Left ventricular systolic/diastolic function evaluated by quantitative ECG-gated SPECT: comparison with echocardiography and plasma BNP analysis

Frequent cyclic variation of heart rate is associated with left ventricular diastolic dysfunction in patients without ischemia

BACKGROUND

Cyclic variation of heart rate (CVHR) associated with sleep-disordered breathing reflects cardiac autonomic responses to apneic/hypoxic stress. However, the association of CVHR with cardiac function is unclear.

METHODS

We investigated a total of 181 patients who underwent both 24-hour Holter electrocardiography (ECG) and quantitative gated single-photon emission computed tomography (SPECT) myocardial functional imaging, excluding patients with atrial fibrillation, myocardial infarction, structural heart disease, and implantable devices, from January 2017 to July 2018. The number of CVHR per hour (CVHR index) in sleeping-time Holter ECG was compared with the parameters of left ventricular (LV) systolic and diastolic functions assessed by cardiac SPECT functional imaging, peak filling rate (PFR), first-third mean filling rate (1/3 MFR), and time to peak filling rate (TTPF).

RESULTS

In all patients, the CVHR index was not associated with any parameters of cardiac functions. However, in a propensity score-matched subgroup of patients without ischemia (N = 39), the CVHR index was negatively correlated with PFR (r = -0.35, P < .05) and 1/3 MFR (r = -0.37, P < .05) but positively correlated with TTPF (r = 0.43, P < .01) and was not correlated with LV ejection fraction. Multivariate linear regression analysis revealed that high CVHR index was independently associated with LV diastolic dysfunction, even after adjusting for the relative wall thickness and LV mass index assessed by echocardiography.

CONCLUSION

These results indicate that the high frequency of CVHR in sleeping time is associated with LV diastolic dysfunction in nonischemic patients, irrespective of LV geometry.

Assessment of LV diastolic dysfunction in myocardial perfusion imaging: a correlative study with transthoracic echocardiography

OBJECTIVE

Myocardial perfusion imaging (MPI) by gated single-photon emission computed tomography (SPECT) is a feasible method in the evaluation of left ventricular perfusion and function. The purpose of this study was to determine the threshold and grading of left ventricular (LV) diastolic dysfunction (LVDD) using gated SPECT MPI.

METHODS

A total of 149 patients were recruited in the study. All of the patients underwent a standard 2-day stress/rest gated MPI study and transthoracic echocardiography within 2 weeks. The reconstructed rest-only images were analyzed by Cedar-Sinai's quantitative gated SPECT and the LV diastolic parameters, including peak filling rate (PFR), time to PFR (TTPF) and secondary PFR (PFR2) to PFR ratio were provided and compared to echocardiographic data.

RESULTS

68 (45.6%) and 81 (54.4%) of patients were categorized in LVDD-absent and LVDD-present groups on the basis of LVDD evidence in echocardiography, respectively. receiver-operating-characteristic analysis for PFR and TTPF was performed, resulting in diagnostic sensitivities of 70 and 57% and specificities of 60 and 75% for PFR <2.6 end-diastolic volumes (EDV)/s and TTPF>160.5 ms, respectively. Applying our previously used thresholds of <1.70 EDV/s for PFR, >208 ms for TTPF and >1 for PFR2/PFR, sensitivities and specificities of 9.9 and 96.6%, 9.9 and 95.6% and 13.8 and 88% were resulted, respectively. Grading of LVDD on the basis of MPI-obtained diastolic parameters showed considerable overlapping data by interquartile range.

CONCLUSION

Gated SPECT MPI can be used as a highly specific means for detection of LV diastolic dysfunction when compared to echocardiography. However, grading of severity of diastolic heart failure appears to be impracticable.

Combination of Linagliptin and Empagliflozin Preserves Cardiac Systolic Function in an Ischemia-Reperfusion Injury Mice With Diabetes Mellitus

Background

Sodium-glucose co-transporter 2 inhibitor (SGLT2i) and dipeptidyl peptidase 4 inhibitor (DPP4i) are oral hypoglycemic agents. Although SGLT2i has been shown having the beneficial effects on heart failure in basic and clinical studies, the combined effects of SGLT2i and DPP4i have not been established well. We investigated the effects of SGLT2i and DPP4i against diabetes mice model of myocardial ischemia-reperfusion injury.

Methods

Streptozotocin-induced diabetic C57BL/6J mice were divided into control (vehicle), empagliflozin (30 mg/kg/day), linagliptin (3 mg/kg/day) and combination (30 mg/kg/day and 3 mg/kg/day, respectively) groups. After 7 days of drug administration, 30 min of myocardial ischemia was performed. We investigated body weight, heart weight, blood glucose, and cardiac functions by pressure-volume Millar catheter followed by 28 days of additional drug administration.

Results

Blood glucose levels, body weight, and heart weight were not significantly different between the groups. In Millar catheter analysis, left ventricular volume at the peak left ventricular ejection rate which is one of the cardiac systolic parameters in combination group was significantly preserved than that in control (P = 0.036). The cardiac index in the combination group tended to be preserved compared to that in the control (P = 0.06). The pathological fibrotic area in the left ventricle in the combination group also tended to be smaller (P = 0.08).

Conclusions

Combination therapy with linagliptin and empagliflozin preserved cardiac systolic function on the diabetes mice model of myocardial ischemia-reperfusion injury independent of blood glucose levels.

Impact of basal inferolateral scar burden determined by automatic analysis of 99mTc-MIBI myocardial perfusion SPECT on the long-term prognosis of cardiac resynchronization therapy

AIMS

Left-ventricular (LV) scarring may be associated with a poor response to cardiac resynchronization therapy (CRT). The automatic analysis of myocardial perfusion single-photon emission computed tomography (MP-SPECT) may provide objective quantification of LV scarring. We investigated the impact of LV scarring determined by an automatic analysis of MP-SPECT on short-term LV volume response as well as long-term outcome.

METHODS AND RESULTS

We studied consecutive 51 patients who were eligible to undergo 99mTc-MIBI MP-SPECT both at baseline and 6 months after CRT (ischaemic cardiomyopathies 31%). Quantitative perfusion SPECT was used to evaluate the defect extent (an index of global scarring) and the LV 17-segment regional uptake ratio (an inverse index of regional scar burden). The primary outcome was the composite of overall mortality or first hospitalization for worsening heart failure. A high global scar burden and a low mid/basal inferolateral regional uptake ratio were associated with volume non-responders to CRT at 6 months. The basal inferolateral regional uptake ratio remained as a predictor of volume non-response after adjusting for the type of cardiomyopathy. During a median follow-up of 36.1 months, the outcome occurred in 28 patients. The patients with a low basal inferolateral regional uptake ratio with a cutoff value of 57% showed poor prognosis (log-rank P= 0.006).

CONCLUSION

The scarring determined by automatic analysis of MP-SPECT images may predict a poor response to CRT regardless of the pathogenesis of cardiomyopathy. The basal inferolateral scar burden in particular may have an adverse impact on long-term prognosis.

Non-invasive measurement of volume-time curves in patients with mitral regurgitation and in healthy volunteers, using a new operator-independent screening tool

Left ventricular volume-time curves (VTCs) provide hemodynamic data, and may help clinical decision making. The generation of VTCs using echocardiography, however, is time-consuming and prone to inter-operator variability. In this study, we used a new non-invasive, operator-independent technique, the hemodynamic cardiac profiler (HCP), to generate VTCs. The HCP, which uses a low-intensity, patient-safe, high-frequency applied AC current, and 12 standard ECG electrodes attached on the thorax in a pre-defined pattern, was applied to five young healthy volunteers, five older healthy volunteers, and five patients with severe mitral regurgitation. From the VTCs generated by the HCP, the presence or absence of an isovolumetric contraction phase (ICP) was assessed, as well as the left ventricular ejection time (LVET), time of the pre-ejection period (tPEP), and ratio of the volumes of the early (E) and late (A) diastolic filling (E _V/A _V ratio), and compared to 2D transthoracic echocardiography (2D TTE) at rest. The reproducibility by two different operators showed good results (RMS  =  5.2%). For intra-patient measurement RMS was 2.8%. Both LVET and the E _V/A _V ratio showed a strong significant correlation between HCP and 2D TTE derived parameters (p  <  0.05). For tPEP, the correlation was still weak (p  =  0.32). In all five patients with mitral regurgitation, the ICP was absent in the VTC from the HCP, whereas it was present in the 10 healthy volunteers, which is in accordance with pathophysiology. We conclude that the HCP seems to be a method for reproducible VTC generation, and may become a useful early screening tool for cardiac dysfunction in the future.

The prognostic value of non-perfusion variables obtained during vasodilator stress myocardial perfusion imaging

Myocardial perfusion imaging (MPI) is an established diagnostic test that provides useful prognostic data in patients with known or suspected coronary artery disease. In more than half of the patients referred for stress testing, vasodilator stress is used in lieu of exercise. Unlike exercise, vasodilator stress does not provide information on exercise and functional capacity, heart rate recovery, and chronotropy, and ECG changes are less frequent. These non-perfusion data provide important prognostic and patient management information. Further, event rates in patients undergoing vasodilator MPI are higher than in those undergoing exercise MPI and even in those with normal images probably due to higher pretest risk. However, there are a number of non-perfusion variables that are obtained during vasodilator stress testing, which have prognostic relevance but their use has not been well emphasized. The purpose of this review is to summarize the prognostic values of these non-perfusion data obtained during vasodilator MPI.

Cardiac function changes with switching from the supine to prone position: analysis by quantitative semiconductor gated single-photon emission computed tomography

BACKGROUND

Prone positioning is required in certain operations such as spinal surgery. Changes in cardiac function in the prone position have been studied with various methodologies. Few studies have investigated changes in left ventricular diastolic function and rhythm in subjects turned prone.

METHODS AND RESULTS

Cardiac function was evaluated in the supine and prone positions in 90 patients without atrial fibrillation who underwent (99m)Tc-tetrofosmin quantitative gated single-photon emission computed tomography. Three groups of 30 patients each were classified as "no history of myocardial ischemia or cardiomyopathy" (Group A), "history of myocardial infarction" (Group B), and "ischemic heart disease without myocardial infarction history" (Group C). Upon assuming the prone position, the cardiac index and any dyssynchrony worsened in all groups. Ejection fraction changes occurred only in Group B, and diastolic function changes occurred in Groups B and C, but not in Group A. The changes caused by prone positioning were more severe in the patients with poor cardiac function.

CONCLUSIONS

Prone positioning induces significant changes in systolic and diastolic function, as well as dyssynchrony. The negative effects of prone positioning are more severe in patients with poor baseline cardiac function.

Natriuretic peptides and NGAL in heart failure: does a link exist?

In recent years there has been growing interest in the development of new diagnostic tools and particularly in laboratory tests for the identification of heart failure (HF) patients. Because of the rise in HF occurrence, it is necessary to use simple and reliable method to recognize those patients at risk before the onset of the clinical symptoms. To date HF diagnosis remains difficult: its symptoms and signs are often non specific as well as being poor sensitive indicators for HF severity. Throughout the last 10 years published literature has highlighted a boom in the use of biomarkers for HF. Both B-type and N-terminal pro-B-type natriuretic peptides have demonstrated specific role in heart failure diagnosis, as well as risk assessment. A single determination of BNP at any time during the development of chronic heart failure (CHF) provides a clinically useful tool to establish the outcome. Renal dysfunction is often associated with heart failure and predicts adverse clinical outcomes. Many studies have recently suggested the clinical use of serum neutrophil gelatinase-associated lipocalin (NGAL) levels in patients admitted to the hospital for acute HF can be used to estimate the risk of early worsening renal function. This could be potentially applied in clinical practice for early identification of renal dysfunction development in patients with HF. NGAL levels appear also to predict renal dysfunction in patients with chronic HF and preserved renal function. For all these reasons, BNP and NGAL are two emerging tools useful for diagnosis and prognosis in HF. The combination of two laboratory biomarkers could potentially identify patients with more elevated risks of both cardiac hemodynamic impairment and kidney dysfunction.

Clinical features of myocardial triglyceride in different types of cardiomyopathy assessed by proton magnetic resonance spectroscopy: comparison with myocardial creatine

BACKGROUND

Myocardial lipid overstorage may produce cardiomyopathy, leading to dysfunction, but advanced heart failure may cause lipolysis via sympathetic nerve activation. In the failing heart, the creatine kinase system may also be impaired. The aims of this study were to assess myocardial triglyceride (TG) and creatine (CR) in different types of cardiomyopathy and to investigate whether they are related to the severity of cardiac dysfunction.

METHODS AND RESULTS

In patients with hypertrophic cardiomyopathy (HCM, n = 8), dilated cardiomyopathy (DCM, n = 12) or ischemic cardiomyopathy (ICM, n = 10), and normal subjects (NML, n = 22), myocardial TG and CR were evaluated using proton magnetic resonance spectroscopy. To assess cardiac sympathetic nerve activity, myocardial MIBG (a radioactive guanethidine analog) uptake was measured in DCM. Myocardial TG was significantly lower in hypertrophic cardiomyopathy (HCM) (1.92 ± 0.99 μmol/g), but higher in ICM (7.59 ± 4.36 μmol/g) than in NML hearts (4.05 ± 1.94 μmol/g). There was no significant difference in TG between DCM (4.84 ± 6.45 μmol/g) and NML. Myocardial CR in HCM (20.4 ± 8.4 μmol/g), DCM (14.8 ± 4.8 μmol/g), and ICM (19.4 ± 6.3 μmol/g) was significantly lower than that in NML hearts (27.1 ± 4.3 μmol/g). Overall, myocardial CR correlated positively with the severity of heart failure estimated by ejection fraction or myocardial BMIPP (a radioactive fatty acid analog) uptake, but TG did not. In DCM, myocardial TG correlated with body mass index, but not with MIBG uptake.

CONCLUSIONS

Myocardial TG may be related to the specific cause of disease rather than the severity of cardiac dysfunction. In contrast, myocardial CR reflects the severity of heart failure despite different pathoetiologic mechanisms of dysfunction. In DCM, myocardial TG may be affected by an overweight state rather than cardiac sympathetic nerve dysfunction. Thus, myocardial CR has a closer relationship to heart failure severity than does myocardial TG.

Relationship between exercise capacity and cardiac diastolic function assessed by time-volume curve from 16-frame gated myocardial perfusion SPECT

OBJECTIVE

Echocardiographic studies have suggested an association between diastolic dysfunction and exercise intolerance. The aim of this study was to examine the relationship between exercise capacity and left ventricular (LV) function during stress myocardial scintigraphy, and to investigate whether or not this relationship is caused by ischemia during exercise.

METHODS

The studied patients underwent technetium-99m sestamibi quantitative gated SPECT, including treadmill exercise. Myocardial stress images were acquired 30 min after the first tracer injection (370 MBq) during maximal exercise. Three hours later, the second tracer (740 MBq) was injected, and resting images were acquired 30 min after this injection. The presence of ischemia was determined by tracer accumulation. From the same data source, LV diastolic parameters [first third filling fraction (1/3FF), first third filling rate (1/3FR), peak filling rate (PFR) and time to PFR (TPF)], and systolic parameters [ejection fraction (EF), peak ejection rate (PER), time to PER (TPE) and first third ejection fraction (1/3EF)] were analyzed.

RESULTS

Subjects with exercise inability (<6 METs) were excluded. In 45 patients, diastolic parameters 1/3FF, 1/3FR, PFR and TPF correlated significantly with exercise duration (r = 0.32*, 0.37*, 0.37* and -0.40(#), respectively; *p < 0.05, (#) p < 0.01), but systolic parameters EF, PER, TPE and 1/3EF did not. At rest, 1/3FF, PFR and PER were significantly increased, suggesting functional deterioration during exercise. Even after 3 h, 1/3FR, PFR and TPF still correlated significantly with exercise duration (r = 0.29*, 0.36* and -0.30*, respectively; *p < 0.05). Such findings were observed even when the 10 patients who exhibited ischemia during exercise were excluded (1/3FR: r = 0.34*; PFR: r = 0.37*; TPF: r = -0.36*; *p < 0.05, n = 35).

CONCLUSIONS

Our findings suggested that LV diastolic dysfunction, not systolic dysfunction, is associated with limited exercise capacity independent of the occurrence of ischemia.

Clinical significance of diastolic function as an indicator of myocardial ischemia assessed by 16-frame gated myocardial perfusion SPECT

OBJECTIVE

Studies have suggested that ischemia-induced diastolic dysfunction persists longer than systolic dysfunction. We examined whether global left ventricular (LV) diastolic function during stress testing assessed by 16-frame gated myocardial perfusion single-photon emission computed tomography (SPECT) is useful as an indicator of myocardial ischemia.

METHODS

Thirty-nine patients underwent 16-frame technetium-99m (Tc-99m) quantitative gated SPECT (QGS), including treadmill exercise testing for suspected ischemic heart disease. Diastolic parameters of the first-third filling fraction (1/3FF), and the peak filling rate (PFR) were calculated by a time-volume curve from the QGS data.

RESULTS

The patients were divided into four groups, namely, IS, NL, DN, and DD, on the basis of tracer accumulation and the LV ejection fraction (LVEF) at rest. In the IS group (reversible tracer uptake reduction suggesting ischemia; n=11), LVEF, 1/3FF, and PFR after stress were significantly lower than those at rest, whereas in the NL group (normal perfusion; n=10) and DN group (fixed tracer uptake reduction with normal systolic function; EF>or=60% at rest; n=10), LVEF, 1/3FF, and PFR after stress did not differ from those at rest. However, in the DD group (fixed tracer uptake reduction with cardiac dysfunction; EF<60%, average 47.1%; n=8), LVEF, 1/3FF, and PFR were significantly altered after stress.

CONCLUSIONS

Altered global LV diastolic function during stress assessed by 16-frame gated myocardial perfusion SPECT is useful for the detection of myocardial ischemia. However, similar findings are observed in patients with cardiac dysfunction but without detectable ischemia. Our findings do suggest that tests should be performed with caution to determine whether ischemia exists on the basis of altered global LV function after stress in patients with cardiac dysfunction.

Assessment of left ventricular dyssynchrony during development of heart failure by a novel program using ECG-gated myocardial perfusion SPECT

BACKGROUND

A novel program, "cardioGRAF", has been developed to analyze regional left ventricular (LV) systolic/diastolic function and dyssynchrony, so the present study aimed to use it confirm the presence of LV dyssynchrony, and to correlate LV function and dyssynchrony with plasma B-type natriuretic peptide (BNP) levels during the early to advanced stages of heart failure (HF).

METHODS AND RESULTS

Fourteen control subjects (G-C) and 50 patients (New York Heart Association functional class I: G-1, 21 patients; class II: G-2, 15 patients; and class III: G-3, 14 patients) were examined by ECG-gated myocardial perfusion single-photon emission computed tomography, using the new index of dyssynchrony, maximal difference (MD), which is the difference between the earliest and latest temporal parameters among 17 segments. First-third filling rate (FR) and the MD of time to peak FR revealing diastolic dyssynchrony were significantly different between G-C subjects and G-1 patients. Ejection fraction, peak ejection rate, peak FR, MD of time to end-systole, and MD of time to peak ejection rate were significantly correlated with plasma BNP levels.

CONCLUSION

Diastolic dyssynchrony was demonstrated even in the early stage of HF, but, although not correlated with the plasma BNP level, systolic dyssynchrony might affect it.

Comparison of gated SPECT, echocardiography and cardiac magnetic resonance imaging for the assessment of left ventricular ejection fraction and volumes

BACKGROUND

Left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV) can be determined non-invasively by two-dimensional enchocardiography (ECHO), gated sinle photon emission computed tomography (GSPECT) and cardiac magnetic resonance imaging (CMRI). This study was designed to analyze the concordance between LVEF, EDV and ESV values derived from ECHO, GSPECT and CMRI.

METHODS

ECHO, GSPECT and CMRI were performed in a group of 21 patients with suspected coronary artery disease. LVEF, EDV and ESV values were calculated.

RESULTS

The mean LVEF measured with GSPECT, ECHO and CMRI were 55.9+/-17.8%, 55.7+/-16.4% and 56.4+/-15.7%, respectively. The mean EDV measured with GSPECT, ECHO and CMRI were 109.2+/-42.45 mL, 127.5+/-42.2 mL, 91.1+/-38.0 mL, respectively. The mean ESV measured with GSPECT, ECHO and CMRI were 54.2+/-41.2 mL, 59.9+/-37.6 mL and 41.8+/-26.9 mL, respectively. The results of linear regression analysis showed very good correlation between LVEF and ESV values derived from GSPECT, ECHO adn CMRI (r=0.91, r=0.92, r=0.97 for LVEF and r=0.86, r=0-91, r=0.91 for ESV, P<0.01). Good correlations were found between EDV values obtained from GSPECT, ECHO and CMRI (r=0.71, r=0.68, r=0.73, P<0.01). Agreement between these techniques in LVEF values was also good, but not in LV volumes, according to Bland-Altman plots.

CONCLUSIONS

This study showed good overall correlations between LVEF, EDV and ESV values derived from GSPECT, ECHO and CMRI. LVEF obtained from any of these three imaging modalities could be used interchangeably. However, care should be taken in comparing LV volumes.

Assessment of cardiac function in patients with heart disease by quantitative gated myocardial perfusion SPECT

OBJECTIVE

We examined the cardiac function of patients who underwent Tc-99m sestamibi quantitative gated myocardial single photon emission computed tomography with 16-framing data acquisition between January 1, 2004 and March 31, 2006 for an evaluation of suspected or known heart disease in our hospital.

METHODS

In 192 patients aged >or=40 years, the left ventricular (LV) systolic function [parameter: ejection fraction (EF)] and diastolic function [first third filling fraction (1/3FF), peak filling rate (PFR), and time-to-peak filling (TPF)] were estimated by volume curve analysis. In 51 (age >or=60 years) of 192 patients, brachial-ankle pulse wave velocity (baPWV) was also measured.

RESULTS

The correlation between diastolic parameters PFR and 1/3FF was mild (r = 0.28, P < 0.001). On the basis of EF and PFR, 192 patients were divided into four groups: P (preserved LV function), Q (isolated systolic dysfunction, EF < 50%), R (isolated diastolic dysfunction, PFR < 1.8 EDV/s), and S (both dysfunctions). The numbers of patients in P, Q, R, and S groups were 94 (49.0%), 7 (3.6%), 31 (16.1%), and 60 (31.3%), respectively. The 1/3FF correlated weakly but significantly with age (r = -0.16, P < 0.05). The TPF also correlated weakly with age (r = 0.25, P < 0.01), but EF did not. The baPWV, an indicator of cardiovascular stiffness, correlated inversely with 1/3FF (r = -0.59, P < 0.001) or correlated positively with TPF (r = 0.45, P < 0.001), but not with EF.

CONCLUSIONS

Our study suggests that cardiovascular stiffness associated with increased baPWV may contribute to the occurrence of diastolic dysfunction in elderly patients.

A novel clinical indicator using Tc-99m sestamibi for evaluating cardiac mitochondrial function in patients with cardiomyopathies

BACKGROUND

Technetium 99m sestamibi (MIBI) is a technetium-labeled myocardial perfusion agent that is taken up by the myocardial cell in proportion to myocardial regional blood flow and remains fixed in the myocardial cell over a long period of time. Previous studies have suggested that MIBI shows very slow myocardial clearance after its initial uptake in an animal model, which is related to mitochondrial function. This study was designed to test the hypothesis that MIBI washout can be used to evaluate the severity of congestive heart failure in comparison to other clinical parameters in patients with cardiomyopathies.

METHODS AND RESULTS

After administration of MIBI, 61 patients with nonischemic congestive heart failure (49 with dilated cardiomyopathy and 12 with other cardiomyopathies) and 7 normal control subjects were examined by electrocardiography-gated myocardial perfusion single photon emission computed tomography and planar data acquisition in the early and delayed phases (interval of 3 hours). Myocardial MIBI washout rates were calculated from the early and delayed planar images. Left ventricular function (systolic and diastolic) was analyzed by use of QGS data. Plasma levels of B-type natriuretic peptide and iodine 123 metaiodobenzylguanidine (MIBG) parameters were also measured. Patients were followed up for a mean of 12 months (range, 1-19 months). As the severity of the New York Heart Association (NYHA) functional class advanced, the washout rate of MIBI increased (21.6% +/- 2.4% in those with NYHA class I [n = 23], 28% +/- 4% in those with NYHA class II [n = 27], and 35% +/- 5% in those with NYHA class III [n = 10]; P < .05, analysis of variance). The washout rate of MIBI was positively correlated with the level of B-type natriuretic peptide (r = 0.31, P < .05), end-diastolic volume (r = 0.396, P < .01), and end-systolic volume (r = 0.496, P < .01) and was negatively correlated with left ventricular ejection fraction (r = 0.523, P < .01), peak filling rate (r = 0.444, P < .01), and first-third ejection fraction (r = 0.414, P < .01). The parameters of MIBG scintigraphy were calculated as the heart-mediastinum count ratio (1.9 +/- 3) and washout rate (38% +/- 4%). We found a significant relationship between the washout rate of MIBI and the heart-mediastinum count ratio of MIBG (r = 0.51, P < .01). Patients with a higher washout rate of MIBI had a higher cardiac event rate (> or =28%) than those with a lower washout rate (<28%) (P < .05).

CONCLUSIONS

The myocardial washout rate of MIBI is thought to be a novel marker for the diagnosis of myocardial damage or dysfunction, providing prognostic information in patients with congestive heart failure.

Evaluation of cardiac resynchronization therapy in drug-resistant dilated-phase hypertrophic cardiomyopathy by means of Tc-99m sestamibi ECG-gated SPECT

This case describes a 65-year-old male with drug-resistant heart failure. Cardiac resynchronization therapy was performed. We evaluated cardiac function with volume curve differentiation software (VCDiff) from QGS data with Tc-99m sestamibi. Left ventricular parameters during atrial-right ventricular pacing were left ventricular ejection fraction (LVEF) 30%, end-diastolic volume (EDV) 156 ml, end-systolic volume (ESV) 108 ml and peak filling rate 1.12 (EDV/sec). And during dual chamber pacing, those were LVEF 35%, EDV 145 ml and ESV 95 ml and PFR 1.58 (EDV/sec). And during atrial-left ventricular pacing, those were LVEF 36%, EDV 152 ml, ESV 97 ml and peak filling rate (PFR) 1.35 (EDV/sec). Cardiac resynchronization therapy may improve cardiac function as well as dyssynchrony, which could be evaluated non-invasively and accurately by ECG-gated SPECT.

Gated SPECT Findings Revealing Diastolic Dysfunction in Acute Hypothyroidism

PURPOSE

The purpose of this study was to assess left ventricular (LV) function by gated SPECT in acute hypothyroidism.

METHODS

Thirty-eight acute hypothyroid patients without any cardiac disease and 40 healthy controls underwent gated SPECT at rest. Fourteen patients had a second examination during thyroxine replacement therapy. Gated SPECT was performed using Tc-99m sestamibi with 16 frames per cardiac cycle. The LV end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), peak ejection rate (PER), peak filling rate (PFR), and time to peak filling (TTPF) were measured by quantitative gated SPECT (QGS). Systolic wall thickening/motion was determined in 5 myocardial segments.

RESULTS

Hypothyroid patients exhibited a decrease in PFR (222 +/- 52 EDV/s) and prolongation of TTPF (194 +/- 32 msec) as compared with controls (247 +/- 41 EDV/s and 179 +/- 17 msec, respectively; P < 0.05). During thyroxine therapy, the mean values for EDV (74 +/- 21 mL) and PFR (265 +/- 64 EDV/s) increased significantly in 14 follow-up patients (pretreatment values 67 +/- 18 mL and 219 +/- 50 EDV/s, respectively; P < 0.05). A significant difference was detected in the mean TTPF between the thyroxine group and the controls (195 +/- 35 msec vs 179 +/- 17 msec; P < 0.05). No significant differences were found in wall thickening and motion values (P > 0.05).

CONCLUSION

Gated SPECT findings revealed diastolic dysfunction as indicated by a decrease in PFR and a prolongation in TTPF in patients with acute hypothyroidism.