The Heart and Thyroid Disease

Tachycardia in hyperthyroidism: Not so common

Objective

The commonly held association of hyperthyroidism with sinus tachycardia and widened pulse pressure (PP) has not been reassessed in decades despite patients with hyperthyroidism in current practice not always present with these signs. The study objective was to assess prevalence and variability of sinus tachycardia and widened PP in present day among individuals with different degrees of hyperthyroidism.

Methods

Data was collected retrospectively from 248 adult patients in an outpatient setting with biochemical evidence of hyperthyroidism, recorded heart rate (HR) and blood pressure (BP) who were not treated with medications that can influence these parameters.

Results

Mean age was 42.0 ± 14.2 years with 66.9% being female. Median free thyroxine (fT4) level was 3.49 (IQR 2.42–4.58) ng/dL and thyroid stimulating hormone (TSH) 0.02 (IQR 0.01–0.03) mIU/L. Tachycardia, defined as HR >100 bpm, was present in 28.2%. In the lowest and highest fT4 quartiles, tachycardia was present in 16.4% and 38.7% respectively. Using logistic regression, tachycardia was associated with higher fT4 and diastolic BP. More lenient outcome of tachycardia with HR >90 bpm was seen in 47.2%. Widened PP, defined as >50 mmHg, was observed in 64.1% of patients and correlated with higher fT4 and BP.

Conclusions

Tachycardia is not a common feature of hyperthyroidism today. The relatively infrequent finding of tachycardia in this study compared to older studies may reflect differences in the way medicine is practiced today. The increased ordering of thyroid function tests most likely unmasked cases of mild or asymptomatic thyrotoxicosis. A widened PP was a more prevalent clinical finding in this study.

Overt and subclinical hypothyroidism: who to treat and how

Hypothyroidism denotes deficient production of thyroid hormone by the thyroid gland and can be primary (abnormality in thyroid gland itself) or secondary/central (as a result of hypothalamic or pituitary disease). The term 'subclinical hypothyroidism' is used to define that grade of primary hypothyroidism in which there is an elevated thyroid-stimulating hormone (TSH) concentration in the presence of normal serum free thyroxine (T4) and triiodothyronine (T3) concentrations. Subclinical hypothyroidism may progress to overt hypothyroidism in approximately 2-5% cases annually. All patients with overt hypothyroidism and subclinical hypothyroidism with TSH >10 mIU/L should be treated. There is consensus on the need to treat subclinical hypothyroidism of any magnitude in pregnant women and women who are contemplating pregnancy, to decrease the risk of pregnancy complications and impaired cognitive development of the offspring. However, controversy remains regarding treatment of non-pregnant adult patients with subclinical hypothyroidism and serum TSH values ≤10 mIU/L. In this subgroup, treatment should be considered in symptomatic patients, patients with infertility, and patients with goitre or positive anti-thyroid peroxidase (TPO) antibodies. Limited evidence suggests that treatment of subclinical hypothyroidism in patients with serum TSH of up to 10 mIU/L should probably be avoided in those aged >85 years. Other pituitary hormones should be evaluated in patients with central hypothyroidism, especially assessment of the hypothalamic-pituitary-adrenal axis, since hypocortisolism, if present, needs to be rectified prior to initiating thyroid hormone replacement. Levothyroxine (LT4) monotherapy remains the current standard for management of primary, as well as central, hypothyroidism. Treatment can be started with the full calculated dose for most young patients. However, treatment should be initiated at a low dose in elderly patients, patients with coronary artery disease and patients with long-standing severe hypothyroidism. In primary hypothyroidism, treatment is monitored with serum TSH, with a target of 0.5-2.0 mIU/L. In patients with central hypothyroidism, treatment is tailored according to free or total T4 levels, which should be maintained in the upper half of the normal range for age. In patients with persistently elevated TSH despite an apparently adequate replacement dose of LT4, poor compliance, malabsorption and the presence of drug interactions should be checked. Over-replacement is common in clinical practice and is associated with increased risk of atrial fibrillation and osteoporosis, and hence should be avoided.

Hypertension in the elderly

Many elderly patients have hypertension, although it is more likely to go untreated in this population. Treatment goals are the same in elderly patients as in younger patients, but elderly patients are more likely to have multiple comorbidities, which must be factored into treatment plans. This article highlights the unique challenges in treating this population.

Thyroid hormones and cardiac arrhythmias

Thyroid hormone plays an important role in cardiac electrophysiology and Ca2+ handling through both genomic and nongenomic mechanisms of action, while both actions can interfere. Chronic changes in the amount of circulating thyroid hormone due to thyroid dysfunction or systemic disease result in structural, electrophysiological and Ca2+ handling remodeling, while acute changes may affect basal activity of cardiac cells membrane systems. Consequently, long-term or rapid modulation of sarcolemmal ion channels, Ca2+ cycling proteins and intercellular communicating channels by thyroid hormone may affect heart function as well as susceptibility of the heart to arrhythmias. This aspect including pro- and anti-arrhythmic potential of thyroid hormone is highlighted in this review.

[Cardiothyrotoxicosis in the young adult in Marrakech. A report of 36 cases]

Thyrotoxicosis is underdiagnosed because of its low occurrence in series from Africa. The aim of this study was to evaluate the frequency, the demographic data, and the etiological aspects of thyrotoxicosis among hyperthyroidy. Thirty-six patients with thyrotoxicosis (group I) gathered during a period of four years was analysed, as well as 180 hyperthyroidy cases (group II). Cardiothyrotoxicosis was observed with a frequency of 16.6%. The mean age was respectively of 44.5+/-13.3 versus 32.8+/-11.4 years (p<10(-6)). Cardiothyrotoxicosis was related to multinodular goitres (18 cases), a Basedow disease (14 cases), a toxic adenoma (four cases), while the principal cause of hyperthyroidy was toxic adenoma followed by the Basedow disease (72 cases, 40%). Different modes of presentation of cardiothyrotoxicosis were found: cardiac heart failure in 27 cases (75%), permanent atrial fibrillation in 22 cases (61.1%), atrial flutter in two cases, coronary insufficiency in four cases, ventricular extrasystoli (trigeminism) in two cases, second auriculoventricular block in two cases, dilated myocardiopathy in 10 cases (27.7%), ischemic myocardiopathy in four cases, severe mitral regurgitation in one case. This study confirms the relative frequency of cardiothyrotoxicosis, the proportionally weak place of Basedow disease among hyperthyroidy's causes, and role of associated cardiac disease to the hyperthyroid.

Treatment of hypothyroidism in elderly patients and in patients with cardiac disease

Hypothyroidism is often associated with adverse cardiovascular risk factors such as high cholesterol together with hypertension, endothelial dysfunction, and other atherosclerotic cardiovascular risk factors. The changed hemodynamic characteristics result in reduced cardiac index, and the renal perfusion is impaired with hyponatremia, and low renin and aldosterone production. The ischemic abnormalities are probably related to long-term consequences of a slow development of hypothyroidism, while the hemodynamic changes can develop in very short-term hypothyroidism. Replacement of hypothyroidism with levothyroxine is associated with a normalization of basal metabolic rate. Most patients with preexisting angina experience a gradual amelioration of symptoms, but in some cases the initial therapy may precipitate an unrecognized ischemic state, worsen a preexisting angina, or even result in myocardial infarction. It is therefore advisable to start replacement slowly and if needed perform a stress test and/or coronary angiography before. It may also in some cases be necessary to monitor the patients closely in a hospital setting during initiation of levothyroxine. Elderly hypothyroid patients with unstable angina pose a particular challenging problem, especially if coronary vascular surgery is indicated. No increased risk of peri- or postoperative death has been noted in small studies, although more complications have been described. It may be relevant to treat the cardiac vascular occlusion before starting replacement with levothyroxine in some cases, after careful weighting of pros and cons in each individual case.

Epidemiology, Mechanisms, and Risks

Atrial fibrillation (AF) is one of the most frequent complications of cardiac surgery, affecting more than one third of patients. The mechanism of this arrhythmia is believed to be reentry. The electrophysiologic substrate may be preexisting or may develop due to heterogeneity of refractoriness after surgery. Multiple perioperative factors have been proposed to contribute to the latter, including operative trauma, inflammation, elevations in atrial pressure (including that due to left ventricular diastolic dysfunction), autonomic nervous system imbalance, metabolic and electrolyte imbalances, or myocardial ischemic damage incurred during the operation. Whether ectopic beats originating in the pulmonary veins explain at least some episodes of postoperative AF, as has been shown for nonsurgical patients with the arrhythmia, is of current interest as such sites could easily be isolated at the time of surgery. The development of postoperative AF is associated with a higher risk of operative morbidity, prolonged hospitalization, and increased hospital cost compared with that in patients remaining in sinus rhythm. Many factors have been identified as being associated with postoperative AF, but the most consistent variable across studies is increasing patient age. It is speculated that age-related pathologic changes in the atrium contribute to arrhythmia susceptibility. An important modifiable risk factor for postoperative AF is the failure to resume therapy with beta-adrenergic receptor blockers after surgery. The stratification of patients who are at higher risk for AF would focus preventative strategies on patients who are most likely to benefit from such therapy. Nonetheless, since postoperative AF often develops in patients with comorbidities who are predisposed to other complications and prolonged hospitalization, it is presently unclear whether the prevention of postoperative AF will result in improved patient outcomes, particularly shorter hospitalizations.

Thyroid hormone action in the heart

The heart is a major target organ for thyroid hormone action, and marked changes occur in cardiac function in patients with hypo- or hyperthyroidism. T(3)-induced changes in cardiac function can result from direct or indirect T(3) effects. Direct effects result from T(3) action in the heart itself and are mediated by nuclear or extranuclear mechanisms. Extranuclear T(3) effects, which occur independent of nuclear T(3) receptor binding and increases in protein synthesis, influence primarily the transport of amino acids, sugars, and calcium across the cell membrane. Nuclear T(3) effects are mediated by the binding of T(3) to specific nuclear receptor proteins, which results in increased transcription of T(3)-responsive cardiac genes. The T(3) receptor is a member of the ligand-activated transcription factor family and is encoded by cellular erythroblastosis A (c-erb A) genes. T(3) also leads to an increase in the speed of diastolic relaxation, which is caused by the more efficient pumping of the calcium ATPase of the sarcoplasmic reticulum. This T(3) effect results from T(3)-induced increases in the level of the mRNA coding for the sarcoplasmic reticulum calcium ATPase protein, leading to an increased number of calcium ATPase pump units in the sarcoplasmic reticulum.

Thyroid Disorders in Elderly Patients

Thyroid disorders are common in the elderly and are associated with significant morbidity if left untreated. Typical symptoms may be absent and may be erroneously attributed to normal aging or coexisting disease. Physical examination of the thyroid gland may not be helpful, as the gland is often shrunken and difficult to palpate. Usually only myxedema coma requires levothyroxine parenterally; all other forms of hypothyroidism can be treated with oral levothyroxine. Low-dose levothyroxine should be initiated and increased gradually over several months. In unstable elderly patients with hyperthyroidism, antithyroid medication can quickly produce a euthyroid state. Radioactive iodine therapy is more definitive and is well tolerated, effective, and preferred. Surgical thyroid ablation may be necessary in patients who fail to respond to radioactive iodine therapy and in patients with multinodular goiter. If there is a suspicion of malignant disease, early biopsy or fine needle aspiration for cytology should be considered.

Hyperthyreoïdie bij ouderen: aspecifieke symptomen kunnen leiden tot uitstel van de diagnose

Thyreotoxicosis in the elderly: aspecific signs may cause a delay in diagnosis.The clinical manifestations of thyroid diseases in the elderly are often atypical and can easily be attributed to other medical conditions or 'normal aging'.Two nursing home patiënts with hyperthyroidism are described. Due to the atypical presentation of the thyroid disease their complaints were attributed to other conditions. In both patients there was a significant delay in diagnosis and treatment of hyperthyroidism.In elder patiens signs and symptoms of thyreotoxicosis are frequently related to cardiovascular, gastrointestinal and neuropsychiatric disorders. Most often occur atrial fibrillation, worsening of cardiac failure and angina pectoris, weight loss, anorexia, constipation, cognitive impairment and delirium.Delay of diagnosis and treatment of hyperthyroidism may be potentially harmful to the patient. Untreated thyreotoxicosis may lead to serious cardiovasculair complications (particularly cardiac failure and cerebrovascular accidents), mental deterioration and osteoporosis.In elder people with unexplained and vague signs and symptoms thyroid function should always be checked. The TSH assay is a very accurate diagnostic test for screening thyroid function. A normal TSH indicates euthyroidism with an accuracy of almost 100%.The medical treatment for hyperthyreoidism in the elderly are antithyroid drugs. When an euthyroid state is rendered, suppletion with L-thyroxine may be nessecary. Radioactive iodine treatment is preferred in some cases though there may be practical difficulties with the application of this treatment in nursing home patients because temporary isolation is necessary.

Acute ventricular rate control in atrial fibrillation and atrial flutter

Atrioventricular node blocking agents including beta-adrenergic blockers, non-dihydropyridine calcium channel blockers and digoxin are usually effective in controlling ventricular rate in atrial fibrillation and flutter. Intravenous beta-blockers and non-dihydropyridine calcium channel blockers are equally effective in rapidly controlling the ventricular rate. The addition of digoxin to the regimen causes a favorable outcome but digoxin as a single agent is generally less effective in slowing the ventricular rate in acute setting. Clonidine, magnesium, and amiodarone have also been used for acute ventricular rate control in atrial fibrillation. Limited data suggest that combination regimens provide better ventricular rate control than any agent alone. The agent of first choice is usually individualized depending upon the clinical situation. Beta-blockers are preferable in patients with myocardial ischemia, myocardial infarction and hyperthyroidism and in post-operative state, but should be avoided in patients with bronchial asthma and chronic obstructive pulmonary disease where non-dihydropyridine calcium channel blockers are preferred. Beta-blockers are preferred drugs used for acute ventricular rate control in atrial fibrillation during pregnancy. In atrial fibrillation with Wolff-Parkinson-White syndrome, beta-blockers, calcium channel blockers and digoxin should be avoided, as these drugs are selective atrioventricular node blockers without slowing conduction through the accessory pathway, which can lead to increased transmission of impulses preferentially through the accessory pathway and precipitate ventricular fibrillation. The drug of choice for atrial fibrillation in pre-excitation syndrome is procainamide but propafenone, flecainide and disopyramide have also been used. When clinical condition is unstable or patient is hemodynamically compromised, immediate electrical cardioversion is the treatment of choice, as the best measure to control ventricular rate is by conversion to sinus rhythm. Factors precipitating rapid ventricular rate should be treated as well.

Management of the Elderly Person After Myocardial Infarction

Elderly persons after myocardial infarction should have their modifiable coronary artery risk factors intensively treated. Hypertension should be treated with beta blockers and angiotensin-converting enzyme inhibitors. The blood pressure should be reduced to &lt;140/85 mmHg and to ≥130/80 mmHg in persons with diabetes or renal insufficiency. The serum low-density lipoprotein cholesterol should be reduced to &lt;100 mg/dl with statins if necessary. Aspirin or clopidogrel, beta blockers, and angiotensin-converting enzyme inhibitors should be given indefinitely unless contraindications exist to the use of these drugs. Long-acting nitrates are effective antianginal and antiischemic drugs. There are no Class I indications for the use of calcium channel blockers after myocardial infarction. Postinfarction patients should not receive Class I antiarrhythmic drugs, sotalol, or amiodarone. An automatic implantable cardioverter-defibrillator should be implanted in postinfarction patients at very high risk for sudden cardiac death. Hormonal therapy should not be used in postmenopausal women after myocardial infarction. The two indications for coronary revascularization are prolongation of life and relief of unacceptable symptoms despite optimal medical management.

L-thyroxine increases susceptibility of adult rats to low K+-induced ventricular fibrillation, and sinus rhythm restoration in old rats

Hypokalaemia increases the risk for life-threatening arrhythmias; however, data about interaction with thyroid status are lacking. The aim of this study was to investigate vulnerability of l-thyroxine (T(4))-treated adult and old rats to low K(+)-induced ventricular fibrillation (VF) as well as the ability of the heart to recover sinus rhythm. The experiments were performed on isolated heart preparations using the heart of 4- and 20-month-old female Wistar rats without and with feeding with T(4) 50 microg (100 g day)(-1) over a period of 2 weeks. Perfusion of the isolated heart with oxygenated Krebs-Henseleit solution at constant pressure was followed by perfusion with K(+)-deficient solution until occurrence of VF (< 10 min). After 2 min of sustained VF, the heart was perfused with normal solution for 10 min, during which sinus rhythm was restored. ECG, left ventricular pressure (LVP) and coronary flow were continuously monitored. The results showed that compared with untreated rats, the onset of low K(+)-induced ventricular premature beats was delayed and their number was significantly decreased in both T(4)-treated groups. Nevertheless, VF occurred earlier in T(4)-treated than in non-treated adult rats (6.78 +/- 0.28 vs. 9.59 +/- 0.55 min, P < 0.05), whereas the difference was not significant in aged animals. Furthermore, sinus rhythm appeared earlier in old T(4)-treated rats compared with non-treated rats (7.18 +/- 0.57 vs. 8.94 +/- 0.64 min, P < 0.05), whereas in adult hearts it set in at practically the same time regardless of treatment. In conclusion, our results indicate that administration of a pharmacological dose of T(4) can increase the risk of low K(+)-induced VF in adult but not in old animals; in the latter it even facilitated restoration of sinus rhythm. Moreover, enhanced mechanical function was observed in both adult and old T(4)-treated hearts.

Evaluation of endothelial function in subclinical hypothyroidism and subclinical hyperthyroidism

Subclinical hypothyroidism and subclinical hyperthyroidism are two frequently occurring conditions for which exact therapeutic approaches have not yet been established. The aim of this study was to compare the endothelial function and carotid artery intimae-media thickness (IMT) of these two groups of patients to euthyroid subjects and to assess the effects of these conditions on endothelial function. Study groups comprised of 25 subclinical hypothyroid patients (mean age, 32.28 +/- 9.67 years), 13 subclinical hyperthyroid patients (mean age, 35.69 +/- 9.67 years), and 23 euthyroid subjects (mean age, 35.87 +/- 7.93 years). They were evaluated for flow-mediated dilatation (FMD), and carotid artery IMT. The groups were matched strictly for atherosclerotic risk factors. The subclinical hypothyroid group was found to have significantly lower FMD values. No significant differences were observed between the groups with respect to other vascular parameters. The only discriminative factor between the groups was the state of their thyroid function. Therefore, subclinical hypothyroidism may have adverse effects on endothelial function independent from other well-known atherosclerotic risk factors.

Pharmacologic management of atrial fibrillation in the elderly: rate control, rhythm control, and anticoagulation

Atrial fibrillation (AF) is the most prevalent major arrhythmia in the elderly. It may lead to significant morbidity and mortality through both primary cardiac effects and thromboembolic complications. It is controversial how aggressive physicians should be in their efforts to maintain normal sinus rhythm. Clearly, elderly patients with hemodynamic impairment or other symptoms of AF should undergo attempts to convert AF and maintain normal sinus rhythm, by means of cardioversion and initiation of antiarrhythmic medications. In patients left in AF, rate control with atrioventricular nodal-slowing agents is appropriate. The use of anticoagulation in the elderly is often complicated by concerns about excessive bleeding or falls in this population; however, evidence strongly supports the need for anticoagulation with close monitoring even in the extreme elderly. Because of the high prevalence of asymptomatic AF and the high burden of thromboembolism in the elderly, even patients ostensibly maintained in normal sinus rhythm should continue systemic anticoagulation in the absence of contraindications.

Hypothyroidism in patients older than 55 years: an analysis of the etiology and assessment of the effectiveness of therapy

BACKGROUND

Several epidemiological studies on the prevalence of hypothyroidism in the elderly have been reported; however, extensive series of elderly patients with thyroid dysfunction have not been studied. Our aim has been to assess the relative frequency of the diverse causes of hypothyroidism in a group of patients older than 55 years and the adequacy of control of thyroid function attained by levothyroxine therapy.

METHODS

We performed a descriptive, observational, cross-sectional study in the setting of a hospital endocrinology clinic. From a total of 1581 patients older than 55 who were complaining of a thyroid disorder, we studied a group of 655 patients with hypothyroidism. There were 559 women (85.3%, age 65.01 +/- 7.90 years) and 96 men (14.7%, 65.36 +/- 8.39 years). In every patient, we collected etiology, presence of goiter, time of evolution from diagnosis and from therapy prescription, previous and present treatments, current thyroid functional status (free thyroxine and thyrotropin concentration), adequacy of disease control, and thyroid autoimmune status.

RESULTS

The causes of hypothyroidism were as follows: autoimmune thyroiditis, 308 (47.0%); postoperative hypothyroidism, 175 (26.7%); therapy for previous thyrotoxicosis, 63 (9.6%); thyrotropin deficiency, 15 (2.3%); iodine excess, 6 (0.9%); subacute thyroiditis, 2 (0.3%); and unknown etiology, 86 (13.1%) patients. Most patients with autoimmune thyroiditis were positive for thyroid peroxidase antibodies at the time of the study (94.4%). Mean (+/- SD) age at diagnosis was 61.8 +/- 9.4 years in men and 59.8 +/- 9.7 years in women. Median (range) duration of hypothyroidism was 1.4 (0-18) years in men and 3 (0-45) years in women ( p <.05). Adequacy of therapy was studied in 385 patients treated with replacement doses of levothyroxine. Two hundred and sixty (67.5%) of these subjects attained good control, whereas 125 (32.5%) showed inadequate control of the disease at the time of the study. A model of logistic regression showed that adequacy of therapy was dependent on the duration of therapy, but independent of age, gender, degree of hypothyroidism, etiology, autoimmune status, age at diagnosis, and dose of levothyroxine. A 2-year follow-up study performed in 56 newly diagnosed patients showed that an adequate control of hypothyroidism was attained in 35 (62.5%) patients at 6 months, in 46 (82.1%) patients at 1 year, and in 49 (87.5%) at 2 years of therapy with levothyroxine.

CONCLUSIONS

Autoimmune thyroiditis and postoperative hypothyroidism are the main causes of thyroid hypofunction in patients older than 55 years. The time from starting therapy is the main determinant of the adequacy of control of thyroid hypofunction in this population. With effective therapy and appropriate monitoring, more than 80% of the patients showed adequate control within 1 year of follow-up.

Endothelial function in patients with hyperthyroidism before and after treatment with propranolol and thiamazol

Hyperthyroidism is associated with a higher incidence of arterial thromboembolism; increasing age, atrial fibrillation, and mitral valve abnormalities are risk factors. However, the contribution of endogenous coagulation parameters is unclear. Because thyroid hormone influences receptor and transcription factors, it can be expected that it will influence proteins involved in coagulation processes synthetised in many cells. Fourteen hyperthyroid patients were studied untreated, after 1 week of treatment with propranolol, and after therapeutic treatment with thiamazol. Fourteen matched controls were used for comparison. On each occasion, endothelial marker proteins, coagulation/fibrinolysis factors, and inflammatory (liver) markers were measured. Excess thyroid hormone was associated with elevated levels of most endothelium-associated proteins. In addition, plasma fibronectin and fibrinogen were increased, while plasminogen was decreased. No evidence was found that hyperthyroidism was associated with coagulation/fibrinolysis activation, or with increased levels of the inflammation markers interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) or C-reactive protein (CRP). Propranolol treatment only lowered the von Willebrand factor propeptide, and slightly increased plasminogen. Treatment with thiamazol returned all parameters to normal. Hyperthyroidism increased the plasma levels of most endothelial marker proteins, and of some liver-synthetized proteins. No evidence for coagulation/fibrinolysis activation was found. However, it appears that endothelial activation, which is indicative of a procoagulant state, is present in hyperthyroidism. This may explain the association between hyperthyroidism and thromboembolism especially if other risk factors are present. von Willebrand factor II (vWF:Ag-II) levels may be suitable markers to evaluate acute changes in endothelial function because this parameter responds more rapidly to changes in endothelial function than other factors.

Treatment of Hypertension in the Institutionalized Elderly

The goal of antihypertensive therapy in elderly institutionalized persons is to reduce the blood pressure to less than 140/90 mm Hg if possible. Elderly persons with diastolic hypertension should have their diastolic blood pressure lowered to 80-85 mm Hg. Elderly persons with stage 2 or 3 hypertension, stage 1 hypertension and target organ damage, evidence of clinical cardiovascular disease, or diabetes mellitus should be treated with antihypertensive drug therapy immediately in addition to lifestyle modification. The initial antihypertensive drug in elderly persons without associated medical conditions should be a diuretic or à -blocker because these drugs have been shown to decrease cardiovascular morbidity and mortality in controlled clinical trials. The initial antihypertensive drug in elderly persons should depend on the associated medical condition. If a second antihypertensive drug is indicated, a drug from another class should be administered. If a diuretic is not the initial drug, it is usually indicated as the second drug. If the antihypertensive response is inadequate after reaching the full dose of two classes of drugs, a third drug from another class should be added. Causes of secondary hypertension should be identified and treated. (c)2000 by CVRR, Inc.

Cardiac risks of hyperthyroidism in the elderly

The importance of cardiovascular system involvement in hyperthyroidism has been recognized for many years. In the elderly patient, often with mild but prolonged elevation of plasma thyroid hormones, symptoms and signs of heart failure and complicating atrial fibrillation (AF) may dominate the clinical picture and mask the more classic endocrine manifestations of the disease. Impaired cardiopulmonary function and exercise capacity, significantly more marked in older patients, is observed in hyperthyroidism. Thyrotoxicosis can aggravate pre-existing heart disease and can also lead to AF, congestive heart failure, or worsening of angina pectoris. Regarding the high incidence of AF in older patients with hyperthyroidism, it is also important to detect subclinical hyperthyroidism in older patients with AF, thus warranting the measurement of the serum thyrotropin (TSH) concentration for early recognition and treatment. Most cardiac abnormalities return to normal once a euthyroid state has been achieved, although AF may persist in a minority. Optimal treatment requires rapid and definitive antithyroid therapy. Furthermore, anticoagulation is recommended for thyrotoxic patients with AF older than 50 years, those who have histories of previous emboli, hypertension, or with echocardiographic evidence of left atrial enlargement and/or myxomatous valves.