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Corresponding author at: Department of Cardiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-Ku, Tokyo 173-8610, Japan. Tel.: +81 3 3972 8111; fax: +81 3 3972 1098.
A Heart Risk Table has been reported as the first risk score based on nuclear cardiology to predict cardiac event rates in Japanese patients. However, there are no risk scores estimating risk of major cardiac events (MCEs) except severe heart failure.
Methods
We retrospectively investigated 2579 patients with known or suspected coronary artery disease (CAD) who underwent rest 201Tl and stress 99mTc-tetrofosmin myocardial perfusion single photon emission computed tomography between October 2004 and March 2011 and who had data on a 3-year follow-up. The perfusion images were analyzed with 20 segments of a five-point visual scoring model to estimate summed defect scores. The endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction and unstable angina pectoris.
Results
During the 3-year follow-up, 171 patients (6.6%) experienced MCEs comprising cardiac death (n = 78), non-fatal myocardial infarction (n = 30), and unstable angina pectoris (n = 63). The multivariate logistic regression analysis indicated age, diabetes, estimated glomerular filtration rate (eGFR), and summed stress scores (SSS) as independent predictors of the MCEs and age, stress ejection fraction, eGFR, and SSS as independent predictors of cardiac death. Those four predictors and coefficients corresponding to them were used to make two different risk equations: MCE risk (%/3 years) = 1/{1 + Exp[−(−3.176 + 0.018 × age + 0.602 × diabetes − 0.022 × eGFR + 0.051 × SSS)]} × 100 and cardiac death risk (%/3 years) = 1/{1 + Exp[−(−2.602 + 0.031 × age − 0.031 × eGFR + 0.038 × SSS − 0.029 × stress ejection fraction)]} × 100.
Conclusion
The risk scores obtained from this study are useful to predict MCEs in Japanese patients with CAD and are expected to be useful for management and informed consent of high-risk CAD patients.
Prediction of cardiac event risk is important for determination of an optimal treatment strategy in patients with coronary artery disease (CAD). A prediction algorithm developed in an epidemiological study in the USA [
] predicts the risk of CAD over 10 years in a Caucasian population on the basis of categorical data on sex, age, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, blood pressure, diabetes mellitus (DM), and smoking. This algorithm is a highly recommended tool to predict risk of cardiac events in the Guideline on the Assessment of Cardiovascular Risk published by American College of Cardiology and American Heart Association in 2013 [
2013 ACC/AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
Myocardial perfusion single photon emission computed tomography (SPECT) has been well recognized as a useful imaging methodology for prediction of future cardiac events in patients with known or suspected CAD since the reports of Hachamovitch et al. [
Incremental prognostic value of myocardial perfusion single photon emission computed tomography for the prediction of cardiac death: differential stratification for risk of cardiac death and myocardial infarction.
Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography.
]. Also, in Japan, myocardial perfusion SPECT has commonly been used to predict cardiac events in patients with CAD. Risk stratification of cardiac events by nuclear cardiology has been demonstrated in some large-scale prognostic studies including the multicenter prospective Japanese Assessment of Cardiac Events and Survival Study in patients with ischemic heart disease (J-ACCESS) [
Cardiovascular events in Japanese asymptomatic patients with type 2 diabetes: a 1-year interim report of a J-ACCESS 2 investigation using myocardial perfusion imaging.
Myocardial perfusion imaging for predicting cardiac events in Japanese patients with advanced chronic kidney disease: 1-year interim report of the J-ACCESS 3 investigation.
Prognostic value of myocardial perfusion single-photon emission computed tomography for the prediction of future cardiac events in a Japanese population – a middle-term follow-up study.
Cardiac event risk in Japanese subjects estimated using gated myocardial perfusion imaging, in conjunction with diabetes mellitus and chronic kidney disease.
] estimated risk of major cardiac events (MCEs) in Japanese patients with CAD using five independent predictors: age, presence of DM, rested left ventricular ejection fraction (LVEF), summed stress scores (SSS), and estimated glomerular filtration rate (eGFR) obtained from the J-ACCESS database (n = 2395). They prepared an equation consisting of the five independent predictors and coefficients corresponding to those to estimate MCEs within 3 years, and published a Heart Risk Table.
Although this table indicates the first risk score based on nuclear cardiology to predict MCE rates in Japanese patients with CAD, more than half of the MCEs observed are related to severe heart failure. In general, MCEs defined in studies outside Japan [
Incremental prognostic value of myocardial perfusion single photon emission computed tomography for the prediction of cardiac death: differential stratification for risk of cardiac death and myocardial infarction.
Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography.
] included no severe heart failure requiring hospitalization unlike those defined in the J-ACCESS.
We, therefore, have conducted a single-center large-scale retrospective prognostic study in Japanese patients with CAD undergoing nuclear cardiology to prepare a formulation providing risk scores of MCEs excluding severe heart failure during 3 years.
Materials and methods
The institutional review board of Nihon University Itabashi Hospital approved this study, which proceeded in accordance with the ethical standards established in the 1964 Declaration of Helsinki. All study participants provided written informed consent prior to inclusion in this study.
Patient population
We retrospectively investigated 2579 patients with known or suspected CAD who underwent rest 201Tl and stress 99mTc-tetrofosmin myocardial perfusion SPECT [
Prognostic value of myocardial perfusion single-photon emission computed tomography for the prediction of future cardiac events in a Japanese population – a middle-term follow-up study.
Incremental value of regional wall motion analysis immediately after exercise for the detection of single-vessel coronary artery disease – study by separate acquisition, dual-isotope ECG-gated single-photon emission computed tomography.
Diagnostic value of automated quantification of nuclear cardiology in Japanese patients with single vessel coronary artery disease: comparison between Japanese and American normal databases.
Usefulness of automated assessment of nuclear cardiology for prediction of major cardiac events in Japanese patients with known or suspected coronary artery disease: comparison with conventional visual assessment in a large-scale prognostic study.
] at Nihon University Itabashi Hospital between October 2004 and March 2011 and who had data on a 3-year follow-up. We excluded patients aged ≤20 years, those with hypertrophic or dilated cardiomyopathy, those with serious valvular heart disease, those with heart failure being class III or higher New York Heart Association (NYHA) functional classification, those undergoing revascularization within 90 days after the SPECT, and those having no baseline eGFR data.
Follow-up examinations were based on medical records for patients who periodically attended the hospital and responded to a posted questionnaire for patients who had no periodical visits.
The procedure of rest 201Tl and stress 99mTc-tetrofosmin electrocardiogram (ECG)-gated myocardial perfusion SPECT was performed according to a protocol previously reported [
Prognostic value of myocardial perfusion single-photon emission computed tomography for the prediction of future cardiac events in a Japanese population – a middle-term follow-up study.
Incremental value of regional wall motion analysis immediately after exercise for the detection of single-vessel coronary artery disease – study by separate acquisition, dual-isotope ECG-gated single-photon emission computed tomography.
Diagnostic value of automated quantification of nuclear cardiology in Japanese patients with single vessel coronary artery disease: comparison between Japanese and American normal databases.
Usefulness of automated assessment of nuclear cardiology for prediction of major cardiac events in Japanese patients with known or suspected coronary artery disease: comparison with conventional visual assessment in a large-scale prognostic study.
]. All patients received an intravenous (i.v.) injection of 201Tl (111 MBq) and a sixteen-frame-gated SPECT image was initiated 10 min after injection during rest. Then an i.v. injection of 99mTc-tetrofosmin (740 MBq) was performed under stress induced by ergometer exercise in 27% of the patients or by adenosine triphosphate in 73% of those. Sixteen-frame-gated SPECT image acquisition was initiated 30 min after the exercise or 30–60 min after the adenosine triphosphate stress. The acquisition was performed in a supine position and subsequently in a prone position. No attenuation or scatter correction was used. Twelve-lead ECG was monitored continuously during stress tests. Heart rate and blood pressure were recorded at baseline and every minute for at least 3 min after the stress.
The projection data over 360° were obtained with 64 × 64 matrices and a circular orbit. A triple-detector SPECT system equipped with low-energy high-resolution collimators was used (Toshiba, GCA9300A, Tokyo, Japan). SPECT images were reconstructed from the data with a data processor (Philips North America, JETStream Workspace 3.0, Andover, MA, USA) combined with a Butterworth filter of 201Tl (order 5; cut-off frequency 0.42 cycles/cm), that of 99mTc (order 5; cut-off frequency 0.44 cycles/cm) and a ramp filter.
] on three short-axis (distal, mid, basal) and one vertical long-axis (mid) slices, and the tracer uptake of each segment was visually scored using a five-point scale (0: normal; 1: slight reduction of uptake; 2: moderate reduction of uptake; 3: severe reduction of uptake; and 4: absence of uptake). The sum total of the scores of 20 segments in the stress and rest images provided the SSS and the summed rest score (SRS), respectively. The summed difference score (SDS) was calculated as the difference between the SSS and SRS. Cohen's kappa (κ), which was calculated to determine the inter-observer variability for the summed defect score, was 0.92, indicating very good reproducibility.
Sixteen-frame quantitative-gated SPECT data were analyzed using QGS™ software (Cedars-Sinai Medical Center, Los Angeles, CA, USA) to calculate LVEF (%), end-diastolic volume (LVEDV, mL), and end-systolic volume (LVESV, mL) as described by Germano et al. [
The GFR was calculated from serum creatinine levels at the time of SPECT for each patient in the final prognostic analysis population using the Modification of Diet in Renal Disease Equation for Japanese Patients proposed by the Japanese Society of Nephrology [
where A is 1 for men and 0.739 for women and eGFR is expressed as mL/min/1.73 m2. Patients having eGFR < 60 mL/min/1.73 m2 were diagnosed as having CKD.
Patient follow-up
All patients were followed up for 3 years (36.2 ± 9.7 months) after the initial stress myocardial perfusion-gated SPECT. The study endpoint was the onset of MCEs within the 3-year follow-up, consisting of cardiac death, non-fatal myocardial infarction (MI), and unstable angina pectoris (UAP) identified from medical records or from responses to a posted questionnaire. When a patient had several cardiac events, only the first event was taken as the follow-up endpoint.
Statistical analysis
Continuous variables were calculated as means and standard deviations. Intergroup comparisons of continuous variables were achieved using an unpaired t test. Intergroup comparisons of categorical variables and global chi-square values were achieved using the chi-square test. Univariate analyses proceeded using a Cox proportional hazards model. Multivariate analyses proceeded using a stepwise Cox proportional hazards model. Multivariate logistic regression analysis was used to derive equations. All data were analyzed using MedCalc Software Version 13.1.2.0 (Mariakerke, Belgium). A p-value of <0.05 was considered statistically significant.
Results
Major cardiac event rates and patient characteristics
During the 3-year follow-up, 171 (6.6%) of 2579 patients experienced MCEs including cardiac death (n = 78), non-fatal MI (n = 30), and UAP (n = 63). The cardiac deaths comprised 24 cases with fatal MI, 22 cases with sudden arrhythmic death, and 32 cases with congestive heart failure. Table 1 summarizes the characteristics of the patients with and without MCEs. The proportions of patients with a typical chest pain, those with a history of MI or revascularization, and those with hypertension or DM were significantly higher in the group with MCEs than without MCEs (p < 0.004). The proportion of patients having hyperlipidemia or smoking habit was similar between the two groups. The proportion of patients treated with aspirin, β-blockers, or nitrates was significantly higher in the group with MCEs than without MCEs (p < 0.003). The proportion of patients treated with other medications including statins, calcium antagonists, angiotensin II receptor blockers, or angiotensin-converting enzyme inhibitors was similar between the two groups with and without MCEs. Myocardial defect scores (SSS, SRS, and SDS) as well as LVEDV and LVESV among QGS parameters in both rest and stress images were significantly higher in the group with MCEs than without MCEs (p < 0.0001). In contrast, LVEF in both rest and stress images and eGFRs were significantly lower in the group with MCEs than without MCEs (p < 0.0001).
Table 1Characteristics of patients with and without major cardiac events.
The patients were classified according to SSS grades of normal (n = 1733), mildly (n = 312), moderately (n = 173), and severely (n = 361) abnormal. Fig. 1 shows cardiac death and MCE rates during the 3-year follow-up in each SSS grade group. The cardiac death rates during 3 years were 1.5%, 2.9%, 3.5%, and 10.2% for normal, mildly, moderately, and severely abnormal groups, respectively. The cardiac death rate was significantly higher in the severely abnormal group than in the normal (p < 0.0001) and mildly (p = 0.0010) and moderately (p = 0.0243) abnormal groups.
Fig. 1Rates of cardiac death (open column) and MCE (solid column) during 3 years stratified with SSS. *Statistical significance vs. normal; **statistical significance vs. normal, mild and moderate abnormal; ***statistical significance between MCEs and cardiac death rates in normal, mild, moderate and severe abnormal. MCEs, major cardiac events; SSS, summed stress scores.
The MCE rates during 3 years were 3.7%, 8.0%, 12.1%, and 16.6% for normal, mildly, moderately and severely abnormal groups, respectively, being directly proportional to SSS severity. The MCE rate was significantly higher in the mildly (p = 0.0012), moderately (p < 0.0001), and severely (p < 0.0001) abnormal groups than in the normal group. Statistically significant difference in the MCE rates also was observed between mildly and severely abnormal groups (p = 0.0012).
The MCE rates were significantly higher than the cardiac death rates in all groups (p < 0.0001 for normal group; p = 0.0082 for mildly, p = 0.0050 for moderately, and p = 0.0164 for severely abnormal groups).
Prediction of MCEs
The results of the univariate Cox proportional hazards regression model analysis showed all demographic and baseline variables except smoking habit to be significant predictors for MCEs. From those variables, age, DM, SSS, and eGFR were extracted as independent predictors for MCEs in multivariate Cox proportional hazards regression model analysis (Table 2).
Table 2Univariate and multivariate Cox proportional hazards regression analysis for risk of MCE.
Table 3 summarizes the results of the univariate and multivariate Cox proportional hazards regression analyses to evaluate a predictor for cardiac death. All demographic and baseline variables except history of revascularization, hypertension, and smoking habit were significant predictors for cardiac death in the univariate analysis. The results of the multivariate analysis indicated age, SSS, stress LVEF, and eGFR to be independent predictors for cardiac death.
Table 3Univariate and multivariate Cox proportional hazards regression analysis for risk of cardiac death.
Fig. 2 shows changes in global chi-square values for prediction of MCEs (a) and cardiac death (b) with combination of the independent predictors identified by the multivariate analysis. The global chi-square values for MCE prediction were 11.4 for age, 43.4 for age + DM, 89.9 for age + DM + CKD, and 138.9 for age + DM + CKD + SSS. The global chi-square values for cardiac death prediction were 10.5 for age, 68.9 for age + CKD, 114.2 for age + CKD + SSS, and 127.1 for age + CKD + SSS + low EF. Both the global chi-square values significantly increased with the incremental number of independent predictors combined.
Fig. 2Changes in global chi-square values for prediction of major cardiac events (a) and cardiac death (b) with combination of the independent predictors identified by the multivariate analysis. DM, diabetes mellitus; CKD, chronic kidney disease; SSS, summed stress scores; EF, ejection fraction.
Multivariate logistic regression analysis and original cardiac event risk score
Table 4 summarizes the results of the multivariate logistic regression analysis for risk of cardiac events in MCE and cardiac death predicting models. Age, SSS, and eGFR were significant variables in both models. In addition to those, DM and stress LVEF were significant variables in the MCE and cardiac death predicting models, respectively.
Table 4Multivariate logistic regression analysis for risk of cardiac events.
On the basis of the four predictors and coefficients corresponding to them, the MCE risk per 3 years was calculated as follows:
Likewise, the cardiac death risk per 3 years was calculated as follows:
where age is given as years, DM is 1 for presence or 0 for absence, eGFR as mL/min/1.73 m2, SSS as continuous variables, and EF as %.
Discussion
This is the first report demonstrating an original risk score for prediction of MCEs except severe heart failure, which was prepared on the basis of the results from the retrospective large-scale cohort study in Japanese patients with known or suspected CAD. With respect to risk scores predicting prognosis in Japanese patients with CAD, the Heart Risk Table based on the J-ACCESS database has been reported to be useful to predict risk of MCEs including severe heart failure within 3 years [
Cardiac event risk in Japanese subjects estimated using gated myocardial perfusion imaging, in conjunction with diabetes mellitus and chronic kidney disease.
However, severe heart failure is generally excluded from MCEs in prognostic studies in Europe and the USA because the criteria for hospitalization of patients with severe heart failure are varied among medical institutes unlike for patients with acute coronary syndrome. Therefore, the equations derived from the results of the present study are considered to be useful to estimate risk of MCEs except severe heart failure in Japanese patients with CAD.
In the present study, the results from multivariate analysis indicated that the independent predictors for risk of MCEs were not same as those for risk of cardiac death. Although the common predictors between MCEs and cardiac death were age, eGFR, and SSS, risk of MCEs increased in the presence of DM while risk of cardiac death did in the reduction of stress LVEF. It is easily understood that risk of MCEs resulting from acute coronary syndrome increased in patients having concurrent DM and risk of cardiac death did in patients having left ventricular dysfunction. Combination of the four predictors each led to a significant rise of global chi-square values resulting in improvement of predictive precision for MCEs or cardiac death. On the basis of these results, we have created two different equations using the four independent parameters to precisely predict risk of cardiac death or MCEs except severe heart failure during 3 years.
Risk of cardiac death and MCEs within 3 years was significantly higher in this study than in J-ACCESS [
] (3.0% vs. 1.1%, p < 0.0001 and 6.6% vs. 2.0%, p < 0.0001, respectively). In addition, risk of the MCEs in the normal group with SSS ≤3 was significantly higher in this study than in J-ACCESS (3.7% vs. 1.4%, p < 0.0001). The patients enrolled in this study are considered to be a high-risk population in comparison with those in J-ACCESS. Because retrospective data collected in a core university hospital are likely to include most of those obtained from high-risk patients, these differences may result from selection bias. The severity of CAD in patients enrolled in J-ACCESS was relatively low because of the inter-site variation of inclusion criteria for the pre-test likelihood and severity of CAD. Cardiac event rates reported in J-ACCESS were a half for MCEs and a quarter for cardiac death in comparison with those reported in studies in the USA [
Incremental prognostic value of myocardial perfusion single photon emission computed tomography for the prediction of cardiac death: differential stratification for risk of cardiac death and myocardial infarction.
Cardiac event risk in Japanese subjects estimated using gated myocardial perfusion imaging, in conjunction with diabetes mellitus and chronic kidney disease.
] created using the J-ACCESS database is based on similar parameters such as DM, eGFR, and LVEF to those in our study. An odds ratio for DM was also similar between the Heart Risk Table and the result from our predictive equation; risk of MCEs increased by 2.2-fold and 1.8-fold, respectively, due to concurrent DM. However, MCEs defined in J-ACCESS consisted of cardiac death, non-fatal MI, and severe heart failure and the proportion of severe heart failure was 55.2% (64/116). Therefore, the Heart Risk Table is a suitable model to predict risk of severe heart failure but might be inapplicable for prediction of risk of acute coronary syndrome.
In addition, the Heart Risk Table is limited to prediction of risk of total events and is unable to predict separately risk of MCEs and cardiac death because the total number of MCEs was small. Furthermore, the Heart Risk Table has an issue of the absence of the detailed data on severity obtained from nuclear cardiology, because QGS data were obtained only at rest not at stress and SSS was handled as a nonparametric variable of high or low but not as a continuous variable. In Japan, there is another risk model and calculator (Japan Score), which was created in 2008 on the basis of Japan Cardiovascular Surgery Database accumulated from 2000 [
Japan Cardiovascular Surgery Database Organization Risk model of thoracic aortic surgery in 4707 cases from a nationwide single-race population through a web-based data entry system: the first report of 30-day and 30-day operative outcome risk models for thoracic aortic surgery.
]. The Japan Score is useful to predict risk of early death after cardiac surgery, but is not able to be applied to risk estimation of future MCEs after treatment in Japanese patients with CAD.
In the USA, Hachamovitch et al. created a prognostic adenosine score on the basis of the data obtained from adenosine stress SPECT performed in more than 2000 patients [
]. This score is useful to predict cardiovascular mortality and treatment benefit within 2 years on the basis of 10 variables including age, % myocardium ischemia, DM, and rest and peak heart rates. This was the first risk score based on variables obtained from nuclear cardiology but has never been widespread because it is complicated for use in clinical practice. On the other hand, a risk score obtained from the Framingham Heart Study [
] is well known as a risk score in CAD patients and is able to estimate risk of CAD within 10 years on the basis of data on sex, age, LDL-C, HDL-C, blood pressure, DM, and smoking habit. This risk score has been highly recommended by 2013 ACC/AHA Guideline on the Assessment of Cardiovascular Risk [
2013 ACC/AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
]. There are also risk factors derived from atherosclerosis imaging, including ankle-brachial index, coronary artery calcium, and carotid intima-media thickness, but predictive significance of those factors has not been yet clarified even in the results from a meta-analysis study [
U.S. Preventive Services Task Force Using nontraditional risk factors in coronary heart disease risk assessment: U.S. Preventive Services Task Force recommendation statement.
In Europe, there is a famous risk score for cardiac disease (Euro Score), which is useful to predict risk of death within 30 days after cardiac surgery and is widely used to estimate an early death rate after coronary artery bypass grafting [
Establishment of tools predicting exact risk of future serious events is essential for today's medical practices in the world. Our risk score obtained from the present study is able to predict risk of MCEs before decision to perform percutaneous coronary intervention and/or effective therapies and may be applied to estimation of a risk reduction after the intervention and/or therapies. However, before the application, a future study should be designed to validate the prognostic accuracy of the risk score.
Limitations of this study
The limitation of this study is that our risk score, which was created on the basis of data from a retrospective single-center investigation, may involve selection bias. However, our risk score is able to predict risk of MCEs except severe heart failure and is able to be applied to high-risk patients with CAD unlike the Heart Risk Table currently available in Japan. In addition, this risk score is a tool that is easily used in any other institutes because it is easily calculated with general spreadsheet software.
Also, radiation exposure from cardiac imaging has become a recent important topic. The radiation exposure to the patients from the 201Tl + 99mTc-tetrofosmin dual-isotope SPECT in this study was nearly 30 mSv, which was higher than that from 99mTc-tetrofosmin rest-stress SPECT (8.6 mSv) [
]. However, the reasons why we used this protocol were that patients were not restricted for a long time because of the short procedural length and that the results of the imaging were informed to the patient immediately after the procedure completion. Our risk score is expected to be possibly applied to the 99mTc-tetrofosmin rest-stress SPECT protocol because prediction of prognosis or diagnostic accuracy with 201TI is generally similar to that with 99mTc-tetrofosmin [
ACC/AHA/ACP-ASIM guidelines for the management of patients with chronic stable angina: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Chronic Stable Angina).
In conclusion, the risk scores obtained from this study are useful to predict MCEs in Japanese patients with known or suspected CAD and are expected to be useful for management and informed consent of high-risk patients with CAD whom we meet in daily clinical practice.
Funding
This research received no grant from any funding agency in the public, commercial, or not-for-profit sectors.
Conflict of interest
All authors declare that they have no conflict of interest.
Acknowledgments
We appreciate Miss Yukiko Inoue for assisting with the collection and analyses of data from the posted questionnaires.
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Prediction of coronary heart disease using risk factor categories.
2013 ACC/AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
Incremental prognostic value of myocardial perfusion single photon emission computed tomography for the prediction of cardiac death: differential stratification for risk of cardiac death and myocardial infarction.
Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography.
Cardiovascular events in Japanese asymptomatic patients with type 2 diabetes: a 1-year interim report of a J-ACCESS 2 investigation using myocardial perfusion imaging.
Myocardial perfusion imaging for predicting cardiac events in Japanese patients with advanced chronic kidney disease: 1-year interim report of the J-ACCESS 3 investigation.
Prognostic value of myocardial perfusion single-photon emission computed tomography for the prediction of future cardiac events in a Japanese population – a middle-term follow-up study.
Cardiac event risk in Japanese subjects estimated using gated myocardial perfusion imaging, in conjunction with diabetes mellitus and chronic kidney disease.
Incremental value of regional wall motion analysis immediately after exercise for the detection of single-vessel coronary artery disease – study by separate acquisition, dual-isotope ECG-gated single-photon emission computed tomography.
Diagnostic value of automated quantification of nuclear cardiology in Japanese patients with single vessel coronary artery disease: comparison between Japanese and American normal databases.
Usefulness of automated assessment of nuclear cardiology for prediction of major cardiac events in Japanese patients with known or suspected coronary artery disease: comparison with conventional visual assessment in a large-scale prognostic study.
Japan Cardiovascular Surgery Database Organization
Risk model of thoracic aortic surgery in 4707 cases from a nationwide single-race population through a web-based data entry system: the first report of 30-day and 30-day operative outcome risk models for thoracic aortic surgery.
ACC/AHA/ACP-ASIM guidelines for the management of patients with chronic stable angina: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Chronic Stable Angina).
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