utilization of myocardial strains in such population.

The association of presystolic wave with subclinical left-ventricular dysfunction in patients with subclinical hypothyroidism

PURPOSE

Subclinical hypothyroidism (SCH) patients develop left-ventricular dysfunction (LVD) in an earlier stage. LVD could be detected with myocardial performance index (MPI), left -ventricular global longitudinal strain (LVGLS), and conventional and tissue-Doppler imaging (TDI). A presystolic wave (PSW) detected on late diastole is associated with LVD. We aimed to determine whether there is an association between PSW and subclinical LVD assessed by different echocardiographic methods in SCH patients.

METHODS

We prospectively enrolled 105 patients diagnosed with SCH in this study. Patients were divided into two groups based on the presence of PSW. Both groups were compared with respect to demographic, clinical, and echocardiographic properties. Multivariable regression analysis was performed to detect predictors of subclinical LVD.

RESULTS

The study included 70 PSW-positive patients (66%, mean age: 50.2) and 35 PSW-negative patients (34%, mean age: 46.5). PSW-positive patients had a lower platelet and a higher RDW level compared to PSW-negative patients. PSW-positive patients had more frequent subclinical LVD, which was assessed by MPI, by conventional and TDI parameters, and by LVGLS. PSW velocity was significantly correlated with MPI velocity (r = 0.31, p = 0.009), TSH level (r = 0.44, p < 0.001), and with LVGLS (r = 0.33, p = 0.005). The presence of PSW was an independent predictor of subclinical LVD in multivariable logistic regression analysis detected with MPI, LVGLS, and TDI parameters (OR = 5.409, p = 0.03; OR = 4.872, p = 0.005; OR = 5.632, p = 0.014, respectively).

CONCLUSION

PSW prevalence was 66% in SCH patients. PSW velocity was significantly correlated with MPI and LVGLS. The presence of PSW was independently associated with subclinical LVD in SCH patients.

Right ventricular diastolic dysfunction and failure: a review

Right ventricular diastolic dysfunction and failure (RVDDF) has been increasingly identified in patients with cardiovascular diseases, including heart failure and other diseases with cardiac involvement. It is unknown whether RVDDF exists as a distinct clinical entity; however, its presence and degree have been shown to be a sensitive marker of end-organ dysfunction related to multiple disease processes including systemic hypertension, pulmonary hypertension, heart failure, and endocrine disease. In this manuscript, we review issues pertaining to RVDDF including anatomic features of the right ventricle, physiologic measurements, RVDDF diagnosis, underlying mechanisms, clinical impact, and clinical management. Several unique features of RVDDF are also discussed.

The subclinical hypothyroid state might predict 30-day readmission in patients admitted with acute heart failure syndrome and reduced left ventricular ejection fraction

INTRODUCTION

Thyroid hormone (TH) has an essential role on the functional capability of cardiac muscle with its gene modulation and induction of vasodilatory effects. There is considerable evidence to suggest the role of TH in patients with acute coronary syndrome, but less is known about its prognostic role in heart failure (HF) patients. We aim to evaluate the association between subclinical hypothyroid state (SCHS) and event rates including 30-day all-cause and HF readmission in patients with an index hospitalization for acute HF syndrome (AHFS).

METHODOLOGY

A retrospective chart review analysis of 2335 patients admitted with the diagnosis of AHFS between 1 January 2007 and 31 December 2017 was conducted. SCHS was defined as thyroid-stimulating hormone (TSH) level >4.50 mIU/L with a normal thyroxine (T₄) level. Patients with pre-existing thyroid disease or receiving thyroid replacement therapy were excluded. HF with preserved ejection fraction (HFpEF) was defined as left ventricular ejection fraction (LVEF) >40% and HF with reduced ejection fraction (HFrEF) was defined as having LVEF ⩽40%. Percentage of 30-day, 3-month and 6-month all-cause readmission and mortality rates were calculated in both cohorts of AHFS (HFpEF and HFrEF) with and without SCHS.

RESULTS

The mean age of the 2335 AHFS population was 65 (±14.8) years. Of the 2335 patients admitted with AHFS, 1228 (52.6%) patients were found to have HFrEF and 1107 (47.4%) with HFpEF. There were 170 (7.3%) patients with AHFS found to have SCHS. There were more males than females (54% versus 46%). The percentage of hospital readmission within 30 days was higher for patients with SCHS compared with those without SCHS in the HFrEF group (42% versus 30%, p = 0.001). Hospital readmission within 30 days for patients with SCHS compared with those without SCHS in the HFpEF group did not differ (36.5% versus 31%, p = 0.47). Additionally, all-cause mortality was higher among patients with SCHS compared with patients without SCHS in the HFrEF group (18.7% versus 7.0%, p < 0.001). All-cause mortality was found similar in both arms of the HFpEF group (9.5% versus 7.7%, p = 0.73).

CONCLUSION

During an index hospital admission for AHFS, SCHS was an independent predictor of readmission in 30 days in patients with HFrEF but not in patients with HFpEF. Additionally, it was related to adverse outcome such as all-cause mortality in HFrEF patients but not in HFpEF patients. Further studies regarding the concept of tissue thyroid and the potential for a therapeutic target are warranted.

Left and right ventricular functions may be impaired in children diagnosed with subclinical hypothyroidism

Subclinical hypothyroidism (SH) may influence both ventricular functions. The aim of this study was to evaluation the findings of Tissue Doppler Imaging (TDI) and other echocardiography modalities in children with SH. We compared left ventricular mass index (LVMI) and TDI parameters of patients with SH and children with euthyroidism. Subclinical hypothyroidism was diagnosed when thyroid stimulating hormone level was higher than the reference value of the laboratory (> 4.2 mIU/L) and free thyroxine level was in normal range. The study included a group of 35 patients with SH and a control group of 38 children with euthyroidism (mean age was 7.6 ± 3.5 years and 9.0 ± 2.4 years, respectively). LVMI was significantly higher in the patient group (p = 0.005). TDI parameters including mitral septal ejection time was lower (p = 0.003) and mitral septal myocardial performance index was higher (p = 0.009) in the patient group. Right ventricular TDI revealed that tricuspid lateral E/Ea and tricuspid septal E/Ea were higher (p = 0.015 and p = 0.024, respectively) and tricuspid septal Ea/Aa and ejection time were lower (p = 0.018 and p = 0.017, respectively) in the patient group. SH may lead to increase LVMI. Left ventricular systolic and diastolic TDI parameters (lower mitral septal ejection time, higher mitral septal myocardial performance index) as well as right ventricular systolic (lower tricuspid septal ejection time) and diastolic (higher tricuspid septal and lateral E/Ea, lower tricuspid septal Ea/Ea) functions may be also impaired in children with subclinical hypothyroidism. TDI is a useful method used for the assessment of the effect of SH on cardiac functions.

Cardiovascular Implications of Diabetes, Metabolic Syndrome, Thyroid Disease, and Cardio-Oncology in Women

Cardiovascular disease may be associated with several comorbidities, including diabetes mellitus, thyroid disorders, and the metabolic syndrome, which are predominantly observed in women and often starting at particular ages. In addition, common treatment options for carcinomas frequently seen in women may induce serious cardiotoxic effects. We review the scope of the problem, the pathophysiologic mechanisms involved, as well as the resulting abnormalities regarding cardiac structure and function as observed by using imaging techniques.

Cardiac autonomic function and vascular profile in subclinical hypothyroidism: Increased beat-to-beat QT variability

BACKGROUND

Patients with subclinical hypothyroidism (SH) may have higher incidence of coronary heart disease and autonomic dysfunction.

DESIGN OF THE STUDY

Prospective case control study.

AIM AND OBJECTIVES

To evaluate beat-to-beat QT variability and vascular stiffness in patients with SH compared to normal controls.

MATERIALS AND METHODS

We compared linear and nonlinear measures of cardiac repolarization liability using beat-to-beat QT intervals derived from the surface electrocardiogram during supine posture and vascular indices including pulse wave velocity and ankle-brachial index (ABI) during supine posture between female patients with SH and age- and sex-matched normal controls. Spectral analysis was done at very low frequency (LF) (0.003-0.04 Hz), Low frequency (LF) (0.04-0.15 Hz), and high frequency (HF) (0.15-0.4 Hz). The HF represents vagal regulation (parasympathetic) and LF represents both parasympathetic and sympathetic regulation.

RESULTS

We recruited 58 women with a mean age of 31.83 ± 8.9 years and 49 controls with mean age of 32.4 ± 9.9 years (P = NS). QT variability index (QTvi) was higher in cases compared to controls (P = 0.01). The ratio of LF/HF of R-R interval which is an index of sympathovagal tone was significantly more in cases compared to controls (P = 0.02). The difference in the left minus the right ABI was significant between cases and controls (P = 0.03).

CONCLUSIONS

The cases had lower parasympathetic activity as compared to controls, and there was a predominance of sympathetic activity in cases. QTvi may be an important noninvasive tool in this group of patients to study the risk of cardiovascular mortality.

The effect of L-thyroxine treatment on left ventricular functions in children with subclinical hypothyroidism

OBJECTIVE

The aim of this study was to search for evidence suggesting treatment for childhood subclinical hypothyroidism (SH) by evaluating left ventricular (LV) functions of children with SH by using M-mode and tissue Doppler echocardiography (TDE).

METHODS

Children with SH and euthyroid healthy children (control group) were enrolled in the study. At baseline and 6 months after euthyroidism was achieved, M-mode and TDE were performed and LV functions were evaluated. Pretreatment parameters of the SH group were compared with those of controls and post-treatment parameters.

RESULTS

31 children with SH and 32 euthyroid healthy children were enrolled in the study. The groups had similar age, gender, puberty and body mass index. Interventricular septum thickness and LV mass index, which are the parameters for LV morphology, were slightly increased in the SH group than in the controls (p<0.05). In TDE, children with SH had significant changes in LV diastolic (lower E'm, higher E/E'm ratio and longer isovolumic relaxation time) and systolic functions (lower isovolumic contraction time) compared with controls (p<0.05). Six months after euthyroidism was achieved, TDE showed a significant improvement of some of the diastolic and systolic parameters (p<0.05).

CONCLUSIONS

The results of this study showed that SH is associated with subclinical alterations in LV function, and LT4 replacement may improve LV systolic and diastolic parameters. However, since SH is usually a self-limiting process, these improvements in LV functions may simply be associated with the natural course of the disease and/or physiological linear growth of the children.

Right ventricular and right atrial function and deformation in patients with subclinical hypothyroidism: a two- and three-dimensional echocardiographic study

BACKGROUND

We sought to investigate right ventricular (RV) function and deformation assessed by three-dimensional echocardiography (3DE) and speckle tracking in patients with subclinical hypothyroidism (SHT), and to evaluate the influence of levothyroxine (L-T₄) therapy on RV remodeling.

METHODS

We included 50 untreated women with SHT and 45 healthy control women matched by age. The L-T₄ therapy was prescribed to all SHT patients who were followed 1 year after euthyroid status was achieved. All study participants underwent laboratory analyses which included thyroid hormone levels, and complete two-dimensional echocardiography (2DE) and 3DE examinations.

RESULTS

3DE RV end-diastolic volume and ejection fraction were significantly reduced in the SHT patients before therapy in comparison with the healthy controls and treated SHT subjects. RV longitudinal strain, systolic, and early diastolic strain rates (SRs) were significantly decreased, whereas RV late diastolic SR was increased in the SHT patients before therapy when comparing with the controls. 2DE speckle tracking imaging revealed that L-T₄ substitution therapy significantly improved RV systolic mechanics, whereas RV diastolic deformation was not completely recovered. Right atrial (RA) function and deformation were significantly impacted by SHT. Replacement L-T₄ treatment improved but did not completely restore RA mechanics in the SHT patients.

CONCLUSION

RV and RA function and mechanics are significantly affected by SHT. L-T₄ therapy and 1-year maintenance of euthyroid status improved but did not completely recover RV and RA function and deformation in the SHT patients, which implies that right heart remodeling caused by SHT is not reversible in a 1-year period.

Subclinical hypothyroidism and myocardial function in obese children

BACKGROUND AND AIMS

Pediatric obesity is an important health problem representing a major public health concern worldwide in the last decades. An isolated elevation of Thyroid Stimulating Hormone (TSH) with normal levels of thyroid hormones is frequently found in obese children. It has been named Isolated Hyperthyreotropinemia or Subclinical Hypothyroidism (SCH) and may be considered a consequence of obesity. Evidence exists that SCH is related to impairment of both systolic and diastolic myocardial function in the adult population. The aim of our study is to establish if obesity-related SCH influences myocardial function in children.

METHODS AND RESULTS

We examined 34 obese children and adolescents with SCH and 60 obese children with normal TSH levels who underwent Doppler echocardiographic to evaluate myocardial function. Global systolic function as assessed by Ejection Fraction (EF) was comparable between groups, however Right Ventricle pressure global systolic function and pressure were significantly reduced in SCH group. Mitral annulus peak systolic (MAPSE) excursion lateral and MAPSE septum resulted significantly reduced in SCH group. Tissue Doppler imaging peak systolic motion (TDI-S) was reduced in SCH group. Diastolic function also showed significant modifications in SCH group.

CONCLUSION

These results suggest possible involvement of cardiac function in obese children with SCH resulting in both abnormal diastolic function and reduced longitudinal systolic function. This new insight into cardiovascular consequences of obesity-related SCH in children could influence clinical approach to such patients by pediatric endocrinologists.

Endothelial dysfunction and subclinical hypothyroidism: a brief review

Subclinical hypothyroidism (SH) is characterized by normal serum free T4 and free T3 levels and increased serum TSH levels. The relationship between SH and cardiovascular diseases has been one of the most popular topics recently. There is still some controversy concerning the cardiovascular impact of SH and management protocols. The vast majority of the studies published so far, suggests that SH accelerates endothelial dysfunction through traditional effects on risk factors that promote atherosclerosis and nontraditional effects on vasculature. In particular, SH is associated with increased of LDL-cholesterol, diastolic blood pressure, and markers of chronic inflammation (C reactive protein) and simultaneously reduces the bioavailability of nitric oxide to blood vessels and increases the expression of angiotensin receptor. Furthermore, replacement therapy seems to improve all these aspects.

Subclinical hypothyroidism effects on cardiac function

To evaluate heart function in subclinical hypothyroid women in comparison with healthy subjects, a prospective study was performed on newly detected subclinical hypothyroid women presenting to endocrinology clinic of Tabriz Sina Hospital from October 2007 to February 2008. Thirty five women with Subclinical Hypothyroidism (SH) in case group were matched with 35 healthy euthyroid women in control group. All patients in both groups were studied by two dimensional echocardiography and Tissue Doppler Imaging (TDI) in Tabriz Shahid Madani Hospital. The FT4 and TSH levels were measured. Comparison of TDI results in Right Ventricle (RV) showed the significantly lower mean T(v) excursion in case group with no significant difference in other parameters. In Left Ventricle (LV), the mean A(m), A(v) and E(v)/E(m) were significantly higher and E/A was lower in the case group, but there was no significant difference in other parameters. No RV diastolic dysfunction was documented in both groups. There was no case with LV systolic dysfunction in both groups. There were 21 (60%) patients with LV diastolic dysfunction in the case group comparing with 11 (31.4%) cases in the control group (p = 0.016, OR = 0.306). Frequency of LV diastolic dysfunction was significantly higher in the case group in patients aged > or = 40 years (94.1% vs. 53.3%; p = 0.013). There was no case of pericardial effusion in the studied population. According to our results, SH may cause LV diastolic dysfunction. Likewise, minor RV systolic dysfunction might be seen in these patients.

Subclinical hypothyroidism: the state of the art

Subclinical hypothyroidism (SH) is a common clinical problem, particularly in adulthood and the elderly. Its prevalence is conditioned by several etiological and risk factors. The highest age- and sex-specific rates are in women over 60. SH may be associated with manifestations of mild thyroid failure, which may reverse under levothyroxine (L-T4) therapy. The risk of progression to overt hypothyroidism is distinctly higher in cases with underlying thyroid disease. A population routine screening is not generally recommended, but screening is encouraged in high-risk groups. L-T4 therapy may be indicated in subjects with TSH levels which are repeatedly and consistently elevated (>10 microIU/ml) and may be considered in those with TSH ranging between 4.5-5.5 and 10 microIU/ml, particularly if anti-thyroid antibodies are positive and/or hypothyroid symptoms are present. Treatment should be based, at least initially, on L-T4 low doses.

Thyroid stimulating hormone and left ventricular function

CONTEXT

Overt hypo- and hyperthyroidism are associated with cardiac disease, whereas this relation is more uncertain regarding subclinical thyroid dysfunction.

OBJECTIVE

The objective was to assess the relation between serum TSH level and cardiac function.

DESIGN

We conducted a cross-sectional epidemiological study and a nested case-control study.

SETTING

The study was performed at a university hospital.

SUBJECTS

A total of 2035 subjects were included in the epidemiological study and 204 subjects in the nested case-control study (serum TSH < 0.50, 0.50-3.49, and 3.50-10.0 mIU/liter in 20, 118, and 66 subjects, respectively, all with normal serum free T(4) and free T(3) levels).

MAIN OUTCOME MEASURES

Left ventricular mass by body surface area (LVMI) and indices of left ventricular function, as assessed by conventional and pulsed-wave tissue Doppler (PWTD) echocardiography, were recorded.

RESULTS

No significant relation was found between serum TSH level and LVMI. In the nested case-control study, the subjects with serum TSH 3.50-10.0 mIU/liter had no signs of cardiac dysfunction. However, the PWTD data showed higher velocities at all measurement sites in the subjects with serum TSH less than 0.50 mIU/liter as compared with the euthyroid group.

CONCLUSIONS

With the possible exception of overt hypo- and hyperthyroidism, there is no significant association between serum TSH level and LVMI. Subjects with subclinical hypothyroidism, in whom the mean serum TSH level is slightly above the reference range, appear to have normal cardiac function, whereas subjects with serum TSH levels less than 0.5 mIU/liter appear to have changes in myocardial velocities detected by PWTD.

Effects of thyroxine therapy on right ventricular systolic and diastolic function in patients with subclinical hypothyroidism: a study by pulsed wave tissue Doppler imaging

INTRODUCTION

The effects of l-thyroxine (l-T(4)) replacement for subclinical hypothyroidism (SH) on right ventricle (RV) functions has not been previously studied by means of pulsed wave tissue Doppler imaging (PWTDI). We investigated the effects of l-T(4) therapy on RV function in patients with SH using PWTDI.

PATIENTS AND METHODS

Fifty-three patients with newly diagnosed SH and 25 controls were evaluated by standard echocardiography and PWTDI. After euthyroidism was restored by l-T(4), measurements were repeated. Myocardial systolic wave (S(m)) velocity, isovolumic acceleration (IVA), myocardial precontraction time (PCT(m)), and PCT(m) to contraction time (CT(m)) ratio were calculated as systolic indices. Early (E(m)) velocity, late (A(m)) velocity, E(m) to A(m) ratio, and myocardial relaxation time (RT(m)) were determined as diastolic measurements.

RESULTS

S(m) was similar in patients and controls, whereas IVA was significantly lower in patients with SH (P < 0.001). SH patients had significantly decreased E(m) velocity, whereas A(m) velocity and E(m) to A(m) ratio did not differ. PCT(m) and RT(m) were significantly longer, and PCT(m) to CT(m) ratio was significantly higher in patients (P = 0.002, P = 0.002, P < 0.001, respectively). S(m) velocities were similar before and after l-T(4) replacement, whereas IVA significantly increased after therapy (P < 0.001). E(m) tended to increase (P = 0.05), whereas A(m) and E(m) to A(m) ratio were not changed. PCT(m), PCT(m) to CT(m) ratio, and RT(m) decreased significantly (P < 0.001 for all).

CONCLUSIONS

SH is associated with RV systolic and diastolic dysfunction, and l-T(4) treatment improves these abnormalities. PWTDI, especially IVA, may be a suitable tool for the early detection of RV systolic dysfunction.

Effect of L-thyroxine treatment on left ventricular function in subclinical hypothyroidism

Aim of this study was to investigate the effects of thyroxine treatment on myocardial regional left ventricular (LV) systolic and diastolic function in patients with subclinical hypothyroidism (SH) by tissue Doppler imaging (TDI). Forty-two patients (29 women and 13 men; mean age 52.2+/-15.1 years) with SH, as judged by elevated serum thyroid-stimulating hormone (TSH) levels (>3.6 mIU/l; range, 3.8-12.0) and free thyroid hormones (FT4 and FT3) within the normal range, and 30 euthyroid volunteers (21 women and nine men; mean age 50.4+/-17.1 years) underwent standard echocardiography and TDI-derived early (Em) and late (Am) diastolic velocities, systolic (Sm) velocity, and isovolumetric relaxation time (IVRTm). Patients were randomly assigned to receive or not L-thyroxine replacement therapy. All patients returned after 6 months to repeat thyroid function tests and the evaluation of all parameters. No significant differences were seen in the Sm peak between SH and control groups. Respect to controls, SH patients exhibited a lower Em, a higher Am, and, subsequently, a reduced Em/Am ratio of both lateral wall (LW) and interventricular septum (IVS) (P<0.001 for both). The IVRTm was distinctly longer in SH patients, as compared to controls (P<0.001). At 6 months, L-thyroxine-treated patients showed a significant increase of Em (P<0.01) and a subsequent increase of the Em/Am ratio (P<0.01), whereas IVRTm significantly reduced (P<0.05). No significant change in any of these parameters was observed in the untreated group. Our data suggest that SH is associated with a subtle, reversible impairment of myocardial function. TDI analysis detects and extends these functional defects by displaying alterations in regional myocardial function. L-T4 replacement therapy should be advised for these patients with the aim to correct preclinical cardiac dysfunction and prevent the development of clinically significant myocardial dysfunction.