Clinical usefulness of a novel program "Heart Function View" for evaluating cardiac function from gated myocardial perfusion SPECT

Association between an Early Revascularization Strategy and Major Cardiac Events Based on Left Ventricular Dyssynchrony in Patients at Intermediate Risk of Major Cardiac Events Using the J-ACCESS Risk Model

Objective This retrospective study aimed to investigate the association between therapeutic strategies and the development of major cardiac events (MCEs) in intermediate-risk patients by using the the Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (JACCESS) risk model in combination with the stress phase bandwidth (SPBW), an index of left ventricular dyssynchrony. Methods Patients were followed-up for three years to confirm their prognosis. Based on the estimated propensity scores, the patients who underwent revascularization within the first 60 days after SPECT and those who did not were matched 1:1 (n=367 per group). The composite endpoint was the occurrence of MCEs, consisting of cardiac death, non-fatal myocardial infarction, and severe heart failure. SPBW was calculated by a phase analysis using the Heart Risk View-F software program, and the MCE rate was compared between the two groups by applying the normal value of SPBW (38°). Patients The study included 2,053 patients with either known or suspected coronary artery disease who underwent electrocardiogram-gated single-photon emission computed tomography myocardial perfusion imaging and were at intermediate risk of MCE according to the J-ACCESS risk model. Results During follow-up, 54 of the 734 patients (7.4%) experienced MCEs. The overall incidence of MCE in intermediate-risk patients was not significantly different between the two groups. However, the incidence of MCE in patients with an abnormal SPBW was significantly lower in those who underwent early revascularization (4.8% vs. 11.9%, p=0.0407). Conclusion The combination of the J-ACCESS risk model and the SPBW is thus considered to be an optimal treatment strategy for patients at intermediate risk of MCE, and early revascularization may lead to an improved prognosis in intermediate-risk patients with an abnormal SPBW.

Machine Learning for Multi-Vessel Coronary Artery Disease Prediction on Electrocardiogram Gated Single-Photon Emission Computed Tomography

Background: Single-photon emission computed tomography (SPECT) encounters difficulties in diagnosing severe multi-vessel coronary artery disease (svMVD) because of balanced ischemia. We estimated the predictive value of electrocardiogram-gated SPECT for svMVD and improved it using machine learning (ML). Methods and results: We enrolled consecutive 335 patients (median age, 74 years; 255 men) who underwent adenosine stress-gated SPECT (99mTechnesium) and coronary angiography. svMVD was defined as three-vessel disease or left main tract stenosis. Predictive models were constructed using statistical and ML methods. Eighteen cases (5%) showed svMVD, and diabetes, summed stress score (SSS), and the max difference among segmental time of stroke volume per cardiac cycle (MDSV: a parameter of left ventricular [LV] end-systolic dyssynchrony) on adenosine stress were independent significant predictors. The area under the receiver operating characteristic curve (AUC) of SSS and MDSV on stress were 0.759 and 0.763, respectively. Conversely, the extra trees classifier and light gradient boosting machine had improved AUC values of 0.826 and 0.870, respectively, and the MDSV on stress and diabetes showed high feature values in the ML models. Conclusion: ML on SPECT helped to improve the diagnostic performance of svMVD and diabetes, and the parameters of LV dyssynchrony played essential roles in the ML predictive models.

Prognostic risk stratification based on left ventricular mechanical dyssynchrony in patients at low or intermediate risk of major cardiac events using the J-ACCESS risk model

There have been no reports on prognostic prediction and risk stratification based on stress phase bandwidth (SPBW), or a left ventricular (LV) mechanical dyssynchrony index, in patients with known or suspected stable coronary artery disease (CAD) at low or intermediate risk of major cardiac events (MCEs) using the J-ACCESS risk model. We retrospectively investigated 4,996 consecutive patients with known or suspected CAD who underwent rest ²⁰¹Tl and stress ^99mTc-tetrofosmin electrocardiogram (ECG)-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) and followed up for 3 years to confirm their prognosis. MCE risk over 3 years was estimated using an equation based on that used in the J-ACCESS study. The composite endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction (MI), and severe heart failure requiring hospitalization. SPBW was calculated by phase analysis with the Heart Risk View-F software and its normal upper limit was set to 38°. Based on the estimated 3-year incidence of MCEs obtained from the J-ACCESS risk model, 4,123 of the 4,996 consecutive patients were classified as low (n = 2,653) or intermediate risk (n = 1,470) and they were analyzed for follow-up. During the follow-up, 153 patients experienced MCEs: cardiac death (n = 38), non-fatal MI (n = 45), and severe heart failure (n = 70). The results of the multivariate analysis showed age, estimated glomerular filtration rate (eGFR), stress LV ejection fraction, and stress SPBW to be independent predictors of MCEs. The actual 3-year MCE rate in patients at intermediate risk was significantly higher than in those at low risk (6.7% vs. 2.1%, P < 0.0001). However, the actual 3-year MCE rate in patients with abnormal SPBW (> 38°) was 4.0% and 9.2% in low- and intermediate-risk patients, respectively, which corresponded to intermediate and high risk. Kaplan-Meier analysis also showed significant risk stratification by normal SPBW values for both low- and intermediate-risk patients. LV mechanical dyssynchrony assessed with ECG-gated SPECT MPI is useful for risk stratification of known or suspected stable CAD patients at low or intermediate risk of MCEs and may help identify higher risk patients who could not be identified as being at risk based on J-ACCESS risk assessment.

Normal and Range Value Evaluations Using Heart Risk View-Function Based on the Japanese Societyof Nuclear Medicine Working Group Database

Background: Gated myocardial perfusion single-photon emission computed tomography (SPECT) has been used to non-invasively evaluate the left ventricular (LV) volume and function. This study aimed to measure the normal and range values for heart risk view-function (HRV-F) software using the Japanese Society of Nuclear Medicine Working Group (JSNM-WG) normal database and clarify the characteristics of the normal database. Methods:We used 206 myocardial perfusion short-axis images from the normal database. Ejection fraction (EF), end-systolic volume (ESV), end-diastolic volume (EDV), peak filling rate (PFR), 1/3 mean filling rate (MFR), time to PFR (TTPF), and TTPF divided by RR interval (TPFR/RR) were calculated. Phase parameters of 95% histogram bandwidth and standard deviation were also computed using the phase analysis. The relationships among phase parameters, LV volumes, and body surface area (BSA) were evaluated in the age group of ≤65 years. Results: Higher EF was observed in females than in males (p<0.0001). EDV and ESV were significantly higher in males than in females (p<0.0001). Additionally, PFR and 1/3 MFR significantly differed between sexes (p≤0.075). Phase parameters were higher in males than in females, and higher at stress than at rest. All diastolic parameters showed no significant differences between sexes in any age group, whereas differences have remained in phase values. Phase parameters were weakly correlated with EDV (r=0.31), ESV (r=0.43), and BSA (r=0.27), respectively. Conclusions: Mean normal and range values of the normal database were determined using the HRV-F software. The normal and range values can help diagnose gated SPECT data in patients with cardiac diseases.

Prognostic value of left ventricular mechanical dyssynchrony induced by exercise stress in patients with normal myocardial perfusion single-photon emission computed tomography

BACKGROUND

Left ventricular mechanical dyssynchrony (LVMD) induced by exercise stress was reported to be clinically useful in detecting multivessel coronary artery diseases. The aim of this study was to compare the prognostic value of LVMD induced by pharmacological stress with that induced by exercise stress.

METHODS

We retrospectively examined 918 consecutive patients who underwent exercise (N = 310) or pharmacological stress (N = 608) 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) with normal myocardial perfusion. LVMD was evaluated by phase analysis as the indices of phase bandwidth and phase standard deviation (PSD).

RESULTS

During the follow-up period (2.2 ± 1.9 years), 74 major cardiac events (MCEs) occurred (7 cases of cardiac death, 17 cases of heart failure, and 50 cases of coronary intervention). In global patients, the indices of LVMD on rest images were significantly greater in patients with MCEs (bandwidth (°): 51 ± 31 vs 37 ± 21, P = .001, PSD: 14 ± 9 vs 10 ± 6, P = .001). The exercise stress bandwidth was significantly higher in patients with MCEs (62 ± 37° vs 42 ± 21°, P = .026), as was the pharmacological stress bandwidth (57 ± 35° vs 43 ± 24°, P = .006). Multivariate analysis demonstrated the exercise stress bandwidth to be an independent predictor of MCEs (HR 1.017, CI 1.003 to 1.032, P = .019), but the pharmacological stress bandwidth had no influence on MCEs.

CONCLUSIONS

LVMD induced by exercise stress was an independent predictor of MCEs in patients with normal perfusion SPECT, whereas that induced by pharmacological stress had no association with further events.

Prognostic value of the normalization of left ventricular mechanical dyssynchrony after revascularization in patients with coronary artery disease

There are no reports indicating a prognostic difference based on normalization of left ventricular (LV) mechanical dyssynchrony after revascularization in patients with coronary artery disease (CAD). We retrospectively investigated 596 patients who underwent rest ²⁰¹Tl and stress ^99mTc-tetrofosmin electrocardiogram-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging. All patients had significant stenosis with ≥ 75% narrowing of the coronary arterial diameter detected by coronary angiography performed after confirmation of ≥ 5% ischemia by the SPECT. Patients underwent revascularization and thereafter were re-evaluated by the SPECT during a chronic phase, and followed-up to confirm their prognosis for ≥ 1 year. The composite endpoint was the onset of major cardiac events (MCEs) consisting of cardiac death, non-fatal myocardial infarction (MI), unstable angina pectoris (UAP), and severe heart failure requiring hospitalization. The stress phase bandwidth (SPBW) was calculated by phase analysis with the Heart Risk View-F software and its normal upper limit was set to 38°. During the follow-up, 64 patients experienced MCEs: Cardiac death (n = 11), non-fatal MI (n = 5), UAP (n = 26), and severe heart failure (n = 22). The results of the multivariate analysis showed the ∆summed difference score %, ∆stress LV ejection fraction, and stress SPBW after revascularization to be independent predictors of MCEs. Additionally, the results of the multivariate logistic regression analysis showed the summed rest score%, summed difference score%, stress LV ejection fraction, and perfusion defects in the left circumflex artery region before revascularization to be independent predictors for normalized SPBW after revascularization. The prognosis of patients who normalized SPBW after revascularization was similar to that of patients with a normal SPBW before revascularization, while patients who did not normalize after revascularization had the worst prognosis. In conclusion, normalization of LV dyssynchrony after revascularization assessed with nuclear cardiology may help predict future MCEs and thus a useful indicator for predicting improved prognosis in patients with CAD.

Prognostic Significance of Left Ventricular Dyssynchrony Assessed with Nuclear Cardiology for the Prediction of Major Cardiac Events after Revascularization

Objective This retrospective study was aimed at determining whether or not stress phase bandwidth (SPBW), a left ventricular (LV) mechanical dyssynchrony index, predicts major cardiac events (MCEs) and stratifies the risk of those in patients with coronary artery disease (CAD) who undergo revascularization. Methods Patients were followed up to confirm the prognosis for at least one year. The SPBW was calculated by a phase analysis using the Heart Risk View-F software program. The composite endpoint was the onset of MCEs, consisting of cardiac death, non-fatal myocardial infarction, unstable angina pectoris, and severe heart failure requiring hospitalization. Patients The study subjects were 332 patients with CAD who underwent coronary angiography and revascularization after confirming ≥5% ischemia detected by rest ²⁰¹Tl and stress ^99mTc-tetrofosmin electrocardiogram-gated single-photon emission computed tomography myocardial perfusion imaging. Results During the follow-up, 35 patients experienced MCEs of cardiac death (n=5), non-fatal myocardial infarction (n=3), unstable angina pectoris (n=11), and severe heart failure requiring hospitalization (n=16). A receiver operating characteristics analysis indicated that the optimal cut-off value of the SPBW was 52° for predicting MCEs, and the MCE rate was significantly higher in the patients with an SPBW >52° than in those with an SPBW ≤52°. Results of the multivariate analysis showed the SPBW and estimated glomerular filtration rate to be independent predictors for MCEs. In addition, the cut-off value of the SPBW significantly stratified the risk of MCEs according to the results of the Kaplan-Meier analysis. Conclusion Evaluating the SPBW before revascularization may help predict future MCEs in patients with CAD who intended to undergo treatment.

Influences of radionuclides on left ventricular phase analysis of gated myocardial perfusion single-photon emission computed tomography images in ischemic heart disease

OBJECTIVE

Phase analysis is expected to improve the accuracy of myocardial ischemia diagnosis in conjunction with myocardial perfusion and wall motion imaging and quantification. Although previous studies have reported perfusion image disagreements in relation to radionuclides, a few reports have examined the influences of radionuclides on phase analysis. We evaluated the influences of different radionuclides on stress-induced left ventricular mechanical dyssynchrony by phase analysis using electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) (MPS) imaging in patients with ischemic heart disease (IHD).

METHODS

A total of 202 patients with suspected or known IHD were investigated retrospectively. All the patients underwent coronary arteriography and were subsequently classified into the following groups: 43 patients without any coronary lesion (0VD), 71 patients with single-vessel disease (1VD), 59 patients with two-vessel disease (2VD), and 29 patients with three-vessel disease (3VD). Both stress and rest gated-MPS were performed using 99mTc-methoxyisobutylisonitrile (MIBI)/tetrofosmin (TF) in 118 patients and with 201TlCl in 84 patients. Phase analysis was performed to obtain the peak phase, phase standard deviation (SD), and bandwidth. Finally, we investigated potential differences between the phase analysis indices and the respective radionuclides used.

RESULTS

The peak phase did not exhibit any significant differences in the numbers of affected branches in either 99mTc-MPS or 201Tl-MPS during stress or rest MPS. Furthermore, both the phase SD and bandwidth demonstrated a tendency to increase in patients with increased numbers of affected branches. A significant difference was observed in the stress MPS when 99mTc-MIBI/TF was used (p < 0.05), but no significant difference was observed in the stress MPS when 201TlCl was used. Both the phase SD and bandwidth of all patients in 99mTc-MPS during stress were significantly larger than those at rest (p < 0.05). Conversely, both the phase SD and bandwidth of all patients in 201Tl-MPS at stress was significantly smaller than that at rest (p < 0.05).

CONCLUSION

Phase analysis using 99mTc-MPS was considered to be useful for the detection of stress-induced left ventricular mechanical dyssynchrony, although it is necessary to be careful when using 201Tl-MPS.

Prognostic Value of Left Ventricular Dyssynchrony Assessed with Nuclear Cardiology in Patients with Known or Suspected Stable Coronary Artery Disease with Preserved Left Ventricular Ejection Fraction

Left ventricular (LV) mechanical dyssynchrony assessed with phase analysis of electrocardiogram (ECG) -gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is useful for predicting major cardiac events (MCEs) in patients with cardiac dysfunction. However, there is no report on its usefulness in Japanese patients with known or suspected stable coronary artery disease (CAD) with preserved LV ejection fraction (LVEF).We retrospectively investigated 3,374 consecutive patients with known or suspected CAD who underwent rest ²⁰¹Tl and stress ^99mTc-tetrofosmin ECG-gated SPECT MPI and had preserved LVEF (≥ 45%), and followed them up to confirm their prognosis for three years. The composite endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction (MI), unstable angina pectoris, and severe heart failure requiring hospitalization. LV mechanical dyssynchrony was evaluated with phase analysis with the Heart Risk View-F software to obtain the phase bandwidth and standard deviation.During the follow-up, 179 patients experienced MCEs: cardiac death (n = 42); non-fatal MI (n = 34); unstable angina pectoris (n = 54); and severe heart failure (n = 49). Results of the multivariate analysis showed age, a history of MI, diabetes mellitus, summed stress score, and stress phase bandwidth to be independent predictors for MCEs. In Kaplan-Meier analysis, prognoses were significantly stratified with the tertiles of stress phase bandwidth.LV mechanical dyssynchrony assessed with ECG-gated SPECT MPI is useful for predicting a prognosis and stratifying the risk of MCEs in Japanese patients with known or suspected stable CAD with preserved LVEF.

Prognostic value of left ventricular dyssynchrony evaluated by gated myocardial perfusion imaging in patients with chronic kidney disease and normal perfusion defect scores

BACKGROUND

This study aimed to investigate whether indices of left ventricular (LV) dyssynchrony by gated myocardial perfusion SPECT (GMPS) could be useful to predict prognosis in chronic kidney disease (CKD) patients with normal perfusion defect scores.

METHODS

One hundred and sixty-seven CKD patients with normal perfusion defect scores on adenosine-stress 201Tl GMPS and no previous history of overt heart diseases were enrolled. Phase standard deviation (PSD) and bandwidth (BW) were automatically calculated from GMPS. The major adverse cardiac events (MACEs) for a mean of 560 days were defined as sudden cardiac death, fatal arrhythmias, and acute coronary syndrome requiring urgent coronary revascularization. Patients were divided into two groups according to the presence or absence of MACEs.

RESULTS

The MACEs occurred in 12 patients (7.1%). Patients who experienced MACEs showed significantly higher PSD and wider BW than those who did not. In the Kaplan-Meier event-free survival analysis, cardiac event rate was significantly higher in the high-PSD and wide-BW group (n = 81) than in the low-PSD and narrow-BW group (n = 71) (P = .002). The multivariate regression analysis revealed that the PSD was associated with MACEs (odds ratio 1.33, 95% confidence interval 1.05-1.69, P = .01).

CONCLUSION

The LV dyssynchrony indices from GMPS may be novel prognostic predictors in CKD patients with normal perfusion defect scores.

[Assessment of Left Ventricular Diastolic Function Using ECG-gated Myocardial Perfusion SPECT in Small Heart: Comparison with Ultrasound Echocardiography]

BACKGROUND

Assessment of left ventricular (LV) diastolic function is important because it is possible to detect early sign of myocardial ischemia by this assessment. The purpose of this study was to compare between electrocardiogram (ECG) -gated myocardial perfusion single photon emission computed tomography (G-SPECT) and ultrasound echocardiography in assessment of LV diastolic function in the small heart (SH).

METHODS

The study population consisted of 144 patients who underwent both G-SPECT and ultrasound echocardiography. Peak filling rate (PFR), one-third mean filling rate (1/3 MFR) and the ratio of time to PFR to the RR interval (TPFR/RR) were calculated by quantitative gated SPECT (QGS) and heart risk view-F (HRV-F). Peak early mitral annular velocity (e') was used as the reference standard of LV diastolic function.

RESULTS

There were 33 patients with end-systolic volume (ESV) of ≤10 ml (SH10), 51 patients with ESV of 11-20 ml (SH 20) and 60 patients with ESV of >20 ml (normal-sized heart: NH). In SH10, PFR calculated by QGS was not correlated with e'. However, that by HRV-F was significantly correlated with e' (r=0.47, p=0.006). On the other hand, 1/3 MFR and TPFR/RR calculated by QGS and HRV-F were not correlated with e' in SH10 and SH20. PFR, 1/3 MFR and TPFR/RR calculated by QGS and HRV-F were correlated with e' in NH.

Comparison of phase dyssynchrony analysis using gated myocardial perfusion imaging with four software programs: Based on the Japanese Society of Nuclear Medicine working group normal database

PURPOSE

Left ventricular (LV) phase dyssynchrony parameters based on gated myocardial perfusion imaging varied among software programs. The aim of this study was to determine normal ranges and factors affecting phase parameters.

METHODS

Normal databases were derived from the Japanese Society of Nuclear Medicine working group (n = 69). The programs were Emory Cardiac Toolbox with SyncTool (ECTb), Quantitative Gated SPECT (QGS), Heart Function View (HFV), and cardioREPO (cREPO); parameters of phase standard deviation (PSD), 95% bandwidth, and entropy were compared with parameters with ECTb as a reference.

RESULTS

PSD (degree) was 5.3 ± 3.3 for QGS (P < .0001), 5.4 ± 2.5 for HFV (P < .0001), and 10.3 ± 3.2 for cREPO (P = n. s.) compared with 11.5 ± 5.5 for ECTb. Phase bandwidth with three programs differed significantly from ECTb. Gender differences were significant for all programs, indicating larger variation in males. After adjustment of LV volumes between genders, the difference disappeared except for QGS. The phase parameters showed wider variations in patients with the lower ejection fraction (EF) and larger LV volumes, depending on software types.

CONCLUSION

Based on normal ranges of phase dyssynchrony parameters in four software programs, dependency on genders, LV volume, and EF should be considered, indicating the need for careful comparison among different software programs.

Normal values and standardization of parameters in nuclear cardiology: Japanese Society of Nuclear Medicine working group database

As a 2-year project of the Japanese Society of Nuclear Medicine working group activity, normal myocardial imaging databases were accumulated and summarized. Stress-rest with gated and non-gated image sets were accumulated for myocardial perfusion imaging and could be used for perfusion defect scoring and normal left ventricular (LV) function analysis. For single-photon emission computed tomography (SPECT) with multi-focal collimator design, databases of supine and prone positions and computed tomography (CT)-based attenuation correction were created. The CT-based correction provided similar perfusion patterns between genders. In phase analysis of gated myocardial perfusion SPECT, a new approach for analyzing dyssynchrony, normal ranges of parameters for phase bandwidth, standard deviation and entropy were determined in four software programs. Although the results were not interchangeable, dependency on gender, ejection fraction and volumes were common characteristics of these parameters. Standardization of ¹²³I-MIBG sympathetic imaging was performed regarding heart-to-mediastinum ratio (HMR) using a calibration phantom method. The HMRs from any collimator types could be converted to the value with medium-energy comparable collimators. Appropriate quantification based on common normal databases and standard technology could play a pivotal role for clinical practice and researches.