Yasushi Wakabayashi

The clinical impact of late gadolinium enhancement in Takotsubo cardiomyopathy: serial analysis of cardiovascular magnetic resonance images

BackgroundOur study aimed to investigate both the clinical implications of late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR) and the relation of LGE to clinical findings in patients with Takotsubo cardiomyopathy (TTC).MethodsWe evaluated 20 consecutive patients (2 men, 18 women; median age, 77 years; interquartile range [IQR] 67-82 years) who were admitted to our hospital with the diagnosis of TTC. CMR was performed within 1 week after admission, and follow-up studies were conducted 1.5 and 6 months later.ResultsIn 8 patients, CMR imaging during the sub-acute phase revealed LGE in the area matched with wall motion impairment. Cardiogenic shock was more frequently observed in patients with LGE than in those without LGE (38% vs 0%, p = 0.049). The patients with LGE needed a longer duration for ECG normalization and recovery of wall motion than did those without LGE (median 205 days, IQR [152-363] vs 68 days, [43-145], p = 0.005; 15 days, [10-185] vs 7 days, [4-13], p = 0.030, respectively). In 5 of these 8 patients, LGE disappeared within 45-180 days (170, IQR [56-180]) of onset. The patients with LGE remaining in the chronic phase had higher peak creatine kinase levels than did those without LGE (median 307 IU/L, IQR [264-460] vs 202 IU/L, [120-218], p = 0.017).ConclusionLGE by CMR in the sub-acute phase may be associated with the severity and prolonged recovery to normal of clinical findings in TTC.

Prognosis of hypertrophic cardiomyopathy: Assessment by123I-BMIPP (β-methyl-p-(123I)iodophenyI pentadecanoic acid) myocardial single photon emission computed tomography

Abstract123I-BMIPP (β-methyl-iodophenyl pentadecanoic acid) has shown unique properties for potential use in assessing myocardial metabolism. Previous basic and clinical studies demonstrated that the disturbances of myocardial metabolism precede the occurrence of myocardial perfusion abnormalities by using201Tl in hypertrophic myocardium. The present study was therefore undertaken to determine whether or not123I-BMIPP myocardial SPECT is useful in predicting the prognosis of hypertrophic cardiomyopathy (HCM) in 65 patients in 6 facilities. There were 33 patients with non-obstructive HCM, 12 with obstructive HCM, 12 with apical HCM and 8 with dilated-phase HCM. Fasted patients at rest received an intravenous injection of 111 MBq of123I-BMIPP. Twenty to thirty minutes later, myocardial SPECT was carried out. The BMIPP severity score (BMIPP SS) was evaluated semiquantitatively by using representative short axial SPECT images. We followed up the incidence of cardiac events for a mean period of 3.0 ± 0.6 years. Cardiac events occurred in 13 patients. Of these, 11 developed heart failure and 6 died (4 from heart failure and 2 from sudden death). The BMIPP SS in the dilated-phase HCM was significantly higher than that in the remaining HCM patients. The BMIPP SS for the survivors was significantly lower than that for the non-survivors. The BMIPP SS was particularly high in patients with fatal heart failure. Furthermore, there was a close negative correlation between the BMIPP SS and percent fractional shortening measured by echocardiography (r = −0.49). Finally, the mortality over the three years increased according to the extent of the BMIPP SS. In conclusion, these results indicate that the BMIPP SS is useful in evaluating the severity of HCM. We conclude that123I-BMIPP is a valuable metabolic tracer in predicting the outcome of HCM.

Distribution of late gadolinium enhancement in end-stage hypertrophic cardiomyopathy and dilated cardiomyopathy: differential diagnosis and prediction of cardiac outcome.

BACKGROUND The prognostic implications of late gadolinium enhancement (LGE) have been evaluated in ischemic and non-ischemic cardiomyopathies. The present study analyzed LGE distribution in patients with end-stage hypertrophic cardiomyopathy (ES-HCM) and with dilated cardiomyopathy (DCM), and tried to identify high risk patients in DCM. METHODS Eleven patients with ES-HCM and 72 with DCM underwent cine- and LGE-cardiac magnetic resonance and ultrasound cardiography. The patient outcome was analyzed retrospectively for 5years of follow-up. RESULTS LGE distributed mainly in the inter-ventricular septum, but spread more diffusely into other left ventricular segments in patients with ES-HCM and in a certain part of patients with DCM. Thus, patients with DCM can be divided into three groups according to LGE distribution; no LGE (n=24), localized LGE (localized at septum, n=36), and extensive LGE (spread into other segments, n=12). Reverse remodeling occurred after treatment in patients with no LGE and with localized LGE, but did not in patients with extensive LGE and with ES-HCM. The event-free survival rate for composite outcome (cardiac death, hospitalization for decompensated heart failure or ventricular arrhythmias) was lowest in patients with extensive LGE (92%, 74% and 42% in no LGE, localized LGE, and extensive LGE, p=0.02 vs. no LGE), and was comparable to that in patients with ES-HCM (42%). CONCLUSIONS In DCM, patients with extensive LGE showed no functional recovery and the lowest event-free survival rate that were comparable to patients with ES-HCM. The analysis of LGE distribution may be valuable to predict reverse remodeling and to identify high-risk patients.

Comparison of [123I]metaiodobenzylguanidine kinetics with heart rate variability and plasma norepinephrine level

Background[123I]Metaiodobenzylguanidine (MIBG) imaging has been used to assess cardiac sympathetic nerve abnormalities. We evaluated the clinical significance of myocardial MIBG imaging as a measure of cardiac sympathetic nervous system function by comparing it to heart rate variability and plasma norepinephrine level.Methods and ResultsIn 211 subjects, we analyzed heart rate variability with 24-hour electrocardiography, performed scintigraphy with MIBG, and measured plasma norepinephrine levels. Time and frequency domain measures of heart rate variability were calculated with the Marquette heart rate variability program (Marquette Electronics, Milwaukee, Wis.). Early and late myocardial MIBG uptakes were measured at 15 and 150 minutes after injection, respectively. MIBG clearance rate from the heart and heart-to-lung and heart-to-mediastinum ratios of MIBG activities were calculated. On the whole, heart rate variability, including low-frequency power, correlated positively, but modestly so, with late MIBG uptake and negatively with MIBG clearance rate. The plasma norepinephrine level correlated negatively with late MIBG uptake and with heart rate variability, including low-frequency power, and positively with MIBG clearance rate. Similar correlations were also observed in patient subgroups with coronary artery disease, diabetes mellitus, and renal failure, but these correlations were weak (R2<0.5).ConclusionsIncreased cardiac sympathetic nervous system activity may be associated with increased myocardial MIBG clearance and decreased heart rate variability, including low-frequency power. Because these associations were not strong, however, the combination of heart rate variability with MIBG may allow an interactive assessment of the cardiac autonomic nervous system.

Evaluation of right and left ventricular function by quantitative blood-pool SPECT (QBS): Comparison with conventional methods and quantitative gated SPECT (QGS)

Though quantitative ECG-gated blood-pool SPECT (QBS) has become a popular tool in research settings, more verification is necessary for its utilization in clinical medicine. To evaluate the reliability of the measurements of left and right ventricular functions with QBS, we performed QBS, as well as first-pass pool (FPP) and ECG-gated blood-pool (GBP) studies on planar images in 41 patients and 8 healthy volunteers. Quantitative ECG-gated myocardial perfusion SPECT (QGS) was also performed in 30 of 49 subjects. First, we assessed the reproducibility of the measurements of left and right ventricular ejection fraction (LVEF, RVEF) and left and right ventricular end-diastolic volume (LVEDV, RVEDV) with QBS. Second, LVEF and RVEF obtained from QBS were compared with those from FPP and GBP, respectively. Third, LVEF and LVEDV obtained from QBS were compared with those from QGS, respectively. The intra- and inter-observer reproducibilities were excellent for LVEF, LVEDV, RVEF and RVEDV measured with QBS (r = 0.88 to 0.96, p < 0.01), while the biases in the measurements of RVEF and RVEDV were relatively large. LVEF obtained from QBS correlated significantly with those from FPP and GBP, while RVEF from QBS did not. LVEF and LVEDV obtained from QBS were significantly correlated with those from QGS, but the regression lines were not close to the lines of identity. In conclusion, the measurements of LVEF and LVEDV with QBS have good reproducibility and are useful clinically, while those of RVEF and RVEDV are less useful compared with LVEF and LVEDV. The algorithm of QBS for the measurements of RVEF and RVEDV remains to be improved.

Quantification of left ventricular size on exercise thallium-201 single-photon emission tomography

The purposes of this study were to determine whether quantification of the left ventricular size on exercise thallium-201 single-photon emission tomography (SPET) correlates with echocardiographic measurements, whether the quantification reflects the severity of coronary artery disease, and whether it can provide supplementary information regarding the severity of coronary artery disease. In 42 control subjects and 110 patients who underwent coronary angiography, we performed exercise201Tl SPET and quantified six non-regional markers: lung201Tl uptake on an initial planar image (Lung/Heart), left ventricular width on a tomogram (Width), change in the Width from the initial to delayed tomograms (ΔWidth), count ratio of the left ventricular cavity to the myocardium (C/M), count ratio of the lung to the myocardium (UM), and count ratio of the lung to the left ventricular cavity (L/C). In 76 patients, furthermore, the Width was compared with echocardiographic measurements. The Width correlated with echocardiographic measurements (P<0.001). The Width and ΔWidth were significantly different among zero-, one-, two- and three-vessel disease (P<0.001). However, the Width and ΔWidth could not improve the power of discrimination for multi-vessel disease derived from the Lung/Heart. The six non-regional markers correlated with each other (P<0.001). Among the six markers, the Lung/Heart was only the independent discriminator for multi-vessel disease. In conclusion, quantification of the left ventricular size on exercise201Tl SPET correlated with echocardiographic measurements and reflected the severity of coronary artery disease, but may be replaced with quantitation of the lung201Tl uptake.

Functional, morphological and electrocardiographical abnormalities in patients with apical hypertrophic cardiomyopathy and apical aneurysm: correlation with cardiac MR.

Objective The prognosis of apical hypertrophic cardiomyopathy (APH) has been benign, but apical myocardial injury has prognostic importance. We studied functional, morphological and electrocardiographical abnormalities in patients with APH and with apical aneurysm and sought to find parameters that relate to apical myocardial injury. Methods Study design: a multicentre trans-sectional study. Patients: 45 patients with APH and 5 with apical aneurysm diagnosed with transthoracic echocardiography (TTE) in the database of Hamamatsu Circulation Forum. Measure: the apical contraction with cine-cardiac MR (CMR), the myocardial fibrotic scar with late gadolinium enhancement (LGE)-CMR, and QRS fragmentation (fQRS) defined when two ECG-leads exhibited RSR’s patterns. Results Cine-CMR revealed 27 patients with normal, 12 with hypokinetic and 11 with dyskinetic apical contraction. TTE misdiagnosed 11 (48%) patients with hypokinetic and dyskinetic contraction as those with normal contraction. Apical LGE was apparent in 10 (83%) and 11 (100%) patients with hypokinetic and dyskinetic contraction, whereas only in 11 patients (41%) with normal contraction (p<0.01). Patients with dyskinetic apical contraction had the lowest left ventricular ejection fraction, the highest prevalence of ventricular tachycardia, and the smallest ST depression and depth of negative T waves. The presence of fQRS was associated with impaired apical contraction and apical LGE (OR=8.32 and 8.61, p<0.05). Conclusions CMR is superior to TTE for analysing abnormalities of the apex in patients with APH and with apical aneurysm. The presence of fQRS can be a promising parameter for the early detection of apical myocardial injury.

Usefulness of measurement of plasma atrial natriuretic peptide levels in exercise testing of patients with coronary heart disease

Atrial natriuretic peptide secretion on exercise testing may be exaggerated by left ventricular dysfunction due to multivessel coronary disease rather than by scintigraphically detectable myocardial ischemia. The measurement of plasma atrial natriuretic peptide levels during exercise test may provide additional information regarding the severity of coronary heart disease.