Effects of perindopril on cardiac sympathetic nerve activity in patients with congestive heart failure: comparison with enalapril

Left-atrial volume reduction reflects improvement of cardiac sympathetic nervous function in patients with severe aortic stenosis after transcatheter aortic valve replacement

Trans-catheter aortic valve replacement (TAVR) is an excellent alternative intervention for surgical aortic valve replacement. Cardiac sympathetic nervous (CSN) function and left atrial (LA) volume are both important prognostic factors in patients with aortic stenosis (AS) after TAVR. The relationship between the two clinical factors is unknown, however. This retrospective observational study aimed to assess the correlation between CSN function and LA volume in 48 symptomatic patients with severe AS (median age: 85 years, IQR 82-88 years; 81% female) before and after TAVR. CSN function was assessed by performing ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy before and 6 months after TAVR, and the delayed heart-to-mediastinum ratio (dHMR) and washout rate (WR) were calculated. We also performed transthoracic echocardiography near the same time. TAVR improved the dHMR, WR, and LA volume index (LAVI) (dHMR: median 2.89 [IQR 2.62-3.23] vs. 2.98 [2.49-3.25], p = 0.0182; WR: 28% [24-38] vs. 23% [16-32], p < 0.0001; LAVI: 47.7 mL/m² [37.8-56.3] vs. 41.2 mL/m² [33.7-56.1], p = 0.0024). In multiple linear regression analysis, the percentage change in LAVI from baseline to post-TAVR (∆LAVI%) was an independent predictor of change in dHMR from baseline to post-TAVR (β =  - 0.35, p = 0.0110). In conclusion, LA volume reduction reflected CSN functional improvement after TAVR. In patients with TAVR, ∆LAVI% might be a valuable parameter for evaluating CSN functional recovery.

Cardiac 123I-mIBG Imaging in Heart Failure

Cardiac sympathetic upregulation is one of the neurohormonal compensation mechanisms that play an important role in the pathogenesis of chronic heart failure (CHF). In the past decades, cardiac 123I-mIBG scintigraphy has been established as a feasible technique to evaluate the global and regional cardiac sympathetic innervation. Although cardiac 123I-mIBG imaging has been studied in many cardiac and neurological diseases, it has extensively been studied in ischemic and non-ischemic CHF. Therefore, this review will focus on the role of 123I-mIBG imaging in CHF. This non-invasive, widely available technique has been established to evaluate the prognosis in CHF. Standardization, especially among various combinations of gamma camera and collimator, is important for identifying appropriate thresholds for adequate risk stratification. Interestingly, in contrast to the linear relationship between 123I-mIBG-derived parameters and overall prognosis, there seems to be a "bell-shape" curve for 123I-mIBG-derived parameters in relation to ventricular arrhythmia or appropriate implantable cardioverter defibrillator (ICD) therapy in patients with ischemic CHF. In addition, there is a potential clinical role for cardiac 123I-mIBG imaging in optimizing patient selection for implantation of expensive devices such as ICD and cardiac resynchronization therapy (CRT). Based on cardiac 123I-mIBG data risk models and machine learning, models have been developed for appropriate risk assessment in CHF.

Myocardial innervation imaging: MIBG in clinical practice

123I-metaiodobenzylguanidine (MIBG) is a radiolabeled norepinephrine analog that can be used to investigate myocardial sympathetic innervation. 123I MIBG scintigraphy has been investigated with interest in many disease settings. In patients with systolic heart failure (HF), 123I MIBG scintigraphy can capture functional impairment and rarefaction of sympathetic terminals (which manifest as reduced early and late heart-to-mediastinum [H/M] ratio on planar scintigraphy), and increased sympathetic outflow (which can be visualized as high washout rate). These findings have been consistently associated with a worse outcome: most notably, a phase 3 trial found that patients with a late H/M 1.60 have a higher incidence of all-cause and cardiovascular mortality and life-threatening arrhythmias over a follow-up of less than 2 years. Despite these promising findings, 123I MIBG scintigraphy has not yet been recommended by major HF guidelines as a tool for additive risk stratification, and has then never entered the stage of widespread adoption into current clinical practice. 123I MIBG scintigraphy has been evaluated also in patients with myocardial infarction, genetic disorders characterized by an increased susceptibility to ventricular arrhythmias, and several other conditions characterized by impaired sympathetic myocardial innervation. In the present chapter we will summarize the state-of-the-art on cardiac 123I MIBG scintigraphy, the current unresolved issues, and the possible directions of future research.

Bioequivalence study of two perindopril tert-butylamine tablet formulations in healthy Chinese subjects under fasting and fed conditions: A randomized, open-label, single-dose, crossover trial

BACKGROUND

To evaluate the bioequivalence between test and reference formulations of perindopril tert-butylamine under fasting and fed conditions and to assess their pharmacokinetic (PK) and safety profiles.

METHOD

A randomized, open-label, single-dose, crossover trial was conducted in healthy Chinese subjects. Test or reference perindopril tert-butylamine tablets (4 mg) were randomly given to subjects under fasting (2-period crossover, with an administration sequence of test tablet (T), reference tablet (R) or RT) and fed (4-period crossover, with an administration sequence of TRTR or RTRT) conditions, while each single administration was followed by a 14-day washout period. The plasma concentrations and corresponding non-compartmental PK parameters of perindopril and perindoprilat were determined. The two formulations were considered to be bioequivalent if the 90 % confidence intervals (CIs) of the geometric mean (GM) ratio (test/reference) for C_max, AUC_0-t, and AUC_0-∞ (perindopril) was both within the range of 80-125 %. Safety assessments including vital signs, physical examination, laboratory examination, 12-lead ECG and reports of treatment emergent adverse events (TEAEs) were carefully documented.

RESULTS

A total of 64 subjects (32 in each trial) were randomized and all completed the trials. Regardless of fasting or fed trials, the PK characteristics of perindopril and perindoprilat for the test formulation were similar to those of the reference formulation (all P > 0.05). The 90 % CIs of the geometric mean (GM) ratio for C_max, AUC_0-t, and AUC_0-∞, respectively, were 92.86-106.81 %, 98.44-102.88 % and 98.48-103.02 % under the fasting condition and 90.64-110.04 %, 96.95-101.90 % and 96.83-101.78 % under the fed condition, which were both within the pre-specified range of 80-125 %. A total of 10 (31.3 %) fasted subjects and 11 (34.4 %) fed subjects experienced 11 and 24 TEAEs, respectively, all of which were within the severity of grade 1. The incidence of TEAEs and drug-related TEAEs were similar between test and reference formulations (all P > 0.05) and no serious TEAEs or deaths occurred during the trials.

CONCLUSIONS

The test and reference formulations of perindopril tert-butylamine tablets (4 mg) were bioequivalent and well tolerated in healthy Chinese subjects under fasting and fed conditions.

Assessment of therapeutic effects of statin on cardiac sympathetic nerve activity and cardiac events in patients with ischemic cardiomyopathy and mild to moderate heart failure

INTRODUCTION

We determined whether statin therapy improved cardiac sympathetic nerve activity as evaluated using iodine-123-metaiodobenzylguanidine (I-MIBG) scintigraphy, and whether this therapy affects prognosis in patients with ischemic cardiomyopathy.

PATIENTS AND METHODS

This study was a subanalysis of our previous report of the result that the serial I-MIBG scintigraphic studies were the most useful prognostic indicator in patients with heart failure. Patients with heart failure [left ventricular ejection fraction (LVEF) <45%] but no cardiac events for at least 5 months before the study were identified according to their history of decompensated acute heart failure requiring hospitalization. The patients underwent I-MIBG scintigraphy and echocardiography immediately before hospital discharge and after 6 months. The % denervation, heart/mediastinum count ratio, and washout rate were determined from the I-MIBG scintigraphy, and the left ventricular end-diastolic volume, left ventricular end-systolic volume, and LVEF were also determined from echocardiography. We selected 76 patients with old myocardial infarction without active ischemia and used propensity score matching to compare patients who received oral statin (n=38) with those who did not (n=38). The patients were followed up for a median of 4.74 years, with the primary and secondary study end points defined as incidences of fatal cardiac events and major adverse cardiac events (MACEs), respectively.

RESULTS

After treatment, the I-MIBG scintigraphic and echocardiographic parameters were improved in the statin and nonstatin groups. However, the extent of change in the % denervation was -12.3±10.3 and -6.2±9.6 (P<0.01), whereas that in the heart/mediastinum count ratio was 0.19±0.14 and 0.08±0.15 (P<0.01), and that in washout rate was -8.1±7.2 and -0.5±9.2% (P<0.01). The extent of change in left ventricular end-diastolic volume, left ventricular end-systolic volume, and LVEF in the statin group tended to exceed than in the nonstatin group, but these changes were not statistically significant. Of the 76 patients, 18 experienced fatal cardiac events and 32 experienced MACEs during the study. Multivariate Cox regression analyses revealed that the nonstatin therapy was a significant predictor of both cardiac death and MACEs in our patients. On Kaplan-Meier analysis, the rates of freedom from cardiac death or MACEs were significantly higher in the statin group than those in the nonstatin group (all, P<0.05).

CONCLUSION

Statin therapy improved cardiac sympathetic nerve activity in patients with ischemic cardiomyopathy and mild to moderate heart failure. Furthermore, statin is potentially effective for reducing cardiac events in these patients.

Transcatheter Aortic Valve Implantation Improves Cardiac Sympathetic Nerve Activity on 123I-Metaiodobenzylguanidine Myocardial Scintigraphy in Severe Aortic Valve Stenosis

BACKGROUND

There is a consensus that overactivation of the cardiac sympathetic nervous system (CSN) proportionately increases the severity of heart failure and is accompanied by worse prognosis. Because it is unknown whether patients with aortic valve stenosis (AS) have similar CSN activation, we investigated the effect of transcatheter aortic valve implantation (TAVI).Methods and Results:We enrolled 31 consecutive patients with AS treated by TAVI. ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was performed at baseline and at 2 weeks after TAVI. At baseline, the early heart-mediastinum ratio (H/M) was within normal limits (3.0±0.5), but the delayed H/M was low (2.6±0.6) and the washout rate (WR) was high (34±13%). WR negatively correlated with aortic valve area (r=-0.389, P<0.01) and cardiac output (r=-0.595, P<0.01) and positively correlated with norepinephrine (r=0.519, P<0.01) and log NT-proBNP level (r=0.613, P<0.01). After TAVI, there were significant decreases in the norepinephrine level (366±179 ng/mL vs. 276±125 ng/mL, P<0.01) and WR (34±13 vs. 26±11%, P<0.01).

CONCLUSIONS

The WR of MIBG was a useful marker of CSN activity and severity of AS. Immediate improvement of CSN activity after TAVI implied that AS hemodynamics per se enhanced CSN.

Impact of medications on mIBG uptake, with specific attention to the heart: Comprehensive review of the literature

BACKGROUND

A critical review of the literature on drug interactions with mIBG uptake was performed to allow formulation of contemporary guidance regarding withholding medications prior to clinical imaging studies.

METHODS

Published information was extracted on the experimental system used, the quantitative characteristics of the measurements, and whether any data directly examining cardiac tissues were included. Level of evidence for each medication category was assessed on a qualitative scale of very low, low, medium, or high. Strength of medication effect for inhibition of mIBG uptake was judged as none, weak, moderate, or strong.

RESULTS

The only medications for which level of evidence was judged high were labetalol and reserpine. Level of evidence was judged medium for tricyclic antidepressants, calcium channel blockers, and antiarrhythmics (specifically amiodarone). Evidence was judged sufficient to recommend withholding labetalol and the tricyclic antidepressants prior to mIBG cardiac imaging. Mechanistic evidence was sufficient to suggest consideration of withdrawal of sympathomimetic amines and serotonin-norepinephrine reuptake inhibitors (SNRIs).

CONCLUSIONS

As there is strong evidence for inhibition of mIBG uptake in only a small number of compounds, clinical decisions regarding withdrawal of concomitant medications should be individualized by considering the potential consequences of a false-positive (artificially low cardiac uptake) imaging result.

Introduction to cardiac neuronal imaging: a clinical perspective

Procedures for noninvasive and minimally invasive imaging of cardiac neurons and neuronal function using radiolabeled compounds were developed in the second half of the 20th century. The foundation for these procedures was several centuries of research that identified the structural components of the autonomic nervous system and explored the means by which neurotransmitters such as acetylcholine and norepinephrine contributed to neuronal control of target organ effector cells. This article provides a brief clinical overview of modern approaches to the assessment of cardiac neurons as an introduction to the in-depth articles on the current status of cardiac neuronal imaging presented in this supplement.

123I-MIBG SPECT for Evaluation of Patients with Heart Failure

Heart failure (HF) is characterized by activation of the sympathetic cardiac nerves. The condition of cardiac sympathetic nerves can be evaluated by (123)I-metaiodobenzylguanidine ((123)I-MIBG) imaging. Most cardiac (123)I-MIBG studies have relied on measurements from anterior planar images of the chest. However, it has become progressively more common to include SPECT imaging in clinical and research protocols. This review examines recent trends in (123)I-MIBG SPECT imaging and evidence that provides the basis for the increased use of the procedure in the clinical management of patients with HF. (123)I-MIBG SPECT has been shown to be complementary to planar imaging in patients with HF in studies of coronary artery disease after an acute myocardial infarction. Moreover, (123)I-MIBG SPECT has been used in numerous studies to document regional denervation for arrhythmic event risk assessment. For better quantification of the size and severity of innervation abnormalities in (123)I-MIBG SPECT, programs and protocols specifically for (123)I have been developed. Also, the introduction of new solid-state cameras has created the potential for more rapid SPECT acquisitions or a reduction in radiopharmaceutical activity. Although PET imaging has superior quantitative capabilities, (123)I-MIBG SPECT is, for the foreseeable future, the only widely available nuclear imaging method for assessing regional myocardial sympathetic innervation.

Evaluation of cardiac sympathetic nerve activity and aldosterone suppression in patients with acute decompensated heart failure on treatment containing intravenous atrial natriuretic peptide

PURPOSE

Aldosterone prevents the uptake of norepinephrine in the myocardium. Atrial natriuretic peptide (ANP), a circulating hormone of cardiac origin, inhibits aldosterone synthase gene expression in cultured cardiocytes. We evaluated the effects of intravenous ANP on cardiac sympathetic nerve activity (CSNA) and aldosterone suppression in patients with acute decompensated heart failure (ADHF).

METHODS

We studied 182 patients with moderate nonischemic ADHF requiring hospitalization and treated with standard therapy containing intravenous ANP and 10 age-matched normal control subjects. ANP was continuously infused for >96 h. In all subjects, delayed total defect score (TDS), heart to mediastinum ratio, and washout rate were determined by 123I-metaiodobenzylguanidine (MIBG) scintigraphy. Left ventricular (LV) end-diastolic volume, end-systolic volume, and ejection fraction were determined by echocardiography. All patients with acute heart failure (AHF) were examined once within 3 days and then 4 weeks after admission, while the control subjects were examined only once (when their hemodynamics were normal). Moreover, for 62 AHF patients, plasma aldosterone concentrations were measured at admission and 1 h before stopping ANP infusion.

RESULTS

123I-MIBG scintigraphic and echocardiographic parameters in normal subjects were more favorable than those in patients with AHF (all p < 0.001). After treatment, all these parameters improved significantly in AHF patients (all p < 0.001). We also found significant correlation between percent changes of TDS and aldosterone concentrations (r = 0.539, p < 0.001) in 62 AHF patients.

CONCLUSION

The CSNA and LV performance were all improved in AHF patients. Furthermore, norepinephrine uptake of myocardium may be ameliorated by suppressing aldosterone production after standard treatment containing intravenous ANP.

Effects of statin therapy on cardiac sympathetic nerve activity and left ventricular remodeling in patients with chronic heart failure: a propensity score-matched analysis

Statin therapy reduces enhanced cardiac sympathetic nerve activity (CSNA) in patients with heart disease, and prevents left ventricular (LV) remodeling in chronic heart failure (CHF) patients. We sought to evaluate the effects of statin therapy on CSNA, as evaluated by I-metaiodobenzylguanidine (MIBG) scintigraphy, and LV remodeling in CHF patients. This study was sub-analysis of our previous report of the result that the serial I-MIBG studies were the most useful prognostic indicator in CHF patients. Patients with CHF (n = 208; left ventricular ejection fraction <45%) but no cardiac events for at least 5 months before the study, were identified according to their history of decompensated acute heart failure requiring hospitalization. The patients underwent I-MIBG scintigraphy and echocardiography immediately before hospital discharge and after 6 months. The delayed % denervation, delayed heart/mediastinum count (H/M) ratio, and washout rate (WR) were determined by I-MIBG scintigraphy. The LV end-diastolic volume (EDV) and end-systolic volume (ESV) were also determined by echocardiography. We selected 164 patients and used propensity score matching to compare patients who received oral statin (n = 82), and those who did not (n = 82).The changes in I-MIBG scintigraphic parameters improved, and in echocardiographic LVEDV and LVESV reduced in the statin group compared with those in the non-statin group. Moreover, there were significant correlations between changes in the I-MIBG scintigraphic findings and those in the LVEDV (% denervation, r = 0.534, P < 0.001; H/M ratio, r =  -0.516, P < 0.001; and WR, r = 0.558, P < 0.001); or the LVESV (% denervation, r = 0.479, P < 0.001; H/M ratio, r =  -0.450, P < 0.001; and WR, r = 0.520, P < 0.001) in the statin group. In contrast, there was no relationship between these parameters in the non-statin group.Statin therapy not only improved CSNA, but also reduced LV volume, in other wards, prevented LV remodeling in CHF patients.

Not all angiotensin-converting enzyme inhibitors are equal: focus on ramipril and perindopril

Angiotensin-converting enzyme (ACE) inhibitors are a heterogeneous class, varying in pharmacologic properties, which have different therapeutic impacts on patient profiles, including lipophilicity, tissue-ACE binding, duration of action, half-life, and increased bradykinin availability. Among the ACE inhibitor class, the agent perindopril, in particular, has pleiotropic effects that are not equally shared by other ACE inhibitors, including bradykinin site selectivity and subsequent enhancement of nitric oxide and inhibition of endothelial cell apoptosis. Moreover, there is a large amount of evidence to suggest that perindopril therapy may reduce cardiovascular event rates in patients, yet perindopril is rarely prescribed in the United States. Ramipril is another ACE inhibitor with both a favorable clinical profile and impressive outcomes data. Our review compares the pharmacologic and trial data among perindopril, ramipril, and other ACE inhibitors. In patients with or at high risk for coronary heart disease who do not have heart failure, or in patients with heart failure with preserved ejection fraction, perindopril should be among the preferred treatment agents in the ACE inhibitor class. Ramipril has an impressive track record of improving cardiovascular outcomes, too, and should be considered a preferred agent among the ACE inhibitor class.

Effects of oral nicorandil therapy on sympathetic nerve activity and cardiac events in patients with chronic heart failure: subanalysis of our previous report using propensity score matching

PURPOSE

Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, improves cardiac sympathetic nerve activity (CSNA) in patients with ischaemic heart disease. However, the long-term effects on both CSNA, as evaluated by (123)I-metaiodobenzylguanidine (MIBG) scintigraphy, and prognosis have not been determined in patients with chronic heart failure (CHF).

METHODS

This study was a subanalysis of our previous results that serial (123)I-MIBG scintigraphic studies are the most useful prognostic indicator in CHF patients. The study group comprised 208 patients with CHF (left ventricular ejection fraction <45 %) but no cardiac events for at least 5 months identified on the basis of a history of decompensated acute heart failure requiring hospitalization. These patients underwent (123)I-MIBG scintigraphy and echocardiography just before leaving the hospital and again 6 months later. We selected 170 patients and used propensity propensity score matching to compare patients who received oral nicorandil (85 patients) and those who did not (85 patients). The patients were followed up for a median of 5.03 years, with the primary and secondary study end-points defined as the occurrence of a fatal cardiac event and a major adverse cardiac event (MACE), respectively.

RESULTS

After treatment, the extent of changes in (123)I-MIBG scintigraphic and echocardiographic parameters in the nicorandil group were more favourable than in those not receiving nicorandil. Of the 170 patients, a fatal cardiac event occurred in 42, and a MACE in 68 during the study. Multivariate Cox regression analyses revealed that no nicorandil treatment was a significant predictor of both cardiac death and MACE in our patients with CHF. On Kaplan-Meier analysis, the rates of freedom from cardiac death or from MACE in the nicorandil group were significantly higher than in those not receiving nicorandil (all p<0.05).

CONCLUSION

Long-term nicorandil treatment improves CSNA and left ventricular parameters in patients with CHF. Furthermore, this agent is potentially effective for reducing the incidence of cardiac events in patients with CHF.

The effect of long-term left ventricular assist device support on myocardial sympathetic activity in patients with non-ischaemic dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) patients have abundant levels of norepinephrine secondary to failure of the norepinephrine transporter uptake mechanism. Little is known about the effects of an LV assist device (LVAD) on cardiac sympathetic innervations and norepinephrine transporter dysfunction. This study examines the effects of continuous-flow HeartMate II LVAD on cardiac sympathetic innervations using [(123)I]metaiodobenzylguanidine ([(123)I]MIBG) nuclear imaging.

METHODS AND RESULTS

After injecting 431 ± 21 MBq of [(123)I]MIBG, planar scintigraphy was performed at 15 min and 4 h in 14 consecutive non-diabetic non-ischaemic DCM patients. Scans were executed early post-LVAD implantation (T1) and prior to either device explantation for myocardial recovery or transplant listing (T2). [(123)I]MIBG measured parameters included early and delayed heart-mediastinum (H/M) ratios and washout rate (W/O). Catecholamine levels were measured using liquid chromatography-mass spectrometry. Following 208.4 ± 85.5 days of LVAD support, both early and delayed H/M ratios increased by 42.1% (P < 0.001) and 54.7% (P < 0.001), respectively. The W/O rate decreased by 46% (P = 0.003). Plasma norepinephrine, epinephrine, and dopamine decreased significantly in correlation with [(123)I]MIBG parameters. Ten patients had recovered and had their device explanted as they had demonstrated a higher percentage change in delayed H/M ratio, W/O rate, and norepinephrine levels. Linear regression analysis revealed a strong correlation between percentage changes in both norepinephrine and epinephrine and myocardial recovery.

CONCLUSION

Combination therapy with LVAD and drug resulted in enhancement of [(123)I]MIBG uptake in DCM patients.

Relationship between late ventricular potentials and myocardial 123I-metaiodobenzylguanidine scintigraphy in patients with dilated cardiomyopathy with mild to moderate heart failure: results of a prospective study of sudden death events

PURPOSE

Late ventricular potentials (LPs) are considered to be useful for identifying patients with heart failure at risk of developing ventricular arrhythmias. (123)I-metaiodobenzylguanidine (MIBG) scintigraphy, which is used to evaluate cardiac sympathetic activity, has demonstrated cardiac sympathetic denervation in patients with malignant ventricular tachyarrhythmias. This study was undertaken to clarify the relationship between LPs and (123)I-MIBG scintigraphy findings in patients with dilated cardiomyopathy (DCM).

METHODS

A total of 56 patients with DCM were divided into an LP-positive group (n = 24) and an LP-negative group (n = 32). During the compensated period, the delayed heart/mediastinum count (H/M) ratio, delayed total defect score (TDS), and washout rate (WR) were determined from (123)I-MIBG images and plasma brain natriuretic peptide (BNP) concentrations were measured. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and left ventricular ejection fraction (LVEF) were simultaneously determined by echocardiography.

RESULTS

LVEDV, LVESV, LVEF and plasma BNP concentrations were similar in the two groups. However, TDS was significantly higher (35 ± 8 vs. 28 ± 6, p < 0.005), the H/M ratio was significantly lower (1.57 ± 0.23 vs. 1.78 ± 0.20, p < 0.005), and the WR was significantly higher (60 ± 14% vs. 46 ± 12%, p < 0.001) in the LP-positive than in the LP-negative group. The average follow-up time was 4.5 years, and there were nine sudden deaths among the 56 patients (16.1%). In logistic regression analysis, the incidences of sudden death events were similar in those LP-negative with WR <50%, LP-negative with WR ≥ 50% and LP-positive with WR <50% (0%, 10.0% and 14.3%, respectively), but was significantly higher (41.2%) in those LP-positive with WR ≥ 50% (p < 0.01, p < 0.05, and p < 0.05, respectively).

CONCLUSION

The present study demonstrated that the values of cardiac (123)I-MIBG scintigraphic parameters were worse in LP-positive DCM patients than in LP-negative DCM patients. Furthermore, in LP-positive DCM patients with a high WR, the incidence of sudden death events was higher than that in other subgroups of DCM patients.

Effects of mineralocorticoid receptor antagonist spironolactone on cardiac sympathetic nerve activity and prognosis in patients with chronic heart failure

BACKGROUND

Aldosterone prevents norepinephrine uptake and promotes structural remodeling of the heart. Spironolactone is well known to have an anti-aldosteronergic effect, and this agent could improve cardiac sympathetic nerve activity (CSNA) in patients with chronic heart failure (CHF). On the other hand, we previously reported that the delta washout rate (WR) determined from serial (123)I-MIBG scintigraphic studies is the best currently available prognostic value in patients with CHF.

METHODS

In total 208 patients with CHF (left ventricular ejection fraction [LVEF] <45%), but no cardiac events for at least 5 months, were identified on the basis of a history of decompensated acute heart failure requiring hospitalization. These patients underwent (123)I-MIBG scintigraphy and echocardiography just before leaving the hospital and after 6 months of treatment. The patients were retrospectively divided into a spironolactone (n=82) and a non-spironolactone (n=126) group.

RESULTS

The extents of changes in (123)I-MIBG scintigraphic and echocardiographic parameters in the spironolactone group were significantly better than those in the non-spironolactone group. Of the 208 patients, 56 experienced fatal cardiac events during the study. The mean follow-up period was 4.45+/-1.82 years. On Kaplan-Meier analysis, the rate freedom from cardiac death was 81.7% (67/82) in the spironolactone group and 67.5% (85/126) in the non-spironolactone group (P<0.05). Moreover, stepwise multivariate analyses showed spironolactone therapy to have the most independent and significant negative relationship with delta-WR, during the period from hospital discharge until 6 months after starting treatment, in patients with CHF (P<0.001).

CONCLUSIONS

Spironolactone treatment improves CSNA and prevents LV remodeling in patients with CHF. Furthermore, this agent is potentially effective for reducing the incidence of fatal cardiac events in CHF patients.

Serial cardiac 123I-metaiodobenzylguanidine scintigraphic studies are more useful for predicting cardiac death than one-time scan in patients with chronic heart failure: sub-analysis of our previous report

BACKGROUND

Many studies have shown a one-time ¹²³I-metaiodobenzylguanidine (MIBG) scan during a stable period to be useful for determining the prognosis of patients with chronic heart failure (CHF). However, we recently reported that the delta washout rate (WR) determined from serial ¹²³I-MIBG scintigraphic studies is the best prognostic value in patients with CHF.

METHODS

A total of 208 patients with CHF (left ventricular ejection fraction <45%), but no cardiac events for at least 5 months, were identified on the basis of a history of decompensated acute heart failure requiring hospitalization. The patients underwent ¹²³I-MIBG scintigraphy and echocardiography just before leaving the hospital and after 6 months of treatment. We evaluated two models for predicting cardiac death using the Cox proportional hazards regression analysis. In addition to clinical characteristics, New York Heart Association functional class and pharmacotherapy, one model included variables of baseline scintigraphic and echocardiographic parameters (model A), and the other model included those of delta (i.e. follow-up minus baseline) scintigraphic and echocardiographic parameters (model B).

RESULTS

Of the 208 patients, 56 experienced fatal cardiac events during the study. In model A, a Cox proportional hazards analysis showed baseline WR ≥50% to be the only independent predictor of cardiac death (hazard ratio=2.335, 95% confidence interval=1.142-4.774, P=0.020). In model B, delta-WR≥-5% was the only incremental predictor of cardiac death (hazard ratio=4.444, 95% confidence interval=1.511-13.069, P=0.009). The survival rates of patients with a delta-WR of less than -5% were significantly higher for those with a baseline WR of less than 50% (P=0.036). Moreover, high delta-WR was the best predictor compared with single scan, single echocardiography, and their combination evaluated by the global χ² analysis.

CONCLUSION

Baseline WR and delta-WR obtained from ¹²³I-MIBG scintigraphy can be used as independent predictors of cardiac death, and two ¹²³I-MIBG scintigraphic studies are more useful than a one-time scan in stabilized patients with CHF.

Response of cardiac sympathetic nerve activity to intravenous irbesartan in heart failure

To determine the effect of irbesartan treatment on resting levels and arterial baroreflex control of cardiac sympathetic nerve activity (CSNA) in heart failure (HF), we studied conscious normal sheep and sheep with HF induced by rapid ventricular pacing for 8-10 wk (n = 7 per group). In HF, there is a large increase in CSNA that is detrimental to outcome. The causes of this increase in CSNA and the effect of angiotensin receptor blockers on CSNA in HF are unclear. CSNA, arterial blood pressure, heart rate (HR), and arterial baroreflex curves were recorded during a resting period and after 90 min of irbesartan infusion (12 mg.kg(-1).h(-1) iv). This dose of irbesartan abolished the pressor response to intravenous ANG II infusion but caused only a slight decrease in the pressor response to centrally administered ANG II. In HF, there was a large increase in CSNA (from 44 +/- 3 to 87 +/- 3 bursts/100 heartbeats). Irbesartan reduced arterial pressure in the normal and HF groups, but the usual baroreflex-mediated increases in CSNA and HR were prevented. This resulted from a significant leftward shift in the CSNA and HR baroreflex curves in both groups. Irbesartan also decreased the sensitivity of the arterial baroreflex control of CSNA. Short-term treatment with an angiotensin receptor blocker, at a dose that abolished the response to circulating, but not central, ANG II, prevented the reflex increase in CSNA in response to the drug-induced fall in arterial pressure.

Beneficial effect of perindopril on cardiac sympathetic nerve activity and brain natriuretic peptide in patients with chronic heart failure: comparison with enalapril

BACKGROUND

In patients with chronic heart failure (CHF), it remains unclear whether perindopril is more cardioprotective than enalapril.

METHODS AND RESULTS

Forty-five stable CHF outpatients undergoing conventional therapy including enalapril therapy were randomized to 2 groups [group I (n=24): continuous enalapril treatment; group II (n=21): enalapril was changed to perindopril]. Cardiac sympathetic nerve activity was evaluated using cardiac 123I-metaiodobenzylguanidine (MIBG) scintigraphy, hemodynamic parameters and neurohumoral factors before and 6 months after treatment. There was no difference in baseline characteristics between the 2 groups. In group I, there were no changes in MIBG parameters, left ventricular ejection fraction (LVEF) or plasma level of brain natriuretic peptide (BNP). In contrast, in group II the delayed heart/mediastinum count ratio was significantly increased (2.0+/-0.07 vs 2.15+/-0.07, p=0.013) and the washout rate was significantly decreased (33.0+/-1.4 vs 30.5+/-1.2, p=0.030) after 6 months compared with the baseline value. In addition, LVEF was significantly increased and the plasma BNP level was significantly decreased.

CONCLUSION

These findings suggest that for the treatment of CHF, perindopril is superior to enalapril with respect of cardiac sympathetic nerve activity and BNP.

Prognostic value of serial cardiac 123I-MIBG imaging in patients with stabilized chronic heart failure and reduced left ventricular ejection fraction

Many studies have shown that a one-time 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphic study during a stable period is useful for determining the prognosis of patients with chronic heart failure (CHF). However, the findings from this imaging modality are well known to be improved by medical treatment for heart failure. Accordingly, this study was performed to determine whether serial 123I-MIBG scintigraphic studies represent a reliable prognostic marker for patients with CHF.

METHODS

A total of 208 patients with CHF (left ventricular ejection fraction [LVEF] < 45%) and with no cardiac events for at least 5 mo were identified on the basis of a history of decompensated acute heart failure requiring hospitalization. The delayed percentage of denervation (% denervation), delayed heart-to-mediastinum count (H/M) ratio, and washout rate (WR) were determined from the patients' 123I-MIBG images just before they left the hospital and after they had received 6 mo of treatment. The left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and LVEF were also determined by echocardiography at the same time points.

RESULTS

Of the 208 patients, 56 experienced fatal cardiac events during the study. The mean follow-up period was 4.45 +/- 1.82 y. The baseline H/M ratio and WR; follow-up % denervation, H/M ratio, and WR; Delta-% denervation, H/M ratio, and WR; baseline LVEF; follow-up LVEDV, LVESV, and LVEF; and Delta-LVEDV, Delta-LVESV, and Delta-LVEF were significantly worse in the cardiac death group. A Cox regression analysis showed that the Delta-WR was an independent predictor of cardiac death. Moreover, sudden death occurred in 13 of the 56 patients with cardiac death. A Cox regression analysis also showed that the Delta-WR was an incremental predictor of sudden death. The cardiac death-free rate and sudden death-free rate were significantly higher in patients with Delta-WR less than -5% and Delta-WR less than -2% than in patients with Delta-WR greater than or equal to -5% and Delta-WR greater than or equal to -2%.

CONCLUSION

Delta-WR obtained from serial 123I-MIBG scintigraphic studies can be useful for predicting cardiac death and sudden death in stabilized patients with CHF.

Neuronal imaging using SPECT

(123)I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy is one of only a few methods available for objective evaluation of cardiac sympathetic function at the clinical level. Disorders of cardiac sympathetic function play an important role in various heart diseases, and MIBG provides an abundance of useful information for the evaluation of severity, prognosis and therapeutic effects; this is particularly useful in cases of heart failure, ischaemic heart disease and arrhythmic disease. On the other hand, the quantitative indices for MIBG differ between institutions, and evidence has not been sufficiently well established for MIBG scintigraphy when compared with myocardial perfusion imaging in ischaemic heart diseases. In consideration of these difficulties, this review provides fundamental information regarding MIBG, its usefulness for various diseases and future difficulties.

Neuronal imaging using SPECT

BACKGROUND

123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy is one of only a few methods available for objective evaluation of cardiac sympathetic function at a clinical level. Disorders in cardiac sympathetic function play an important role in various heart diseases, and MIBG provides an abundance of useful information for evaluation of disease severity, prognosis, and therapeutic effects; this information is of particular value in patients with heart failure, ischemic heart diseases, or arrhythmic disorders. On the other hand, the quantitative indices for MIBG differ between institutions, and evidence has not been sufficiently well established for MIBG, compared with myocardial perfusion imaging, in ischemic heart diseases.

REVIEW

In view of these difficulties, this review provides fundamental information regarding MIBG, its usefulness for various diseases and future difficulties.

Effects of Intravenous Atrial Natriuretic Peptide on Cardiac Sympathetic Nerve Activity and Left Ventricular Remodeling in Patients With First Anterior Acute Myocardial Infarction

OBJECTIVES

We sought to evaluate the effects of atrial natriuretic peptide (ANP) on cardiac sympathetic nerve activity (CSNA) and left ventricular (LV) remodeling in patients with first anterior acute myocardial infarction (AMI) after primary coronary angioplasty.

BACKGROUND

The activation of the renin-angiotensin-aldosterone system (RAAS) prevents the uptake of norepinephrine in the myocardium. Atrial natriuretic peptide, a circulating hormone of cardiac origin, has vasodilatory and diuretic properties, and can inhibit the RAAS.

METHODS

We studied 50 patients with first anterior AMI who were randomly assigned to receive ANP (group A) or isosorbide dinitrate (group B) before and after primary coronary angioplasty. The ANP or ISDN was continuously infused >48 h. The extent score (ES) was determined from 99mTc-pyrophosphate scintigraphy to evaluate the area of initial myocardial damage 3 to 5 days after primary angioplasty. The LV end-diastolic volume (LVEDV) and LV ejection fraction (LVEF) were determined by left ventriculography 2 weeks later. The delayed heart/mediastinum count (H/M) ratio, delayed total defect score (TDS), and washout rate (WR) were determined from 123I-meta-iodobenzylguanidine scintigraphy after 3 weeks.

RESULTS

After primary angioplasty, age, gender, risk factors, peak serum creatine phosphokinase concentration, recanalization time, and ES were similar in the 2 groups. However, in group A (n = 25), the TDS was significantly lower (34 +/- 8 vs. 41 +/- 8; p < 0.05), the H/M ratio was significantly higher (1.96 +/- 0.18 vs. 1.74 +/- 0.23; p < 0.05), and the WR was significantly lower (35 +/- 8% vs. 44 +/- 12%; p < 0.005) than in group B (n = 25). Moreover, the LVEDV and LVEF in group A were better than in group B (LVEDV: 85.5 +/- 28.5 ml vs. 106.3 +/- 39.4 ml [p < 0.05]; LVEF: 47.9 +/- 10.2% vs. 41.5 +/- 11.8% [p < 0.05]).

CONCLUSIONS

Intravenous ANP improves CSNA and prevents LV remodeling in patients with first anterior AMI.

The effects of medications on circulating levels of cardiac natriuretic peptides

Circulating cardiac natriuretic peptide levels are being used increasingly in a range of clinical circumstances. Since it is evident that drugs used in the treatment of cardiovascular disorders can modulate natriuretic peptide levels, we here review the literature documenting these effects. Diuretics, blockers of the renin-angiotensin system, vasodilator agents, dopamine-like agonists, amiodarone, and perhaps allopurinol and statins suppress natriuretic peptide levels, most obviously in heart failure. Beta-blockers stimulate natriuretic peptide concentrations in hypertensive subjects, whereas in heart failure they have little effect or are stimulatory in the short term and inhibitory with sustained therapy. Digitalis compounds and aspirin tend to increase natriuretic peptide levels, and calcium channel blocking agents have varying effects depending on the individual drug and duration of administration. The effects of other drugs are less clear. Additional information is needed regarding the effects of medications along with dissection of the role of altered cardiac secretion versus changes in plasma clearance as explanation for drug-induced perturbations in natriuretic peptide concentrations. In the meantime, clinicians need to consider the known effects of medications when interpreting plasma levels of the cardiac natriuretic peptides.

Effects of torasemide on cardiac sympathetic nerve activity and left ventricular remodelling in patients with congestive heart failure

OBJECTIVE

To determine the effect of torasemide, a loop diuretic with antialdosteronergic properties, compared with furosemide on cardiac sympathetic nerve activity in patients with congestive heart failure (CHF).

METHODS

40 patients with non-ischaemic CHF (left ventricular ejection fraction (LVEF) < 45%) were randomly assigned to torasemide (4-8 mg/day; n = 20) or furosemide (20-40 mg/day; n = 20). All patients were also treated with angiotensin-converting enzyme inhibitor. The delayed heart to mediastinum count (H/M) ratio, delayed total defect score (TDS) and washout rate were determined from iodine-123 meta-iodobenzylguanidine measured before and 6 months after treatment. Left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV) and LVEF were also determined by echocardiography.

RESULTS

After treatment, in patients receiving torasemide, TDS decreased from 44 (8) to 36 (8) (p < 0.001), H/M ratio increased from 1.61 (0.19) to 1.77 (0.24) (p < 0.001), and washout rate decreased from 52 (12)% to 41 (14)% (p = 0.001). In addition, LVEDV decreased from 173 (22) ml to 147 (30) ml (p < 0.001) and LVESV decreased from 117 (19) ml to 95(24) ml (p < 0.001). Although LVEF tended to increase, the change was not significant (from 31 (7)% to 34 (7)%, NS). Conversely, these parameters did not change significantly in patients receiving furosemide. Moreover, percentage change of TDS was significantly correlated with percentage change of LVEDV (r = 0.473, p < 0.05) and of LVESV (r = 0.579, p < 0.01) after torasemide treatment.

CONCLUSION

These findings indicate that torasemide treatment can ameliorate cardiac sympathetic nerve activity and left ventricular remodelling in patients with CHF.

Comparative effects of valsartan and enalapril on cardiac sympathetic nerve activity and plasma brain natriuretic peptide in patients with congestive heart failure

OBJECTIVE

To evaluate the effects of valsartan on cardiac sympathetic nerve activity, plasma brain natriuretic peptide (BNP) concentration, cardiac function, and symptoms in patients with congestive heart failure (CHF) by comparison with those of enalapril.

METHODS

50 patients with CHF (left ventricular ejection fraction (LVEF) < 40%) were randomly assigned to valsartan (80 mg/day; n = 25) or enalapril (5 mg/day; n = 25). All patients were also treated with a loop diuretic. The delayed heart to mediastinum count (H/M) ratio, delayed total defect score (TDS), and washout rate were determined from (123)I-meta-iodobenzylguanidine (MIBG) images. Plasma BNP concentrations were measured before and after six months of treatment. The left ventricular end diastolic volume (LVEDV) and LVEF were also determined by echocardiography.

RESULTS

In patients receiving valsartan, TDS decreased from a mean (SD) of 43 (8) to 39 (10) (p < 0.01), H/M ratio increased from 1.70 (0.17) to 1.78 (0.22) (p < 0.05), washout rate decreased from 46 (11)% to 41 (10)% (p < 0.05), and plasma BNP concentration decreased from 237 (180) pg/ml to 143 (93) pg/ml (p < 0.05). In addition, LVEDV decreased from 172 (42) ml to 151 (45) ml (p < 0.05) and LVEF increased from 31 (7)% to 39 (10)% (p < 0.001). However, these parameters did not change significantly in patients receiving enalapril.

CONCLUSION

Plasma BNP concentration and (123)I-MIBG scintigraphic and echocardiographic parameters improved significantly after six months of treatment with valsartan. These findings indicate that valsartan can improve cardiac sympathetic nerve activity and left ventricular performance in patients with CHF.

Comparative effects of nicorandil with isosorbide mononitrate on cardiac sympathetic nerve activity and left ventricular function in patients with ischemic cardiomyopathy

BACKGROUND

Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, improves left ventricular (LV) remodeling after myocardial infarction in rat models. However, the effects of chronic nicorandil therapy on cardiac sympathetic nerve activity in patients with ischemic cardiomyopathy have not been determined.

METHODS

Thirty-six patients with ischemic cardiomyopathy (LV ejection fraction [LVEF] < 40%) who underwent successful revascularization procedure before 6 months were treated by standard conventional therapy. Eighteen patients were randomized to additionally receive nicorandil (15 mg/d), whereas the other 18 patients received isosorbide mononitrate (40 mg/d). The delayed heart-to-mediastinum count ratio (H/M ratio), delayed total defect score (TDS), and washout rate (WR) were determined from (123)I-meta-iodobenzylguanidine (MIBG) scintigraphy before and 6 months after treatment. Left ventricular end-diastolic volume (LVEDV) and LVEF were determined by echocardiography.

RESULTS

Total defect score, H/M ratio, WR, LVEDV, and LVEF at baseline were similar for both groups. After treatment, in patients receiving nicorandil, TDS decreased from 50 +/- 6 to 40 +/- 11 (P < .005), H/M ratio increased from 1.68 +/- 0.23 to 1.79 +/- 0.26 (P = .005), and WR decreased from 46% +/- 9% to 40% +/- 12% (P < .005). In addition, LVEDV decreased from 178 +/- 31 to 157 +/- 30 mL (P < .0005), and LVEF increased from 33% +/- 6% to 39% +/- 7% (P < .05). In patients receiving isosorbide mononitrate, no significant changes were observed in these parameters. Moreover, there was a significant correlation between the percent change of LVEF and that of TDS from baseline to 6 months in the patients receiving nicorandil (r = -0.569, P < .05).

CONCLUSIONS

The present study demonstrates improvements in cardiac (123)I-MIBG scintigraphic and echocardiographic parameters with nicorandil treatment. These findings indicate that nicorandil can improve cardiac sympathetic nerve activity and LV function in patients with ischemic cardiomyopathy.