Myocardial perfusion imaging and risk classification for coronary heart disease in diabetic patients. The IDIS study: a prospective, multicentre trial

Comparative effectiveness of positron emission tomography and single-photon emission computed tomography myocardial perfusion imaging for predicting risk in patients with cardiometabolic disease

BACKGROUND

The epidemiology of coronary artery disease (CAD) has shifted, with increasing prevalence of cardiometabolic disease and decreasing findings of obstructive CAD on myocardial perfusion imaging (MPI). Coronary microvascular dysfunction (CMD), defined as impaired myocardial flow reserve (MFR) by positron emission tomography (PET), has emerged as a key mediator of risk. We aimed to assess whether PET MFR provides additive value for risk stratification of cardiometabolic disease patients compared with single-photon emission computed tomography (SPECT) MPI.

METHODS

We retrospectively followed patients referred for PET, exercise SPECT, or pharmacologic SPECT MPI with cardiometabolic disease (obesity, diabetes, or chronic kidney disease) and without known CAD. We compared rates and hazards of composite major adverse cardiovascular events (MACEs) (annualized cardiac mortality or acute myocardial infarction) among propensity-matched PET and SPECT patients using Poisson and Cox regression. Normal SPECT was defined as a total perfusion deficit (TPD) of <5%, reflecting the absence of obstructive CAD. Normal PET was defined as a TPD of <5% plus an MFR of ≥2.0.

RESULTS

Among 21,544 patients referred from 2006 to 2020, cardiometabolic disease was highly prevalent (PET: 2308 [67%], SPECT: 9984 [55%]) and higher among patients referred to PET (P < 0.001). Obstructive CAD findings (TPD > 5%) were uncommon (PET: 21% and SPECT: 11%). Conversely, impaired MFR on PET (<2.0) was common (62%). In a propensity-matched analysis over a median 6.4-year follow-up, normal PET identified low-risk (0.9%/year MACE) patients, and abnormal PET identified high-risk (4.2%/year MACE) patients with cardiometabolic disease; conversely, those with normal pharmacologic SPECT remained moderate-risk (1.6%/year, P < 0.001 compared to normal PET).

CONCLUSIONS

Cardiometabolic disease is common among patients referred for MPI and is associated with a heterogenous level of risk. Compared with pharmacologic SPECT, PET with MFR can detect nonobstructive CAD including CMD and can more accurately discriminate low-risk from higher-risk individuals.

A machine learning-based approach to directly compare the diagnostic accuracy of myocardial perfusion imaging by conventional and cadmium-zinc telluride SPECT

BACKGROUND

We evaluated the performance of conventional (C) single-photon emission computed tomography (SPECT) and cadmium-zinc-telluride (CZT)-SPECT in a large cohort of patients with suspected or known coronary artery disease (CAD) and compared the diagnostic accuracy of the two systems using machine learning (ML) algorithms.

METHODS AND RESULTS

A total of 517 consecutive patients underwent stress myocardial perfusion imaging (MPI) by both C-SPECT and CZT-SPECT. In the overall population, an excellent correlation between stress MPI data and left ventricular (LV) functional parameters measured by C-SPECT and by CZT-SPECT was observed (all P < .001). ML analysis performed through the implementation of random forest (RF) and k-nearest neighbors (NN) algorithms proved that CZT-SPECT has greater accuracy than C-SPECT in detecting CAD. For both algorithms, the sensitivity of CZT-SPECT (96% for RF and 60% for k-NN) was greater than that of C-SPECT (88% for RF and 53% for k-NN).

CONCLUSIONS

MPI data and LV functional parameters obtained by CZT-SPECT are highly reproducible and provide good correlation with those obtained by C-SPECT. ML approach showed that the accuracy and sensitivity of CZT-SPECT is greater than C-SPECT in detecting CAD.

Preoperative Cardiac Diagnostics in Bariatric Patients with Diabetes and Perioperative Morbidity: Results of a Cohort of 258 Patients

Purpose

The combination of obesity and diabetes mellitus are well-known risk factors for cardiovascular complications and perioperative morbidity in metabolic surgery. The aim of this study was to evaluate effectivity and reliability of the cardiac assessment in patients with diabetes prior to bariatric surgery.

Setting

Private, university-affiliated teaching hospital, Switzerland

Material and Methods

Retrospective analysis of prospectively collected data on results and consequences of cardiac assessments in 258 patients with obesity and diabetes scheduled for primary bariatric surgery at our institution between January 2010 and December 2018.

Results

Out of 258 patients, 246 (95.3%) received cardiac diagnostics: 173 (67.1%) underwent stress-rest myocardial perfusion scintigraphy (MPS), 15 (5.8%) patients had other cardiac imaging including cardiac catheterization, 58 (22.5%) patients had echocardiography and/or stress electrocardiography, and 12 (4.7%) patients received no cardiac evaluation. Subsequently, cardiac catheterization was performed in 28 patients (10.9%), and coronary heart disease was detected and treated in 15 subjects (5.8%). Of these 15 individuals, 5 (33.3%) patients had diffuse vascular sclerosis, 8 (53.3%) patients underwent coronary angioplasty and stenting, and 2 (13.3%) patients coronary artery bypass surgery. Bariatric surgery was performed without perioperative cardiovascular events in all 258 patients.

Conclusion

Our data suggest that a detailed cardiac assessment is mandatory in bariatric patients with diabetes to identify those with yet unknown cardiovascular disease before performing bariatric surgery. We recommend carrying out myocardial perfusion scintigraphy as a reliable diagnostic tool in this vulnerable population. If not viable, stress echocardiography should be performed as a minimum.

Automated Inline Analysis of Myocardial Perfusion MRI with Deep Learning

Purpose

To develop a deep neural network–based computational workflow for inline myocardial perfusion analysis that automatically delineates the myocardium, which improves the clinical workflow and offers a “one-click” solution.

Materials and Methods

In this retrospective study, consecutive adenosine stress and rest perfusion scans were acquired from three hospitals between October 1, 2018 and February 27, 2019. The training and validation set included 1825 perfusion series from 1034 patients (mean age, 60.6 years ± 14.2 [standard deviation]). The independent test set included 200 scans from 105 patients (mean age, 59.1 years ± 12.5). A convolutional neural network (CNN) model was trained to segment the left ventricular cavity, myocardium, and right ventricle by processing an incoming time series of perfusion images. Model outputs were compared with manual ground truth for accuracy of segmentation and flow measures derived on a global and per-sector basis with t test performed for statistical significance. The trained models were integrated onto MR scanners for effective inference.

Results

The mean Dice ratio of automatic and manual segmentation was 0.93 ± 0.04. The CNN performed similarly to manual segmentation and flow measures for mean stress myocardial blood flow (MBF; 2.25 mL/min/g ± 0.59 vs 2.24 mL/min/g ± 0.59, P = .94) and mean rest MBF (1.08 mL/min/g ± 0.23 vs 1.07 mL/min/g ± 0.23, P = .83). The per-sector MBF values showed no difference between the CNN and manual assessment (P = .92). A central processing unit–based model inference on the MR scanner took less than 1 second for a typical perfusion scan of three slices.

Conclusion

The described CNN was capable of cardiac perfusion mapping and integrated an automated inline implementation on the MR scanner, enabling one-click analysis and reporting in a manner comparable to manual assessment.

Published under a CC BY 4.0 license.

Supplemental material is available for this article.

Myocardial perfusion imaging for diabetes: Key points from the evidence and clinical questions to be answered

Diabetes represents a worldwide increasing problem and cardiovascular disease is the most common cause of death in diabetic patients. Pathophysiology that links diabetes to cardiovascular disease is a complex and multifactorial phenomenon evolving over time and involving both large blood vessels (macrovasculature) and small blood vessels (microvasculature). Myocardial perfusion imaging (MPI) imaging by both single-photon emission computer tomography and positron emission tomography with different specific tracers has become an indispensable tool for discriminating normal from diseased myocardial tissues and left ventricular function and monitoring myocardial blood flows, leading to the evaluation of almost overall physiologic consequences of the macro- and microvascular impairment involved in diabetic patients. This review will provide an overview of the role of MPI in the diagnosis and risk assessment of patients with diabetes and suspected or known CAD.

Long-term prognostic value of low-dose normal stress-only myocardial perfusion imaging by wide beam reconstruction: A competing risk analysis

BACKGROUND

A normal stress myocardial perfusion single-photon emission computed tomography (MPS) is associated with a good clinical outcome. New iterative algorithms, such as wide beam reconstruction (WBR), which improve image interpretation with half-dose or half-time acquisition, have been proposed for cardiac MPS. The aim of this study was to assess the long-term predictive value of a low-dose normal stress-only MPS with WBR using conventional Anger camera in patients with known or suspected coronary artery disease (CAD).

METHODS AND RESULTS

A total of 2106 patients with known or suspected CAD and normal perfusion at half-dose stress-only MPS protocol were followed for a mean of 6.6 ± 2.7 years. MPS data were reconstructed with WBR iterative algorithm. End-point events were cardiac death or nonfatal myocardial infarction. Noncardiac death was considered the competing event. During follow-up, 149 cardiac events occurred with an annualized event rate of 1.2%. Independent predictors of cardiac events at Cox analysis were age, male gender, diabetes mellitus, previous myocardial infarction and the need for pharmacologic stress testing. At Fine-Gray analysis the cumulative incidence of cardiac events progressively increases with age and in the presence of diabetes for any combination of gender and stress type. Survival tree analysis confirmed that long-term prognosis considerably varies according of risk factors profile.

CONCLUSIONS

Low-dose normal stress-only WBR MPS has a reliable long-term prognostic value in patients with suspected or known CAD. This finding supports the introduction of such a method into clinical practice with a consistent dose optimization in the interest of patients and exposed staff.

Added prognostic value of left ventricular shape by gated SPECT imaging in patients with suspected coronary artery disease and normal myocardial perfusion

BACKGROUND

Left ventricular (LV) remodeling is associated with adverse cardiovascular events. We evaluated the added prognostic value of LV shape index (SI) assessed by gated single-photon emission tomography (SPECT) in patients without known coronary artery disease (CAD).

METHODS AND RESULTS

We studied 674 patients with normal myocardial perfusion and normal LV ejection fraction (EF) on stress gated SPECT imaging. An automated software program was used to calculate end-diastolic and end-systolic LVSI. An LVSI ≤ 0.54 at end-systole was considered normal. Follow-up was 96% complete with a median follow-up of 37 months. During follow-up, 25 events occurred (3.8% cumulative event rate). Event-free survival was lower in patients with abnormal end-systolic LVSI (P < .001). Age (P = .021), diabetes (P = .048), and end-systolic LVSI (P < .001) were independent predictors of events. LVSI added prognostic information increasing the global chi-square of the model including age and diabetes from 15.15 to 25.97 (P < .001). The effect of diabetes on hazard ratio increased with increasing values of end-systolic LVSI. The probability of events at 48 months predicted by Weibull analysis progressively increased with increasing values of end-systolic LVSI and was higher in patients with diabetes as compared to those without. Decision curve analyses indicate that the model including end-systolic LVSI resulted in an increased net benefit between 5% and 30% threshold probability, indicating superior estimation of outcomes at low threshold probability levels.

CONCLUSIONS

The evaluation of LVSI may identify patients with early-stage LV remodeling and at higher risk of adverse cardiac events, even in the presence of normal myocardial perfusion.

Comparison of left ventricular shape by gated SPECT imaging in diabetic and nondiabetic patients with normal myocardial perfusion: A propensity score analysis

BACKGROUND

Diabetes mellitus induces structural and functional cardiac alterations that can result in heart failure. Left ventricular (LV) shape is a dynamic component of cardiac geometry influencing its contractile function. However, few data are available comparing LV shape index in diabetic and nondiabetic patients without overt coronary artery disease after balancing for coronary risk factors.

METHODS

We studied 1168 patients with normal myocardial perfusion and normal LV ejection fraction on stress gated single-photon emission computed tomography (SPECT) imaging. To account for differences in baseline characteristics between diabetic and nondiabetic patients, we created a propensity score-matched cohort considering clinical variables, coronary risk factors, and stress type.

RESULTS

Before matching, diabetic patients were older, had higher prevalence of male gender and coronary risk factors, and higher end-diastolic and end-systolic LV shape index. After matching, all clinical characteristics were comparable between diabetic and nondiabetic patients, but diabetic patients still had higher end-diastolic and end-systolic LV shape index (both P < .001). At multivariable linear regression analysis, diabetes was a strong predictor of end-systolic LV shape index in the overall study population and in the propensity-matched cohort.

CONCLUSIONS

Diabetic patients have higher values of LV shape index compared to nondiabetic patients also after balancing clinical characteristics by propensity score analysis. Shape indexes assessment by gated SPECT may be useful for identifying early LV remodeling in patients with diabetes.

Prognostic implications of myocardial perfusion imaging and coronary calcium score in a Macedonian cohort of asymptomatic patients with type 2 diabetes

AIM

Type 2 diabetes is a risk factor for coronary artery disease; however, a number of studies have shown that patients are asymptomatic for coronary artery disease. The presence of coronary artery disease in asymptomatic patients with type 2 diabetes was evaluated to determine its impact on management decision and prognosis.

METHODS

A total of 75 patients underwent single-photon emission computed tomography myocardial perfusion imaging for detection of suspected coronary artery disease. We used 17-segment model for perfusion and function analysis. Multislice computed tomography was performed in 45 patients to assess coronary artery calcium. Complete laboratory analyses with lipid values and standard risk factors were analysed. Forward logistic regression analysis was used to assess predictive parameters for myocardial ischaemia during the follow-up period of 20 ± 4 months.

RESULTS AND CONCLUSION

Silent myocardial ischaemia and subclinical coronary artery disease can be detected in a significant proportion of asymptomatic patients with type 2 diabetes. Diabetic patients with normal myocardial perfusion imaging had an excellent 2-year prognosis with optimal medical therapy and intensive risk factor control. In comparison, an abnormal myocardial perfusion imaging led to an increased risk of cardiovascular events. Myocardial perfusion imaging and coronary artery calcium are valuable tools for risk stratification and optimal treatment decision in this asymptomatic diabetic cohort of Macedonian patients.

Cardiovascular Screening for the Asymptomatic Patient with Diabetes: More Cons Than Pros

Diabetes mellitus is associated with an increased risk of coronary heart disease (CHD) morbidity and mortality. Although it frequently coexists with other cardiovascular disease (CVD) risk factors, it confers an increased risk for CVD events on its own. Coronary atherosclerosis is generally more aggressive and widespread in people with diabetes (PWD) and is frequently asymptomatic. Screening for silent myocardial ischaemia can be applied in a wide variety of ways. In nearly all asymptomatic PWD, however, the results of screening will generally not change medical therapy, since aggressive preventive measures, such as control of blood pressure and lipids, would have been already indicated, and above all, invasive revascularization procedures (either with percutaneous coronary intervention or coronary artery bypass grafting) have not been shown in randomized clinical trials to confer any benefit on morbidity and mortality. Still, unresolved issues remain regarding the extent of the underlying ischaemia that might affect the risk and the benefit of revascularization (on top of optimal medical therapy) in ameliorating this risk in patients with moderate to severe ischaemia. The issues related to the detection of coronary atherosclerosis and ischaemia, as well as the studies related to management of CHD in asymptomatic PWD, will be reviewed here.

Long-term prognostic value of stress myocardial perfusion imaging and coronary computed tomography angiography: A meta-analysis

BACKGROUND

We conducted a meta-analysis to compare the long-term prognostic value of stress single-photon emission computed tomography myocardial perfusion imaging (MPI) and coronary computed tomography angiography (CCTA) for adverse cardiovascular events in subjects with suspected or known coronary artery disease.

METHODS AND RESULTS

We searched PubMed, Cochrane, Web of Science, and Scopus database between January 2000 and December 2014 for stress MPI and CCTA studies that followed up ≥ 100 subjects for ≥ 2.5 years and provided the unadjusted and/or adjusted hazard ratio (HR) at Cox regression analysis. Summary risk estimates for abnormal perfusion at MPI or ≥ 50% coronary stenosis at CCTA were derived in random effect regression analysis, and causes of heterogeneity were determined in meta-regression analysis. We identified 21 eligible articles (10 MPI and 11 CCTA) including 25,258 participants (13,484 in MPI and 11,774 in CCTA studies) with suspected or known coronary artery disease. Among the included publications, 8 MPI and 8 CCTA studies reported the HR for the occurrence of hard events (death and nonfatal myocardial infarction). The pooled HR was comparable for MPI and CCTA studies. The HR for the occurrence of a combined endpoint including revascularization as event was reported in 4 MPI and 6 CCTA studies. The pooled HR was higher for CCTA compared to MPI (P < .05) also when only MPI and CCTA studies with limited representation of prior CAD were considered.

CONCLUSIONS

The long-term prognostic value of MPI and CCTA for the occurrence of hard events is similar. However, the association between event-free survival and CCTA is higher than MPI when coronary revascularization is included in the endpoint.

Long-Term Survival Benefit of Coronary Revascularization in Patients Undergoing Stress Myocardial Perfusion Imaging

BACKGROUND

We assessed the relationship between clinical outcome and coronary revascularization according to stress-gated myocardial perfusion single-photon emission computed tomography (MPS) in an observational series of patients with suspected or known coronary artery disease (CAD), on long-term follow-up.

METHODS AND RESULTS

The study group consisted of 2,059 patients. During a median follow-up of 61 months, 184 events occurred (126 cardiac deaths and 58 non-fatal MI). The impact of revascularization during follow-up on event-free survival was evaluated using an extended Cox regression model, adjusting for potential clinical and MPS confounders. Revascularization was treated as a binary non-reversible time-dependent covariate. Predefined interactions tested were: (1) revascularization and summed difference score (SDS); (2) revascularization and post-stress left ventricular (LV) ejection fraction (EF); and (3) SDS and post-stress LVEF. Revascularization had a significant effect on event-free survival (adjusted HR, 0.19; P<0.001). Significant interactions were found between revascularization and SDS (P=0.045), and between LVEF and SDS (P=0.015). The protective effect of revascularization increased as SDS increased. For SDS <6 the reduction in HR was detectable only for reduced LVEF.

CONCLUSIONS

Both the degree of stress-induced ischemia and LVEF predict the effect of revascularization on outcome in patients with suspected or known CAD. The protective effect of revascularization appears to be greater in patients with severe ischemia and preserved LVEF.

Prevalence and Severity of Myocardial Perfusion Imaging Abnormalities in Inmate Subjects

Aim

We evaluated the prevalence and severity of myocardial perfusion abnormalities among inmates undergoing cardiac single-photon emission computed tomography. We also compared the results with those obtained in a cohort of non-inmates.

Methods

Between January 2009 and December 2013, 2420 consecutive subjects (258 inmates and 2162 non-inmates) with suspected or known coronary artery disease underwent stress myocardial perfusion single-photon emission computed tomography (MPS) to our institution. The decision to submit inmates to MPS was taken by the physicians of the penal institutions or ordered by the court based on the survey of part. To account for differences in clinical characteristics between inmates and non-inmates, we created a propensity score-matched cohort considering clinical variables and stress type.

Results

Before matching, inmates were younger and had higher prevalence of male gender, smoking, chest pain, and previous myocardial infarction or revascularization (all p < 0.001). After matching, all characteristics were comparable in 258 inmates and 258 non-inmates. The total amount of abnormal myocardium was similar in inmates and non-inmates before and after matching. Infarct size and severity were larger in inmates before (p < 0.001) and after (p < 0.01) matching and left ventricular ejection fraction was lower in inmates compared to non-inmates (p < 0.01).

Conclusions

Detention is associated with larger infarct size compared to a general population of subjects referred to stress MPS also after matching for clinical variables and stress type. The similar prevalence of normal MPS in the matched cohort suggests that this imaging technique might be appropriate in inmates.

Investigating the Generalizability of Economic Evaluations Conducted in Italy: A Critical Review

OBJECTIVES

To assess the methodological quality of Italian health economic evaluations and their generalizability or transferability to different settings.

METHODS

A literature search was performed on the PubMed search engine to identify trial-based, nonexperimental prospective studies or model-based full economic evaluations carried out in Italy from 1995 to 2013. The studies were randomly assigned to four reviewers who applied a detailed checklist to assess the generalizability and quality of reporting. The review process followed a three-step blinded procedure. The reviewers who carried out the data extraction were blind as to the name of the author(s) of each study. Second, after the first review, articles were reassigned through a second blind randomization to a second reviewer. Finally, any disagreement between the first two reviewers was solved by a senior researcher.

RESULTS

One hundred fifty-one economic evaluations eventually met the inclusion criteria. Over time, we observed an increasing transparency in methods and a greater generalizability of results, along with a wider and more representative sample in trials and a larger adoption of transition-Markov models. However, often context-specific economic evaluations are carried out and not enough effort is made to ensure the transferability of their results to other contexts. In recent studies, cost-effectiveness analyses and the use of incremental cost-effectiveness ratio were preferred.

CONCLUSIONS

Despite a quite positive temporal trend, generalizability of results still appears as an unsolved question, even if some indication of improvement within Italian studies has been observed.

Prognostic value of normal stress myocardial perfusion imaging in diabetic patients: a meta-analysis

BACKGROUND

The prognostic value of normal stress myocardial perfusion single-photon emission computed tomography (MPS) in patients with diabetes has only been evaluated in single-center studies of relatively limited sample size. We performed a meta-analysis of published studies, including diabetic patients with known or suspected coronary artery disease (CAD), to assess the predictive value for adverse cardiac ischemic events of normal stress MPS.

METHODS AND RESULTS

Studies published between January 1990 and December 2013 were identified by database search. We included studies using stress MPS to evaluate diabetic patients with known or suspected CAD and providing data on clinical outcomes of non-fatal myocardial infarction or cardiac death with a follow-up time ≥12 months. A total of 14 studies were finally included, recruiting 13,493 patients. The negative predictive value (NPV) for non-fatal myocardial infarction and cardiac death of normal MPS was 94.92% (95% confidence interval 93.67-96.05), during a weighted mean follow-up of 36.24 months, resulting in estimated event rate after a negative test equal to 5.08% (95% confidence interval 3.95-6.33). The corresponding annualized event rate after a negative test was 1.60% (95% confidence interval 1.21-2.04).

CONCLUSIONS

Stress MPS has a high NPV for adverse cardiac events in diabetic patients with known or suspected CAD leading to define a "relatively low-risk" patients category.

PLGA nanoparticles loaded with host defense peptide LL37 promote wound healing

Wound treatment remains one of the most prevalent and economically burdensome healthcare issues in the world. Poly (lactic-co-glycolic acid) (PLGA) supplies lactate that accelerates neovascularization and promotes wound healing. LL37 is an endogenous human host defense peptide that modulates wound healing and angiogenesis and fights infection. Hence, we hypothesized that the administration of LL37 encapsulated in PLGA nanoparticles (PLGA-LL37 NP) promotes wound closure due to the sustained release of both LL37 and lactate. In full thickness excisional wounds, the treatment with PLGA-LL37 NP significantly accelerated wound healing compared to PLGA or LL37 administration alone. PLGA-LL37 NP-treated wounds displayed advanced granulation tissue formation by significant higher collagen deposition, re-epithelialized and neovascularized composition. PLGA-LL37 NP improved angiogenesis, significantly up-regulated IL-6 and VEGFa expression, and modulated the inflammatory wound response. In vitro, PLGA-LL37 NP induced enhanced cell migration but had no effect on the metabolism and proliferation of keratinocytes. It displayed antimicrobial activity on Escherichia coli. In conclusion, we developed a biodegradable drug delivery system that accelerated healing processes due to the combined effects of lactate and LL37 released from the nanoparticles.

Reclassification of cardiovascular risk by myocardial perfusion imaging in diabetic patients with abnormal resting electrocardiogram

BACKGROUND AND AIMS

Despite an extensive use of stress myocardial perfusion single-photon emission computed tomography (MPS), no study addressed the role of perfusion imaging in diabetic patients with abnormal resting electrocardiogram (ECG). We compared analytical approaches to assess the added value of stress MPS variables in estimating coronary heart disease outcomes in diabetic patients with abnormal resting ECG.

METHODS AND RESULTS

A total of 416 patients with diabetes and abnormal resting ECG who underwent stress MPS were prospectively followed up after the index study. The end point was the occurrence of a major cardiac event, including cardiac death and nonfatal myocardial infarction. At the end of follow-up (median 58 months), 42 patients experienced events. MPS data increased the predictive value of a model including traditional cardiovascular risk factors and left ventricular (LV) ejection fraction (likelihood ratio χ² from 17.54 to 24.15, p < 0.05, with a C statistic of 0.72, 95% confidence interval: 0.65-0.79). The addition of MPS data resulted in reclassification of 25% of the sample with a net reclassification improvement of 0.20 (95% confidence interval: 0.05-0.36). Overall, 63 patients were reclassified to a lower risk category, with a 5-year event rate of 3.5%, and 40 patients were reclassified to a higher risk category, with a 5-year event rate of 20%.

CONCLUSION

The addition of MPS findings to a model based on traditional cardiovascular risk factors and LV ejection fraction improves risk classification for incident cardiac events in diabetic patients with abnormal resting ECG.

Warranty period of normal stress myocardial perfusion imaging in diabetic patients: a propensity score analysis

BACKGROUND

We evaluated the relationship between diabetes and temporal characteristics of cardiac risk at long-term follow-up in a propensity score-matched cohort of diabetic and non-diabetic patients with normal stress myocardial perfusion single-photon emission computed tomography (MPS).

METHODS AND RESULTS

We studied 828 consecutive patients with suspected or known coronary artery disease and normal perfusion at stress MPS. To account for differences in baseline characteristics between diabetics and non-diabetics, we created a propensity score-matched cohort considering clinical variables and stress type. After matching, clinical characteristics were comparable in 260 diabetic and 260 non-diabetic patients. All patients were followed for at least 1 year (median 53 months). End-point events were cardiac death or nonfatal myocardial infarction. At Cox analysis, diabetes (hazard ratio 3.9, P < .01) and post-stress left ventricular ejection fraction (LVEF) ≤45% (hazard ratio 4.1, P < .01) were independent predictors of events. At parametric analysis, non-diabetic patients with post-stress LVEF >45% remained at low risk for the entire length of follow-up, while the highest probability of events and the major risk acceleration was observed in patients with diabetes and post-stress LVEF ≤45%.

CONCLUSIONS

After a normal stress MPS, diabetic patients are at higher risk for cardiac events than non-diabetic subjects also after balancing clinical characteristics and stress type by propensity score analysis. The warranty period of a normal stress MPS varies according to diabetic status and post-stress LVEF.

Metabolic syndrome is not a predictor for cardiovascular events in Japanese patients with diabetes mellitus asymptomatic for coronary artery disease: a retrospective analysis of the J-ACCESS-2 study

PURPOSE

Patients with metabolic syndrome (MetS) have potentially higher risk for cardiovascular events. The aim of this study was to evaluate the effect of MetS on cardiac events in type-2 diabetic patients asymptomatic for coronary artery disease (CAD) in a Japanese population.

METHODS

A total of 485 patients from a J-ACCESS-2 investigation with stress-gated myocardial perfusion imaging (MPI) and quantitative-gated MPI analysis were examined. Cardiovascular hard events (cardiac death and acute coronary syndrome) and total events during a 3-year follow-up were analyzed.

RESULTS

The MetS group (n = 229) had higher incidence of hypertension, dyslipidemia, and ventricular dilatation than the non-MetS group (n = 256). The hard events were 8 and 12 for the MetS and non-MetS groups (P = n.s.), and total events were 31 and 31 for each of these groups, respectively (P = n.s.). Significant variables related to total cardiovascular events included age, current smoking, insulin use, total cholesterol, ejection fraction, summed stress score ≥ 9, and summed difference score ≥ 2. Cox proportional hazard analysis and Kaplan-Meier survival analysis showed that only the summed stress score was related to total events (P = .01), and the presence and the number of items for MetS criteria were not.

CONCLUSION

In patients with type 2 diabetes asymptomatic for CAD, cardiovascular events and ischemia are as common in diabetic patients without MetS as in those with MetS. A high MPI defect score is related to total events including cardiac and cerebrovascular events.

Prevalence and predictors of ischemia and outcomes in outpatients with diabetes mellitus referred for single-photon emission computed tomography myocardial perfusion imaging

Background- The prevalence of ischemia and its prediction of events are unclear in outpatients with diabetes mellitus in the modern era of intensive medical management. We sought to identify the prevalence of ischemia, subsequent cardiac events, and impact of sex, stress type, and symptom status on these findings in a cohort of stable outpatients with diabetes mellitus referred for single-photon emission computed tomography myocardial perfusion imaging (MPI). Methods and Results- The study cohort included 575 consecutive outpatients with diabetes mellitus who underwent quantitative, gated single-photon emission computed tomography MPI. Clinical information, stress MPI variables, and cardiac events were prospectively collected and analyzed. The study population was at intermediate risk of coronary artery disease or had known coronary artery disease (40.3%); 29% of patients were asymptomatic at the time of stress testing. Scintigraphic ischemia and significant (≥10%) left ventricular ischemia were present in 126 patients (21.9%) and 29 patients (5.0%), respectively, and <1% of patients had early revascularization. The risk of ischemia was increased >2-fold by male sex (P<0.001), but was not impacted by pharmacological stress (P=0.15) or presence of symptoms (P=0.89). During a median 4.4 years follow-up, the rate of cardiac death/nonfatal myocardial infarction was moderate at 2.6%/y (cardiac death 0.8%/y) in the total cohort, but was 5.7%/y in those with ischemia (P<0.001). Pharmacological stress predicted a higher cardiac event rate (P<0.001) but symptoms did not (P=0.55). Conclusions- This cohort of stable outpatients with diabetes mellitus referred for single-photon emission computed tomography had low rates of significant ischemia and early revascularization; an initially low cardiac event rate increased after 2 years. Independent predictors of cardiac death/nonfatal myocardial infarction were known coronary artery disease, pharmacological stress, and MPI ischemia. Nearly one third of those with events had a normal MPI, indicating a need for improved risk stratification.

Transient ischemic dilation in SPECT myocardial perfusion imaging for prediction of severe coronary artery disease in diabetic patients

BACKGROUND

Transient ischemic dilation (TID) of the left ventricle during stress myocardial perfusion SPECT (MPS) has been shown to be a useful marker of severe coronary artery disease (CAD). However, investigations in diabetic patients with available coronary angiographic data are still limited. We evaluated the incremental diagnostic value of TID in identifying the presence of angiographically severe CAD in diabetic patients.

METHODS AND RESULTS

TID ratio values were automatically derived from rest-stress MPS in 242 diabetic patients with available coronary angiography data. A cutoff of ≥1.19 was considered to represent TID. Severe CAD (≥70% stenosis in the proximal left anterior descending artery or the left main artery, or ≥90% stenosis in two or three vessels) was identified in 69 (29%) patients. At multivariate analysis, the best independent predictors of severe CAD were summed stress score and TID (both P < .001). At incremental analysis, the addition of TID improved the power of a model including clinical data and summed stress score, increasing the global χ(2) value from 14.3 to 28.2 (P < .01). The best cutoff of summed stress score for identifying patients with severe CAD was ≥8. When the TID ratio was considered in patients with summed stress score between 3 and 7, the sensitivity for diagnosing severe CAD significantly improved from 71% to 77% (P < .05). In the overall study population, the net reclassification improvement by adding TID to a model including clinical data and summed stress score in the prediction of severe CAD was 0.40 (P < .005).

CONCLUSIONS

TID ratios obtained from rest-stress MPS provide incremental diagnostic information to standard perfusion analysis for the identification of severe and extensive CAD in diabetic patients.

Incremental prognostic value of stress myocardial perfusion imaging in asymptomatic diabetic patients

OBJECTIVE

Stress myocardial perfusion single-photon emission computed tomography (MPS) variables are robust estimators of prognosis. No data are available on the comparative ability of stress MPS risk markers using varied iterative and risk classification approaches in asymptomatic diabetic patients. We compared analytical approaches to estimate the added value of MPS variables in estimating coronary artery disease (CAD) outcomes in asymptomatic diabetic patients. We also evaluated the temporal characteristics of cardiac risk according to MPS findings.

METHODS

A total of 436 consecutive asymptomatic diabetic patients who underwent stress-rest gated MPS were prospectively enrolled. Multivariable Cox proportional hazards model was employed to estimate cardiac death and nonfatal myocardial infarction (MI). Risk reclassification was calculated and parametric survival analysis was used to predict time to events.

RESULTS

At multivariable analysis, post-stress left ventricular ejection fraction (LVEF) and stress MPS ischemia were independent predictors of CAD death or MI (both p < 0.01). The net reclassification improvement by adding MPS results to a model including pre-test CAD likelihood was 0.25 (95% confidence interval 0.06-0.44; p < 0.01). Parametric survival analysis showed the highest probability of CAD death or MI and the major risk acceleration in time in patients with stress MPS ischemia and post-stress LVEF ≤45%.

CONCLUSION

In asymptomatic diabetic patients, analytical approaches that establish the reclassification of events may serve for estimation of improved outcomes for stress MPS. Post-stress LVEF and stress-induced ischemia by gated MPS influence the temporal characteristic of the patient's risk at long-term follow-up.

Microalbuminuria predicts silent myocardial ischaemia in type 2 diabetes patients

PURPOSE

Myocardial ischaemia is frequently silent in patients with type 2 diabetes. Although it has been proposed as a potential screening tool, the role of myocardial perfusion single photon emission computed tomography (MPS) has recently been questioned, due to the low prevalence of positive scans and the low rate of cardiac events. The aim of this study was to assess if pretest clinical variables can identify a subgroup of asymptomatic patients with type 2 diabetes at risk of silent myocardial ischaemia and a subsequent poor outcome

METHODS

This prospective study included 77 patients (50 men, mean age 63 ± 9 years) with type 2 diabetes and no known coronary artery disease (CAD) or angina pectoris who underwent gated MPS to screen for CAD between March 2006 and October 2008. MPS images were interpreted using a semiquantitative visual 20-segment model to define summed stress, rest and difference scores. Ischaemia was defined as a sum difference score (SDS) ≥2. Patients were followed-up (median 4.1 years, range 0.8 - 6.1 years) and cardiac hard events (cardiac death or nonfatal myocardial infarction) were recorded.

RESULTS

Silent ischaemia was detected in 25 of the 77 patients (32 %). Specifically, 10 patients (13 %) had mild ischaemia (SDS 2 to ≤4) and 15 patients (19 %) had severe ischaemia (SDS >4). In univariate binary logistic analysis, microalbuminuria was the only significant predictor of silent ischaemia on MPS (odds ratio 4.42, 95 % CI 1.27 - 15.40; P = 0.019). The overall accuracy of microalbuminuria for predicting silent ischaemia was 71.4 % and was 89.6 % for predicting severe ischaemia. Kaplan-Meier curves showed no significant group differences in 5-year cardiac event-free survival between patients with and those without microalbuminuria, or between patients with SDS ≥2 and those with SDS <2. In contrast, 5-year event-free survival was significantly lower in patients with SDS >4 than in patients with SDS ≤4: 55.6 % (95 % CI 39.0 - 72.2 %) vs. 94.5 % (95 % CI: 91.4 - 97.6 %), respectively (Breslow test, chi-square 20.9, P < 0.001). Median cardiac event-free survival was not observed in the whole group, while the 25th percentile of cardiac event-free survival was reached only in patients with SDS >4 (2.3 years). In univariate Cox regression analysis, SDS >4 predicted cardiac event-free survival (hazard ratio 12.87, 95 % CI 2.86 - 27.98; P = 0.001), while SDS ≥2 did not (hazard ratio 2.78, 95 % CI 0.62 - 12.46, P = 0.16).

CONCLUSION

In this group of patients with type 2 diabetes, microalbuminuria was the only predictor of silent ischaemia on MPS. Assessment of microalbuminuria should be routinely considered among the first risk stratification steps for CAD in patients with type 2 diabetes, even though severe ischaemia on MPS is a major predictor of cardiac event-free survival.

Prediction models for risk classification in cardiovascular disease

Risk stratification is an increasingly important tool for the management of patients with different diseases and also for decision making in subjects not yet with overt disease but who are at risk of disease in the short or long term or during their lifetime. Careful risk assessment in the individual patient, based on clinical, laboratory and imaging data, can be helpful for making decisions about treatment or other prevention strategies. As regards cardiovascular disease, many models have been suggested and are available for the prediction of diagnosis and prognosis and there are several algorithms for risk prediction. However, current risk screening methods are not perfect. This review evaluates relative strengths and limitations of traditional and more recent methods for assessing the performance of prediction models.