Relation between myocardial blood flow and cardiac events in diabetic patients with suspected coronary artery disease and normal myocardial perfusion imaging

Impact on cardiovascular outcome of coronary revascularization-induced changes in ischemic perfusion defect and myocardial flow reserve

PURPOSE

We evaluated the impact on cardiovascular outcome of coronary revascularization-induced changes in ischemic total perfusion defect (ITPD) and myocardial flow reserve (MFR) as assessed by 82Rb positron emission tomography (PET)/computed tomography (CT) imaging.

METHODS

The study included 102 patients referred to 82Rb PET/CT myocardial perfusion imaging before and after coronary revascularization. All patients were followed for the occurrence of cardiovascular events (cardiac death, nonfatal myocardial infarction, repeated revascularization, and heart failure) after the second imaging study.

RESULTS

During a median follow-up of 20 months, 21 events occurred. The clinical characteristics were comparable between patients with and without events. In the overall study population, after revascularization, there was a significant reduction (P < 0.001) of ITPD, while hyperemic myocardial blood flow (MBF) (P < 0.01) and MFR (P < 0.05) significantly improved. Event rate was higher in patients with ITPD (P < 0.005) or MFR (P < 0.001) worsening compared to those with unchanged or improved ITPD or MFR. At Cox univariable analysis, ITPD and MFR worsening resulted in predictors of events (both P < 0.05). Patients with worsening of both ITPD and MFR had the worst event-free survival (log-rank 32.9, P for trend < 0.001).

CONCLUSIONS

In patients with stable CAD, worsening of ITPD and MFR after revascularization procedures is associated with higher risk of cardiovascular events. Follow-up MPI with 82Rb PET/CT may improve risk stratification in patients submitted to coronary revascularization.

Prevalence and Prognostic Importance of Abnormal Positron Emission Tomography Among Asymptomatic Patients With Diabetes Mellitus

BACKGROUND

Ischemia and reduced global myocardial blood flow reserve (MBFR) are associated with high cardiovascular risk among symptomatic patients with diabetes mellitus (DM).

OBJECTIVES

This study aimed to assess the prevalence and prognostic importance of silent ischemia and reduced MBFR among asymptomatic patients with DM.

METHODS

This study included 2,730 consecutive patients with DM, without known coronary artery disease (CAD) or cardiomyopathy, who underwent rubidium-82 rest/stress positron emission tomography (PET) myocardial perfusion imaging (MPI) from 2010 to 2016. These patients were followed up for all-cause mortality (n = 461) for a median follow-up of 3 years. Patients were considered asymptomatic if neither chest pain nor dyspnea was elicited. Rates of ischemia, reduced MBFR, and coronary microvascular dysfunction on PET were assessed in both groups. Cox regression was used to define the independent association of abnormal MPI markers with mortality.

RESULTS

One-quarter of patients with DM (23.7%; n = 647) were asymptomatic; ischemia was present in 30.5% (n = 197), reduced MBFR in 62.3% (n = 361), and coronary microvascular dysfunction in 32.7% (n = 200). In adjusted analyses, reduced MBFR (HR per 0.1 unit decrease in MBFR: 1.08 [95% CI: 1.03-1.12]; P = 0.001) and reduced ejection fraction (HR per 5% decrease: 1.10 [95% CI: 1.01-1.18]; P = 0.02) were independently prognostic of mortality among asymptomatic patients, but ischemia was not. This was comparable to DM patients with symptoms. Insulin use and older age were significant predictors of reduced MBFR among asymptomatic patients with DM.

CONCLUSIONS

In both symptomatic and asymptomatic patients with DM, impairment in MBFR is common and associated with greater mortality risk.

Coronary Microvascular Dysfunction and Diffuse Myocardial Fibrosis in Patients With Type 2 Diabetes Using Quantitative Perfusion MRI

BACKGROUND

Imaging techniques that quantitatively and automatically measure changes in the myocardial microcirculation in patients with diabetes are lacking.

PURPOSE

To detect diabetic myocardial microvascular complications using a novel automatic quantitative perfusion MRI technique, and to explore the relationship between myocardial microcirculation dysfunction and fibrosis.

STUDY TYPE

Prospective.

SUBJECTS

101 patients with type 2 diabetes mellitus (T2DM) (53 without and 48 with complications), 20 healthy volunteers.

FIELD STRENGTH/SEQUENCE

3.0T; modified Look-Locker inversion-recovery sequence; saturation recovery sequence and dual-bolus technique; segmented fast low-angle shot sequence.

ASSESSMENT

All participants underwent MRI to determine the rest myocardial blood flow (MBF), stress MBF, myocardial perfusion reserve (MPR), and extracellular volume (ECV), which represents the extent of myocardial fibrosis.

STATISTICAL TESTS

Kolmogorov-Smirnov test, Shapiro-Wilk test, Kruskal-Wallis H test, Mann-Whitney U test, chi-square test, Spearman correlation coefficient, multivariable linear regression analysis. P < 0.05 was considered statistically significant.

RESULTS

The rest MBF was not significantly different between the T2DM without complications group (1.1, IQR: 0.9-1.3) and the control group (1.1, 1.0-1.3) (P = 1.000), but it was significantly lower in the T2DM with complications group (0.8, 0.6-1.0) than in both other groups. The stress MBF and MPR were significantly lower in the T2DM without complications group (1.9, 1.5-2.3, and 1.7, 1.4-2.1, respectively) than in the control group (3.0, 2.6-3.5, and 2.7, 2.4-3.1, respectively), and were also significantly lower in the T2DM with complications group (1.1, 0.9-1.4, and 1.4, 1.2-1.8, respectively) than in the T2DM without complications group. A decrease in MBF and MPR were significantly associated with an increase in the ECV.

DATA CONCLUSION

Quantitative perfusion MRI can evaluate myocardial microcirculation dysfunction. In T2DM, there was a significant decrease in both MBF and MPR compared to healthy controls, with the decrease being significantly different between T2DM with and without complications groups. The decrease of MBF was significantly associated with the development of myocardial fibrosis, as determined by ECV.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 3.

Interaction of impaired myocardial flow reserve and extent of myocardial ischemia assessed using 13N-ammonia positron emission tomography imaging on adverse cardiovascular outcomes

BACKGROUND

Myocardial flow reserve (MFR) and the extent of myocardial ischemia identify patients at high risk of major adverse cardiovascular events (MACEs). Associations between positron emission tomography (PET)-assessed extent of ischemia, MFR, and MACEs is unclear.

METHOD

Overall, 640 consecutive patients with suspected or known coronary artery disease undergoing 13N-ammonia myocardial perfusion PET were followed-up for MACEs. Patients were categorized into three groups based on myocardial ischemia severity: Group I (n = 335), minimal (myocardial ischemia < 5%); Group II (n = 150), mild (5-10%); and Group III (n = 155), moderate-to-severe (> 10%).

RESULTS

Cardiovascular death and MACEs occurred in 17 (3%) and 93 (15%) patients, respectively. Following statistical adjustment for confounding factors, impaired MFR (global MFR < 2.0) was revealed as an independent predictor of MACEs in Groups I (hazard ratio [HR], 2.89; 95% confidence interval [CI], 1.48-5.64; P = 0.002) and II (HR, 3.40; 95% CI 1.37-8.41; P = 0.008) but was not significant in Group III (HR, 1.15; 95% CI 0.59-2.26; P = 0.67), with a significant interaction (P < 0.0001) between the extent of myocardial ischemia and MFR.

CONCLUSION

Impaired MFR was significantly associated with increased risk of MACEs in patients with ≤ 10% myocardial ischemia but not with those having > 10% ischemia, allowing a clinically effective risk stratification.

Prognostic value of positron emission tomography derived myocardial flow reserve: A systematic review and meta-analysis

BACKGROUND AND AIMS

Positron Emission Tomography (PET)-derived myocardial flow reserve (MFR) has been shown to have a role in the diagnosis and prognosis of patients with coronary artery disease (CAD). We performed a systematic review and meta-analysis to summarize the body of literature and synthesize the evidence on the prognostic role of PET-derived MFR in patients with known or suspected CAD.

METHODS

A comprehensive literature search of the Medline database from its inception to August 2023, in humans, in any language, was conducted for clinical studies examining the prognostic value of PET imaging in patients of any age, sex, and CAD status. Systematic screening and data extraction of the identified studies were followed by quantitative meta-analysis of PET-MFR's role in predicting adverse clinical events using random effect model. Studies were appraised using the modified Newcastle-Ottawa tool.

RESULTS

A total of 21 studies assessing the prognostic role of PET derived MFR in 46,815 patients with known and/or suspected CAD were included (mean (SD) age 66 (4) years, 48% women). The mean follow-up duration was 36 months (range 10-96). Cardiovascular risk factors were prevalent (73% hypertension, 35% diabetes and 67% dyslipidemia). The definition of the composite outcome varied between studies, with various combinations of mortality, non-fatal myocardial infarction, hospitalization, and coronary revascularization. Pooled impaired MFR was significantly associated with an increased risk of adverse outcomes (RR = 2.94, 95% CI 2.42-3.56, p < 0.001). Results were similar in a subgroup of patients with suspected CAD.

CONCLUSIONS

The available body of evidence shows that impaired PET-derived MFR measured using different tracers and PET systems is strongly associated with an increased risk of adverse cardiovascular events. Limitations of this review include observational nature of studies, marked heterogeneity in patient populations, inconsistency in thresholds to define abnormal MFR, and differing components for the composite outcome.

Prognostic value of coronary CT angiography and CT myocardial perfusion imaging among patients with and without Diabetes

OBJECTIVES

Whether stress CT myocardial perfusion imaging (CT-MPI) improves risk assessment in patients with diabetes mellitus (DM) remains unexplored. We aimed to evaluate the prognostic value of coronary CT angiography (CCTA) and stress CT-MPI in suspected coronary artery disease (CAD) patients with and without DM.

METHODS

A total of 334 patients with suspected CAD who underwent CCTA and stress CT-MPI from May 2020 to July 2021 were retrospectively analyzed. The endpoint was major adverse cardiovascular events (MACEs). Multivariable Cox regression analysis was used to evaluate the risk factors for MACEs, including clinical risk factors, CCTA characteristics and CT-MPI characteristics.

RESULTS

After a median follow-up of 21 months,15 patients of the DM group and 16 patients of the non-DM group experienced MACEs. Multivariate Cox stepwise regression analysis showed that abnormal perfusion myocardial segments ratio was associated with MACEs after adjusting for clinical risk factors and CCTA characteristics in all patients (HR:1.023, p < 0.001), DM group (HR:1.024, p = 0.008) and non-DM group (HR:1.028, p = 0.003). By adding CT-MPI characteristics to CCTA characteristics and clinical risk factors, the global chi-square for predicting MACEs increased from 62.24 to 78.84 in all patients (p < 0.001), from 19.18 to 27.30 in DM group (p = 0.004) and from 39.51 to 48.65 in non-DM group (p = 0.003); the increment of C-index in all patients, DM group and non-DM group were 0.018, 0.054 and 0.019, respectively.

CONCLUSION

In all patients and those with and without DM, CT-MPI has incremental prognostic value over clinical risk factors alone or combined with CCTA characteristics in predicting MACEs.

Impact of Isolated Coronary Microvascular Disease Diagnosed Using Various Measurement Modalities on Prognosis: An Updated Systematic Review and Meta-Analysis

INTRODUCTION

The main aim of this study was to investigate the impact of isolated coronary microvascular disease (CMD) as diagnosed via various modalities on prognosis.

METHODS

A systematic literature review of PubMed, Embase, and Cochrane Library databases was conducted to identify relevant studies published up to March 2023. Included studies were required to measure coronary microvascular function and report outcomes in patients without obstructive coronary artery disease (CAD) or any other cardiac pathological characteristics. The primary endpoint was all-cause mortality, and the secondary endpoint was a major adverse cardiac event (MACE). Pooled effects were calculated using random effects models.

RESULTS

A total of 27 studies comprising 18,204 subjects were included in the meta-analysis. Indices of coronary microvascular function measurement included coronary angiography-derived index of microcirculatory resistance (caIMR), hyperemic microcirculatory resistance (HMR), coronary flow reserve (CFR), and so on. Patients with isolated CMD exhibited a significantly higher risk of mortality (OR: 2.97, 95% CI, 1.91-4.60, p < 0.0001; HR: 3.38, 95% CI, 1.77-6.47, p = 0.0002) and MACE (OR: 5.82, 95% CI, 3.65-9.29, p < 0.00001; HR: 4.01, 95% CI, 2.59-6.20, p < 0.00001) compared to those without CMD. Subgroup analysis by measurement modality demonstrated consistent and robust pooled effect estimates in various subgroups.

CONCLUSION

CMD is significantly associated with an elevated risk of mortality and MACE in patients without obstructive CAD or any other identifiable cardiac pathologies. The utilization of various measurement techniques may have potential advantages in the management of isolated CMD.

Myocardial blood flow evaluation with dynamic cadmium-zinc-telluride single-photon emission computed tomography: Bright and dark sides

Myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) assessment with non-invasive techniques represent an important tool to evaluate both coronary artery disease severity and extent. Currently, cardiac positron emission tomography-computed tomography (PET-CT) is the "gold standard" for the assessment of coronary function and provides accurate estimations of baseline and hyperemic MBF and MFR. Nevertheless, due to the high cost and complexity, PET-CT is not widely used in clinical practice. The introduction of cardiac-dedicated cadmium-zinc-telluride (CZT) cameras has renewed researchers' interest on MBF quantitation by single-photon emission computed tomography (SPECT). Indeed, many studies evaluated MPR and MBF measurements by dynamic CZT-SPECT in different cohorts of patients with suspected or overt coronary artery disease. As well, many others have compared the values obtained by CZT-SPECT to the ones by PET-CT, showing good correlations in detecting significant stenosis, although with different and non-standardized cut-off values. Nevertheless, the lack of standardized protocol for acquisition, reconstruction and elaboration makes more difficult to compare different studies and to further assess the real advantages of MBF quantitation by dynamic CZT-SPECT in clinical routine. Many are the issues involved in the bright and dark sides of dynamic CZT-SPECT. They include different type of CZT cameras, different execution protocols, different tracers with different myocardial extraction fraction and distribution, different software packages with different tools and algorithms, often requiring manual post-processing elaboration. This review article provides a clear summary of the state of the art on MBF and MPR evaluation by dynamic CZT-SPECT and outlines the major issues to solve to optimize this technique.

Prediction of outcome by 82Rb PET/CT in patients with ischemia and nonobstructive coronary arteries

BACKGROUND

The purpose of this study was to assess the prognostic value of cardiac 82Rb positron emission tomography (PET)/computed tomography (CT) imaging in patients with myocardial ischemia of nonobstructive coronary arteries (INOCA).

METHODS

We retrospectively evaluated 311 INOCA patients who underwent rest stress 82Rb PET/CT. Cardiac end points were cardiac death, myocardial infarction, or late coronary revascularization. A parametric survival model was also used to identify how the variables influenced time to event.

RESULTS

During a median follow-up of 37 months (range 6-108), 23 (7%) cardiac events occurred. In patients with events total perfusion defect (TPD) was higher and myocardial flow reserve (MFR) lower compared to those without events (both P < .001). At multivariable Cox analysis, increased TPD (i.e., ≥ 5%) and reduced MFR (i.e., < 2) were predictors of events (both P < .001). At Weibull survival analysis, the highest probability of cardiac events and risk acceleration were observed in patients with both increased TPD and reduced MFR. Annualized event rate was higher in patients with reduced MFR compared to those with preserved MFR (P < .001).

CONCLUSION

In patients with INOCA, the combined evaluation of myocardial perfusion and coronary vascular function by 82Rb PET/CT is able to identify those at higher risk of cardiac events.

The impact of diabetes on the relationship of coronary artery disease and outcome: a study using multimodality imaging

BACKGROUND

Patients with prediabetes or diabetes are at increased risk of developing cardiovascular disease and adverse outcomes. First-line coronary computed tomography angiography (CTA) followed by selective use of positron emission tomography (PET) myocardial perfusion imaging is a feasible strategy to diagnose and risk-stratify patients with suspected coronary artery disease (CAD). The aim of the present study was to study whether diabetes changes the relationship of CAD and long-term outcome.

METHODS

We retrospectively identified consecutive symptomatic patients who underwent coronary CTA for suspected CAD. In patients with suspected obstructive CAD on CTA, myocardial ischemia was evaluated by ¹⁵O-water PET myocardial perfusion imaging. The relationship of the phenotype of CAD and long-term outcome in patients with no diabetes, prediabetes, or type 2 diabetes was investigated. A composite endpoint included all-cause mortality, myocardial infarction (MI), and unstable angina pectoris (UAP).

RESULTS

A total of 1743 patients were included: 1214 (70%) non-diabetic, 259 (15%) prediabetic, and 270 (16%) type 2 diabetic patients. During 6.43 years of median follow-up, 164 adverse events occurred (106 deaths, 41 MIs, 17 UAPs). The prevalence of normal coronary arteries on CTA was highest in the non-diabetic patients (39%). The prevalence of hemodynamically significant CAD (abnormal perfusion) increased from 14% in non-diabetic patients to 20% in prediabetic and 27% in diabetic patients. The event rate was lowest in patients with normal coronary arteries and highest in patients with concomitant type 2 diabetes and hemodynamically significant CAD (annual event rate 0.2% vs. 4.7%). However, neither prediabetes nor diabetes were independent predictors of the composite adverse outcome after adjustment for the clinical risk factors and imaging findings.

CONCLUSIONS

Coronary CTA followed by selective downstream use of PET myocardial perfusion imaging predicts long-term outcome similarly in non-diabetic and diabetic patients.

The Role of Cardiac PET in Diagnosis and Prognosis of Ischemic Heart Disease: Optimal Modality Across Different Patient Populations

PURPOSE OF REVIEW

Despite single-photon emission computerized tomography (SPECT) being the most used nuclear imaging technique for diagnosis of coronary artery disease (CAD), many now consider positron emission tomography (PET) as a superior modality. This review will focus on the advances of cardiac PET in recent years and its advantages compared to SPECT in diagnosis and prognosis of CAD.

RECENT FINDINGS

PET's higher resolution and enhanced diagnostic accuracy, as well as lower radiation exposure, all help explain the rationale for its wider spread and use. PET also allows for measurement of myocardial blood flow (MBF) and myocardial flow reserve (MFR), which aids in several different clinical scenarios, such as diagnosing multivessel disease or identifying non-responders. PET has also been shown to be useful in diagnosing CAD in various specific populations, such as patients with prior COVID-19 infection, cardiac transplant, and other comorbidities.

Computed tomography and nuclear medicine for the assessment of coronary inflammation: clinical applications and perspectives

There is increasing evidence that in patients with atherosclerotic cardiovascular disease (ASCVD) under optimal medical therapy, a persisting dysregulation of the lipid and glucose metabolism, associated with adipose tissue dysfunction and inflammation, predicts a substantial residual risk of disease progression and cardiovascular events. Despite the inflammatory nature of ASCVD, circulating biomarkers such as high-sensitivity C-reactive protein and interleukins may lack specificity for vascular inflammation. As known, dysfunctional epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT) produce pro-inflammatory mediators and promote cellular tissue infiltration triggering further pro-inflammatory mechanisms. The consequent tissue modifications determine the attenuation of PCAT as assessed and measured by coronary computed tomography angiography (CCTA). Recently, relevant studies have demonstrated a correlation between EAT and PCAT and obstructive coronary artery disease, inflammatory plaque status and coronary flow reserve (CFR). In parallel, CFR is well recognized as a marker of coronary vasomotor function that incorporates the haemodynamic effects of epicardial, diffuse and small-vessel disease on myocardial tissue perfusion. An inverse relationship between EAT volume and coronary vascular function and the association of PCAT attenuation and impaired CFR have already been reported. Moreover, many studies demonstrated that 18F-FDG PET is able to detect PCAT inflammation in patients with coronary atherosclerosis. Importantly, the perivascular FAI (fat attenuation index) showed incremental value for the prediction of adverse clinical events beyond traditional risk factors and CCTA indices by providing a quantitative measure of coronary inflammation. As an indicator of increased cardiac mortality, it could guide early targeted primary prevention in a wide spectrum of patients. In this review, we summarize the current evidence regarding the clinical applications and perspectives of EAT and PCAT assessment performed by CCTA and the prognostic information derived by nuclear medicine.

Low Quantitative Blush Evaluator score predicts larger infarct size and reduced left ventricular systolic function in patients with STEMI regardless of diabetes status

Type 2 diabetes mellitus (T2DM) and diminished myocardial perfusion increase the risk of heart failure (HF) and/or all-cause mortality during 6-year follow up following primary percutaneous coronary intervention (pPCI) for ST elevation myocardial infarction (STEMI). The aim of the present study was to evaluate the impact of myocardial perfusion on infarct size and left ventricular ejection fraction (LVEF) in patients with T2DM and STEMI treated with pPCI. This is an ancillary analysis of an observational cohort study of T2DM patients with STEMI. We enrolled 406 patients with STEMI, including 104 with T2DM. Myocardial perfusion was assessed with the Quantitative Myocardial Blush Evaluator (QUBE) and infarct size with the creatine kinase myocardial band (CK-MB) maximal activity and troponin area under the curve. LVEF was measured with biplane echocardiography using Simpson's method at admission and hospital discharge. Analysis of covariance was used for modeling the association between myocardial perfusion, infarct size and left ventricular systolic function. Patients with T2DM and diminished perfusion (QUBE below median) had the highest CK-MB maximal activity (252.7 ± 307.2 IU/L, P < 0.01) along with the lowest LVEF (40.6 ± 10.0, P < 0.001). Older age (p = 0.001), QuBE below median (p = 0.026), and maximal CK-MB activity (p < 0.001) were independent predictors of LVEF. Diminished myocardial perfusion assessed by QuBE predicts significantly larger enzymatic infarct size and lower LVEF among patients with STEMI treated with pPCI, regardless of diabetes status.

Atherosclerosis Burdens in Diabetes Mellitus: Assessment by PET Imaging

Arteriosclerosis and its sequelae are the most common cause of death in diabetic patients and one of the reasons why diabetes has entered the top 10 causes of death worldwide, fatalities having doubled since 2000. The literature in the field claims almost unanimously that arteriosclerosis is more frequent or develops more rapidly in diabetic than non-diabetic subjects, and that the disease is caused by arterial inflammation, the control of which should therefore be the goal of therapeutic efforts. These views are mostly based on indirect methodologies, including studies of artery wall thickness or stiffness, or on conventional CT-based imaging used to demonstrate tissue changes occurring late in the disease process. In contrast, imaging with positron emission tomography and computed tomography (PET/CT) applying the tracers 18F-fluorodeoxyglucose (FDG) or 18F-sodium fluoride (NaF) mirrors arterial wall inflammation and microcalcification, respectively, early in the course of the disease, potentially enabling in vivo insight into molecular processes. The present review provides an overview of the literature from the more than 20 and 10 years, respectively, that these two tracers have been used for the study of atherosclerosis, with emphasis on what new information they have provided in relation to diabetes and which questions remain insufficiently elucidated.

Combining flow and reserve measurement during myocardial perfusion imaging: A new era for myocardial perfusion scintigraphy?

Myocardial flow reserve represents the ratio of myocardial blood flow between stress and rest, giving functional information about both macrocirculation and microcirculation; it has been reported extensively in positron emission tomography, with an increase in diagnostic performance, providing important prognostic information and being a powerful tool to guide therapy. Advances in single photon emission computed tomography, with the widespread availability of "cadmium zinc telluride" single photon emission computed tomography cameras, raise the question of myocardial flow reserve use in daily clinical practice. In this article, we review the pathophysiology of myocardial blood flow and myocardial flow reserve, and the initial data available from single photon emission computed tomography myocardial blood flow and myocardial flow reserve evaluation; we also discuss potential limitations to the wider implementation of flow evaluation in single photon emission computed tomography.

Comparing left ventricular mechanical dyssynchrony between diabetic and non-diabetic patients with normal gated SPECT MPI

The aim of this study was to employ phase analysis to diagnose left ventricular mechanical dyssynchrony (LVMD) in asymptomatic patients with diabetes mellitus type 2 and normal perfusion study which may help prevent diabetic cardiomyopathy. Ninety-three consecutive patients with known type 2 diabetes and 81 age- and gender- matched patients without diabetes who were candidates for SPECT-MPI were considered as the control group. The presence of LVMD as an possible risk factor for cardiomyopathy- was determined using phase analysis for each scan with quantitative gated SPECT (QGS) and corridor4DM (4DM) software. All outcomes such as phase bandwidth (PBW) and phase standard deviation (PSD) were compared between the two groups. A total of 174 patients were included in the study. There were no statistically significant difference regarding demographic factors between the two groups (P > 0.05). PBW showed statistically significant differences (increased in diabetics) between the control and diabetic patients (P < 0.05). Kruskal Wallis analysis revealed that as the duration of diabetes is prolonged, especially more than 15 years, the probability of LVMD is increased as well (P = 0.021). Fraction of asymptomatic diabetic patients with normal ejection fraction and gated SPECT MPI-especially those with prolonged diabetes- might have some degrees of LVMD. Phase analysis can detect this which in turn may prevent progress into heart failure.