Myocardial scintigraphic characteristics in patients with primary aldosteronism

Predicting the clinical course in hypertrophic cardiomyopathy using thallium-201 myocardial scintigraphy

Aims

This study aimed to evaluate the changes in left ventricular remodelling with time in patients with hypertrophic cardiomyopathy (HCM) using thallium‐201 myocardial scintigraphy.

Methods and results

Forty‐eight patients with HCM participated in the study. The extent score (ES) and a newly devised index termed the ‘mean count change’ (MCC) were used to evaluate the myocardial perfusion defects. Using the amount of thallium‐201 uptake (TU), MCC (%) was calculated using the following formula: (last TU − initial TU)∕initial TU × 100. To confirm the site of the lesion, the left ventricle was divided into five segments: anterior, septal, inferior, lateral, and apex. Cardiovascular complications and deaths were recorded. The mean follow‐up period was 8.6 ± 2.0 years. ES increased from 17.4 ± 13.7% to 44.0 ± 22.3% (P < 0.0001). MCC increased from 0% to 12.0 ± 9.0% (P < 0.0001). The apex was the most frequent site of lesion. Twenty‐seven patients (56.3%) had experienced left ventricular heart failure (LVHF). Both ES and MCC were greater in patients with LVHF than in those without LVHF. An overlap between the two groups was greater in ES than in MCC. Patients with LVHF had a higher incidence of atrial fibrillation and apoplexy. Nineteen patients (39.6%) died during the study period; 14 died from LVHF, 3 from sudden cardiac death, and 2 from cancer.

Conclusions

Thallium‐201 myocardial scintigraphy is useful for detecting the severity of myocardial damage and for confirming the lesion site in patients with HCM. MCC may be superior to ES in the evaluation of these changes with time.

Aldosterone and parathyroid hormone interactions as mediators of metabolic and cardiovascular disease

Inappropriate aldosterone and parathyroid hormone (PTH) secretion is strongly linked with development and progression of cardiovascular (CV) disease. Accumulating evidence suggests a bidirectional interplay between parathyroid hormone and aldosterone. This interaction may lead to a disproportionally increased risk of CV damage, metabolic and bone diseases. This review focuses on mechanisms underlying the mutual interplay between aldosterone and PTH as well as their potential impact on CV, metabolic and bone health. PTH stimulates aldosterone secretion by increasing the calcium concentration in the cells of the adrenal zona glomerulosa as a result of binding to the PTH/PTH-rP receptor and indirectly by potentiating angiotensin 2 induced effects. This may explain why after parathyroidectomy lower aldosterone levels are seen in parallel with improved cardiovascular outcomes. Aldosterone mediated effects are inappropriately pronounced in conditions such as chronic heart failure, excess dietary salt intake (relative aldosterone excess) and primary aldosteronism. PTH is increased as a result of (1) the MR (mineralocorticoid receptor) mediated calciuretic and magnesiuretic effects with a trend of hypocalcemia and hypomagnesemia; the resulting secondary hyperparathyroidism causes myocardial fibrosis and disturbed bone metabolism; and (2) direct effects of aldosterone on parathyroid cells via binding to the MR. This adverse sequence is interrupted by mineralocorticoid receptor blockade and adrenalectomy. Hyperaldosteronism due to klotho deficiency results in vascular calcification, which can be mitigated by spironolactone treatment. In view of the documented reciprocal interaction between aldosterone and PTH as well as the potentially ensuing target organ damage, studies are needed to evaluate diagnostic and therapeutic strategies to address this increasingly recognized pathophysiological phenomenon.

Outcome of surgery for primary hyperaldosteronism

BACKGROUND

Primary hyperaldosteronism (PHA) frequently causes secondary hypertension and is a surgically amenable disease if associated with unilateral adenoma. Patients who underwent laparoscopic adrenalectomy at the authors' department were followed to identify clinical parameters that predict resolution of hypertension.

METHODS

All patients with PHA and adrenalectomy from 1993 to 2009 were identified. Charts and follow-up data were reviewed for clinical parameters and hormone levels. Univariate and multivariate analysis were performed with SPSS 15.0.

RESULTS

A cohort of 30 female and 24 male patients underwent laparoscopic adrenalectomy. Hypokalemia was observed in 47/54 (87%) patients. Twenty patients (37%) were cured without any further need of antihypertensive medication, 20 (37%) patients experienced an improvement in hypertension, and 14 (26%) patients remain unaffected. Consequently, hypertension was resolved or improved in 40/54 (74%) patients. A shorter duration of hypertension (<6 years), the number of antihypertensive drugs (<3), and the serum creatinine level (<1.3 mmol/l) were independent predictors of resolution of hypertension in a multivariate analysis. At final follow-up after a mean of 49 ± 40 months, resolution of hypertension was observed in 17/30 (57%) patients. Interestingly, in 10/17 patients a period longer than 12 months was required before a resolution of hypertension was observed. Coexistent hyperplasia, which was observed in 30% of patients, did not correlate with outcome.

CONCLUSIONS

In 50% of patients with PHA, hypertension resolves after laparoscopic adrenalectomy, but the process may require more than 12 months. Patients with a duration of hypertension of more than 6 years, more than 3 antihypertensive drugs, and elevated serum creatinine have a higher risk of persistent hypertension after surgery. Coexistent hyperplasia in the resected adrenal gland is not associated with persistent hypertension.

Iodine-123 metaiodobenzylguanidine cardiac imaging as a method to detect early sympathetic neuronal dysfunction in chagasic patients with normal or borderline electrocardiogram and preserved ventricular function

PURPOSE

The indeterminate form of Chagas disease represents the most common chronic presentation. The aim of this study was to assess cardiovascular autonomic system function with I-123 metaiodobenzylguanidine (MIBG) scintigraphy in chagasic patients with normal or "borderline" electrocardiographic alterations and preserved left ventricular function evaluated by echocardiography.

MATERIALS AND METHODS

A total of 40 chagasic patients and 19 control subjects were included in this study. Patients had normal echocardiogram and chest radiography; no arrhythmias or myocardial ischemia; and normal exercise performance for age, gender, and body mass index. I-123 MIBG scintigraphy was performed and the heart-to-mediastinum (H/M) uptake was used as the primary predictor in the present analysis. The data analysis was performed by using Nonparametric Regression Trees and the Survival Agreement Plot. We included only patients with preserved right and left ventricular function assessed by echocardiographic methods.

RESULTS

Variables analyzed in the regression tree were age, sex, 20 minutes and 3 hours H/M uptake after injection of I-123 MIBG, washout rate, and single photon emission computed tomography imaging. The 3 hours H/M ratio was the only significant variable (P<0.001) and for 95% of chagasic patients, this value was less than 2.19.

CONCLUSIONS

This study presents evidence that cardiac autonomic sympathetic modulation may be affected in chagasic subjects with preserved ventricular function evaluated by echocardiography, especially in those with "borderline" electrocardiogram.

Effect of Beta-Blocker Therapy on Myocardial Perfusion Defects in Thallium-201 Scintigraphy in Patients with Dilated Cardiomyopathy

BACKGROUND

The beneficial effects of beta-blocker therapy in patients with heart failure have been confirmed. However, the effects of beta-blockers on myocardial perfusion defects are unclear. The aim of this study was to evaluate the effect of beta-blockers on myocardial perfusion defects estimated by thallium-201 myocardial scintigraphy in patients with dilated cardiomyopathy (DCM) and to investigate the relationships between beta-blocker treatment and myocardial damage and cardiac function.

METHODS

201Tl and echocardiography were performed in 37 patients before and after 6 months of beta-blocker therapy. Extent score (ES) by 201Tl was used to quantitate myocardial perfusion defects before and after treatment.

RESULTS

ES was significantly decreased by beta-blocker therapy. According to the change in ES, DCM patients were classified into three groups, patients who improved, patients showing no change and patients who deteriorated. In the improvement and no-change groups, beta-blocker therapy induced a reduction in left ventricular dimensions and an associated increase in ejection fraction. However, in the deterioration group, left ventricular dimensions and ejection fraction were unchanged. There was a significant relationship between the change in left ventricular dimension at end-diastole and the change in ES.

CONCLUSIONS

beta-Blocker therapy could attenuate myocardial perfusion defects in some patients with DCM. The improvement in left ventricular function associated with beta-blocker therapy may be related to the attenuation in myocardial perfusion defects.

Circulating levels of heart-type fatty acid-binding protein and its relation to thallium-201 perfusion defects in patients with hypertrophic cardiomyopathy

Myocyte loss and replacement fibrosis have been observed in patients with hypertrophic cardiomyopathy (HC) with heart failure. This study was designed to elucidate whether heart-type fatty acid-binding protein (H-FABP), a sensitive biochemical marker for myocardial damage, indicates ongoing myocardial damage in patients with HC. We studied 48 patients with HC and 17 control subjects. Patients with HC were divided into 2 groups according to the New York Heart Association (NYHA) functional class: NYHA I + II (n = 40) and NYHA III + IV (n = 8). Serum H-FABP and myoglobin levels were measured, and extent score was used to assess the extent of thallium-201 perfusion defect. Serum H-FABP levels were significantly higher in patients with HC than in control subjects (3.8 +/- 1.6 vs 2.6 +/- 0.7 ng/ml, p = 0.0032). Furthermore, serum H-FABP levels were significantly higher in NYHA III + IV than in NYHA I + II (5.2 +/- 1.3 vs 3.5 +/- 1.5 ng/ml, p = 0.0043). Serum myoglobin levels showed no significant difference among the 3 groups (control, 46.6 +/- 15.0 ng/ml; NYHA I + II, 55.5 +/- 26.4 ng/ml; NYHA III + IV, 65.1 +/- 33.6 ng/ml, p = 0.2115). Extent score correlated positively with serum H-FABP levels (r = 0.420, p = 0.0026) and negatively with fractional shortening (r = -0.542, p <0.0001). Increased H-FABP levels indicate ongoing myocardial damage, which could result in clinical deterioration in patients with HC.

New Approaches to the Minimally Invasive Treatment of Adrenal Lesions

The advancement of laparoscopic adrenalectomy over the past decade has completely changed the surgical approach to adrenal tumors. As the incidence of incidentally discovered adrenal tumors increases, most patients with resectable lesions can undergo resection laparoscopically with minimal morbidity, shorter hospitalization, and low mortality. The spectrum of surgical approaches now available make it possible to provide an appropriate resection that is matched to the specific characteristics of each tumor. Experienced surgeons now resect some malignant tumors laparoscopically, with the option to convert to a hand-assisted or traditional open approach.

Myocardial microvascular abnormalities observed by intravenous myocardial contrast echocardiography in patients with hypertrophic cardiomyopathy

We tested the hypothesis that myocardial microvascular abnormalities occur and are influenced by clinical features in 30 patients with hypertrophic cardiomyopathy (HC) using intravenous myocardial contrast echocardiography. Patients with HC were subdivided into 3 groups: nonobstructive HC (n = 12), obstructive HC (n = 10), or HC with systolic dysfunction and heart failure (n = 8). In patients with nonobstructive HC and obstructive HC, subendocardial peak myocardial contrast intensity at the mid-septal area was significantly decreased and the transmyocardial difference of peak myocardial contrast intensity between subendocardial and periendocardial regions at the mid-septal area was significantly related to regional wall thickness. Reduced peak myocardial contrast intensities at the mid-septal subendocardial and periendocardial regions were observed in patients with HC and heart failure. Our study indicates that subendocardial microvascular abnormalities during end-systole may be associated with severity of regional myocardial hypertrophy in patients with nonobstructive HC and obstructive HC. In addition, progressive microvascular damage may occur in patients with HC and heart failure.

Relation of Myocardial Blood Volume to Left Ventricular Function and Future Cardiac Events in Patients With Idiopathic Dilated Cardiomyopathy

BACKGROUND

The hypothesis that myocardial blood volume is associated with left ventricular (LV) dysfunction and future cardiovascular events in patients with idiopathic dilated cardiomyopathy (IDC) was tested using intravenous myocardial contrast echocardiography (MCE).

METHODS AND RESULTS

Thirty-five patients with IDC and 10 age-matched healthy control subjects were enrolled. Using MCE, background-subtracted and peak myocardial contrast intensity (calibrated PMCI) were calculated as measures of myocardial blood volume. LV ejection fraction (LVEF) was calculated using the modified Simpson method. Patients with IDC were stratified into 2 groups according to the median value of the calibrated PMCI [high value group (n=17): calibrated PMCI > or = -22.7 dB, low value group (n=18): calibrated PMCI < -22.7 dB]. The calibrated PMCI was markedly reduced in patients with IDC compared with the control subjects (p=0.0025) and closely related to LVEF (r=0.688, p<0.0001). In the multivariate model, calibrated PMCI was the independent variable that predicted cardiac events in patients with IDC. According to the Kaplan-Meier analysis, cardiac event-free rates were significantly lower in the low-value group than in the high-value group (p<0.01).

CONCLUSIONS

Myocardial blood volume is closely related to LV dysfunction and future cardiac events in patients with IDC.

Primary aldosteronism

Approaching the fiftieth year since its original description, primary aldosteronism is now thought to be the commonest potentially curable and specifically treatable form of hypertension. Correct identification of patients with primary aldosteronism requires that the effects of time of day, posture, dietary sodium intake, potassium levels and medications on levels of aldosterone and renin be carefully considered. Accurate elucidation of the subtype is essential for optimal treatment, and adrenal venous sampling is the only reliable means of differentiating aldosterone-producing adenoma from bilateral adrenal hyperplasia. With genetic testing already available for one inherited form, making more cumbersome biochemical testing for that subtype virtually obsolete and bringing about improvements in treatment approach, an intense search is underway for genetic mutations causing other, more common familial varieties of primary aldosteronism.

Primary aldosteronism - treatment options

Diagnosis of primary aldosteronism results in either the surgical cure of hypertension or targeted pharmacotherapy. The two major subtypes of primary aldosteronism are unilateral aldosterone-producing adenoma (APA) and bilateral idiopathic hyperaldosteronism (IHA). Patients with APA usually are treated with unilateral adrenalectomy and patients with IHA are treated medically. The majority of patients with primary aldosteronism have the IHA subtype and require pharmacotherapy. Spironolactone has been the drug of choice to treat primary aldosteronism. However, it is not selective for the aldosterone receptor, and side effects include gynecomastia, erectile dysfunction and menstrual irregularity. Eplerenone is a new competitive and selective aldosterone receptor antagonist recently approved by the United States Food and Drug Administration for the treatment of hypertension. It lacks the side effects associated with spironolactone and will be the superior drug if it is shown to be as effective as spironolactone for the treatment of mineralocorticoid-dependent hypertension.

Minireview: primary aldosteronism--changing concepts in diagnosis and treatment

Primary aldosteronism affects 5-13% of patients with hypertension. Patients with hypertension and hypokalemia and most patients with treatment-resistant hypertension should undergo screening for primary aldosteronism with a plasma aldosterone concentration to plasma renin activity ratio. A high plasma aldosterone concentration to plasma renin activity ratio is a positive screening test result, a finding that warrants confirmatory testing. For those patients that want to pursue a surgical cure, the accurate distinction between the subtypes (unilateral vs. bilateral adrenal disease) of primary aldosteronism is a critical step. The subtype evaluation may require one or more tests, the first of which is imaging the adrenal glands with computed tomography, followed by selective use of adrenal venous sampling. Because of the deleterious cardiovascular effects of aldosterone, normalization of circulating aldosterone or aldosterone receptor blockade should be part of the management plan for all patients with primary aldosteronism. Unilateral laparoscopic adrenalectomy is an excellent treatment option for patients with unilateral aldosterone-producing adenoma. Bilateral idiopathic hyperaldosteronism should be treated medically. In addition, aldosterone-producing adenoma patients may be treated medically if the medical treatment includes mineralocorticoid receptor blockade.

New perspectives on the role of aldosterone excess in cardiovascular disease

1. Evidence from recent experimental and clinical studies suggests that excessive circulating levels of aldosterone can bring about adverse cardiovascular sequelae independent of the effects on blood pressure. Examples of these sequelae are the development of myocardial and vascular fibrosis in uninephrectomized, salt-loaded rats infused with mineralocorticoids and, in humans, an association of aldosterone with left ventricular hypertrophy, impaired diastolic and systolic function, salt and water retention causing aggravation of congestion in patients with established congestive cardiac failure (CCF), reduced vascular compliance and an increased risk of arrhythmias (resulting from intracardiac fibrosis, hypokalaemia, hypomagnesaemia, reduced baroreceptor sensitivity and potentiation of catecholamine effects). 2. These sequelae of aldosterone excess may contribute to the pathogenesis and worsen the prognosis of CCF and hypertension. 3. The heart and blood vessels may be capable of extra-adrenal aldosterone biosynthesis, raising the possibility that aldosterone may have paracrine or autocrine (and not just endocrine) effects on cardiovascular tissues. 4. The high prevalence of CCF, which is associated with secondary aldosteronism, and primary aldosteronism (PAL; recently recognized to be a much more common cause of hypertension than was previously thought) argue for an important role for aldosterone excess as a cause of cardiovascular injury. 5. The recognition of non-blood pressure-dependent adverse sequelae of aldosterone excess raises the question as to whether normotensive individuals with PAL, who have been detected as a result of genetic or biochemical screening among families with inherited forms of PAL, are at excess risk of cardiovascular events. 6. Provided that patients are carefully investigated in order to permit the appropriate selection of specific surgical (laparoscopic adrenalectomy for PAL that lateralizes on adrenal venous sampling) or medical (treatment with aldosterone antagonist medications) management and safety considerations for the use of aldosterone antagonists are kept in mind, the appreciation of a widening role for aldosterone in cardiovascular disease should provide a substantially better outlook for many patients with CCF and hypertension.