The significance of transient ischemic dilation in the setting of otherwise normal SPECT radionuclide myocardial perfusion images

Relationship between transient ischemic dilatation and changes in heart rate during gated SPECT acquisition in a low-risk population without perfusion defects

OBJECTIVES

Transient ischemic dilatation (TID) in myocardial perfusion single photon emission computed tomography (SPECT) is considered a marker of poor prognosis. However, it has been suggested that some cases are due to apparent volumetric changes secondary to differences in heart rate (HR) at the time of acquisition. We assessed the correlation between transient dilatation and HR in low risk patients with no perfusion defects.

METHODS

We retrospectively analyzed patients sent for 99mTc-MIBI SPECT using a 2-day protocol. We recorded the median HR during acquisition and the HR difference (HRD) between the rest and post-stress. We obtained the medium ventricular volume, end-diastolic volume (EDV), and end-systolic volume (ESV). We included patients in which TID using medium ventricular volume (TIDMV) was ≥1.2. TID was also calculated for the EDV and ESV (TIDEDV, TIDESV). We excluded patients with known coronary artery disease, perfusion defects, various ECG disorders, positive stress test, or ESV < 10 ml.

RESULTS

From a total of 2006 patients, 63 (50 exercise, 13 dipyridamole) met the criteria for analysis (age 63.8 ± 9.7, 44 men). TIDMV was 1.29 ± 0.09 and HRD 9.8 beats per minute (BPM) (range -10 to 41). There was positive correlation between HRD and TIDMV ( r  = 0.51, P  < 0.001) and TIDEDV ( r  = 0.5, P  < 0.001), but not TIDESV ( r  = 0.23, P  = 0.07). Correlation was stronger when HRD was ≥10 BPM ( r  = 0.67, P  < 0.001).

CONCLUSION

TID without perfusion defects should be interpreted with caution in the presence of HRD ≥ 10 BPM during post-stress acquisition.

Clinical phenotypes among patients with normal cardiac perfusion using unsupervised learning: a retrospective observational study

BACKGROUND

Myocardial perfusion imaging (MPI) is one of the most common cardiac scans and is used for diagnosis of coronary artery disease and assessment of cardiovascular risk. However, the large majority of MPI patients have normal results. We evaluated whether unsupervised machine learning could identify unique phenotypes among patients with normal scans and whether those phenotypes were associated with risk of death or myocardial infarction.

METHODS

Patients from a large international multicenter MPI registry (10 sites) with normal perfusion by expert visual interpretation were included in this cohort analysis. The training population included 9849 patients, and external testing population 12,528 patients. Unsupervised cluster analysis was performed, with separate training and external testing cohorts, to identify clusters, with four distinct phenotypes. We evaluated the clinical and imaging features of clusters and their associations with death or myocardial infarction.

FINDINGS

Patients in Clusters 1 and 2 almost exclusively underwent exercise stress, while patients in Clusters 3 and 4 mostly required pharmacologic stress. In external testing, the risk for Cluster 4 patients (20.2% of population, unadjusted hazard ratio [HR] 6.17, 95% confidence interval [CI] 4.64-8.20) was higher than the risk associated with pharmacologic stress (HR 3.03, 95% CI 2.53-3.63), or previous myocardial infarction (HR 1.82, 95% CI 1.40-2.36).

INTERPRETATION

Unsupervised learning identified four distinct phenotypes of patients with normal perfusion scans, with a significant proportion of patients at very high risk of myocardial infarction or death. Our results suggest a potential role for patient phenotyping to improve risk stratification of patients with normal imaging results.

FUNDING

This work was supported by the National Heart, Lung, and Blood Institute at the National Institutes of Health [R35HL161195 to PS]. The REFINE SPECT database was supported by the National Heart, Lung, and Blood Institute at the National Institutes of Health [R01HL089765 to PS]. MCW was supported by the British Heart Foundation [FS/ICRF/20/26002].

The Impact of Left Ventricle Ejection Fraction Reduction and Transient Ischemic Dilation in Patients With Normal Single-Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging

INTRODUCTION

Coronary artery disease (CAD) is a leading cause of death in developed countries. Non-invasive functional imaging modalities are currently recommended as initial diagnostic tests in patients with an intermediate-high pretest probability of CAD. Single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) creates images of regional myocardial tracer uptake, reflecting relative myocardial blood flow. However, there are other non-perfusion predictors of CAD, such as transient ischemic dilatation (TID) and reduced post-stress left ventricle ejection fraction (LVEF). Available data regarding these parameters is controversial. The aim of our study was to evaluate the incidence of significant CAD in patients with non-perfusion high-risk markers of ischemia despite a normal SPECT-MPI.

METHODS

Single-center, observational, retrospective, and longitudinal study. Inclusion criteria were age ≥18 years, normal SPECT-MPI, and availability of gated study for LVEF and volume analysis. Exclusion criteria were any known cardiomyopathy or congenital heart disease and known CAD. Non-perfusion high-risk markers: LVEF reduction ≥5% on post-stress images; TID (defined as a stress/rest left ventricle volume ratio ≥ 1.15), including end-systolic, end-diastolic, and mean volumes. The primary endpoint was the identification of significant CAD (stenosis >70% on an epicardial coronary artery or >50% on the left main artery) on invasive coronary angiography.

RESULTS

A total of 197 patients met the inclusion criteria. Mean age was 64 ± 12.6 years and 59.4% (n = 117) of patients were male. Overall, 26% of patients had LVEF reduction ≥5% on stress study; 24.9% had a stress/rest end-systolic volume ratio ≥ 1.15; 7.1% had a stress/rest mean volume ratio ≥ 1.15; 7.1% had a stress/rest end-diastolic volume ratio ≥ 1.15. Time-to-primary endpoint was significantly lower in patients with LVEF reduction ≥5% on stress study (67.99 (95% CI 60.49-75.49) vs. 77.56 months (95% CI 75.14-79.99); p = 0.003) and in patients with stress/rest end-systolic volume ratio ≥ 1.15 (68.39 (95% CI 60.69-76.10) vs. 77.31 months (95% ICCI 74.68-79.76); p = 0.013).

CONCLUSION

In patients with normal perfusion on SPECT-MPI, the incidence of significant CAD was significantly higher in those with LVEF reduction ≥ 5% on stress study and in those with a stress/rest end-systolic volume ratio ≥ 1.15, during a follow-up period of five years.

Transient ischemic dilation or transient RV visualization in patients with normal SPECT stress myocardial perfusion imaging: Correlation with CT coronary artery calcium scoring and coronary angiography

BACKGROUND

Ancillary findings on MPI, such as transient ischemic dilation (TID) and transient right ventricular visualization (TRV), are recognized as markers of extensive CAD and predictive of adverse outcomes. They usually occur in association with stress-induced regional MPI abnormalities. However, the clinical significance of these ancillary markers in the presence of normal stress MPI is incompletely understood.

METHODS

From a cohort of 564 consecutive patients referred for clinical SPECT stress MPI, 44 patients had normal stress SPECT MPI and either TID (n = 28) or TRV (n = 16). These imaging findings were correlated with CT coronary calcium (CAC), CT coronary angiography (CTA), and invasive coronary angiography (ICA) in patients with severe CAC ≥ 1000 HU. TID and TRV were quantified as stress/rest ratios. Severe CAD was defined as > 70% luminal stenosis on CTA or ICA.

RESULTS

The median TID ratio was 1.23, with a range of 1.13-1.48; the median TRV ratio was 1.30, with a range of 1.20-1.48. Of 44 patients with TID or TRV, only 9 patients (20.5%) had severe obstructive > 70% CAD by angiography (6 of 28 patients (21.5%) with TID and 3 of 16 patients (19%) with TRV). Severe multi-vessel CAD occurred in only 2 of 44 patients (4.5%). In contrast, of 9 patients with CAC > 1000 HU, 6 (67%) had severe obstructive CAD.

CONCLUSION

In patients with normal stress SPECT MPI and TID or TRV, the incidence of severe obstructive CAD was relatively low and predominantly single-vessel CAD. These findings do not support the concept that TID or TRV with normal stress MPI is predictive of high-risk CAD.

Implications of transient ischemic dilatation and impaired left ventricular ejection fraction reserve in patients with normal stress myocardial perfusion imaging and elevated coronary artery calcium

PURPOSE

Guidelines recommend stress only (SO) myocardial perfusion imaging (MPI) without follow-up rest imaging if perfusion and left ventricular ejection fraction (LVEF) are normal. However additional rest imaging may show transient ischaemic dilation (TID) and/or impaired LVEF reserve (iLVEFr) suggestive of 'balanced ischemia'. Concurrent coronary artery calcium (CAC) scoring helps to identify subclinical atherosclerosis. The safety of SO MPI when CAC is elevated is unclear. We aim to assess the incidence and outcomes of TID and iLVEFr amongst stress/rest MPIs with normal SO images and elevated CAC.

METHODS

Retrospective analysis of normal stress/rest MPIs performed between 1 March 2016 to 31 January 2017 with concurrently measured CAC >300. Cases were stratified by presence of TID and/or iLVEFr. Major adverse cardiac events (MACE, defined as cardiac death, non-fatal myocardial infarction and revascularization) within 24 months were compared.

RESULTS

There were 230 cases included of which 43 (18.7%) had TID and/or iLVEFr. Presence of TID and/or iLVEFr was associated with higher 24-month MACE (23.3 vs. 8.6%, p = 0.013), driven by more elective revascularizations (18.6 vs. 4.3%, p = 0.001). Cardiac death and non-fatal myocardial infarction rates were similar. TID and/or iLVEFr significantly predicted overall MACE after multivariate analysis (OR 2.933 [1.214 - 7.087], p = 0.017).

CONCLUSIONS

TID and/or iLVEFr is seen in the minority of normal stress MPI with elevated CAC, and is associated with higher 24-month MACE, driven by higher elective revascularizations. Overall cardiac death and non-fatal myocardial infarction rates were low and not significantly different between both groups.

Transient ischemic dilatation with adenosine 99mTc-sestamibi stress: prognostic significance in patients with normal myocardial perfusion

OBJECTIVE

To determine the significance of transient ischemic dilatation (TID) in patients with normal perfusion on adenosine stress/rest.

METHODS

We analyzed 430 consecutive patients with normal perfusion on 2-day adenosine stress/rest 99mTc-sestamibi. A group of 70 patients with Framingham 10-year coronary heart disease risk < 10% was used to derive abnormal TID thresholds (derivation group). The significance of TID at these thresholds was validated in the remaining 360 patients (validation group) followed for cardiac events for 31.2 ± 9.7 (mean ± SD) months.

RESULTS

Transient ischemic dilatation in the derivation group was 1.05 ± 0.13. Three definitions of an abnormal TID were used: > mean + 2SD (TID ≥ 1.32), > mean + 1SD (TID ≥ 1.19) and a TID in the group's highest quartile (TID ≥ 1.15). Of the 360 validation group patients, 12 (3.3%), 48 (13.3%) and 70 (19.4%) had TID ≥ 1.32, 1.19 and 1.15, respectively. Age, gender, family history of coronary artery disease (CAD), known CAD, smoking, hypertension, diabetes, dyslipidemia, rest LVEF, post-stress LVEF, ΔLVEF, ≥ 5% or 10% decrease in LVEF did not predict TID ≥ 1.32. However, TID ≥ 1.19 was predicted by rest LVEF and ≥ 5% decrease in LVEF (P = 0.04 and 0.02, respectively) and TID ≥ 1.15 was predicted by ≥ 5% decrease in LVEF (P = 0.02). Cardiac event-free survivals were similar in patients with a TID ≥ and < 1.32 (P = 0.68), ≥ and < 1.19 (P = 0.40) and ≥ and < 1.15 (P = 0.79).

CONCLUSIONS

Transient ischemic dilatation does not confer adverse prognosis in patients with normal perfusion on adenosine stress/rest 99mTc-sestamibi irrespective of the threshold used for its definition.

Coronary microvascular dysfunction: An important interpretation on the clinical significance of transient ischemic dilation of the left ventricle on myocardial perfusion imaging

PURPOSE

To further investigate the clinical significance of transient ischemic dilation (TID) on myocardial perfusion imaging (MPI) by analyzing the effect of anisodamine hydrobromide (a drug that can effectively ameliorate microcirculation) on the patients with isolated TID and the findings of previous literatures.

METHODS

Total 107 patients with isolated TID (TID value≥1.11) were randomly divided into group A (n = 36; intravenous administration of anisodamine hydrobromide), group N (n = 36; intravenous administration of isosorbide dinitrate), and group C (n = 35; intravenous administration of normal saline). MPI and treadmill exercise test (TET) were performed again after 14-day course of intervention. Pre- and post-intervention frequencies of symptom were recorded.

RESULTS

In group A, after intervention of anisodamine hydrobromide, the summed stress score (SSS) and TID value on MPI significantly decreased than those before intervention (P < 0.001), the durations of exercise (DEs) and metabolic equivalents (METs) in TET notably ascended (P < 0.001), as well as the symptom remarkably improved. In group N and group C, there were no significant differences in SSS, TID value, DEs, METs, and frequencies of symptom between pre- and post-intervention (P > 0.05). No significant improvement of symptoms in group N before and after treatment.

CONCLUSIONS

TID with perfusion defect may usually predict a possibility of severe and extensive coronary artery disease (CAD). An isolated TID should be considered as a likelihood of coronary microvascular dysfunction (CMD). TET and coronary CT angiography (cCTA) are extremely helpful for the antidiastole on CAD and CMD. The administration of anisodamine hydrobromide might be an optional treatment for the patients with isolated TID.

CRAX: A simple cardiovascular risk assessment tool to predict risk of acute myocardial infarction or death

BACKGROUND

Determining the risk of cardiovascular events is essential to optimize patient management.

METHODS AND RESULTS

5842 individuals underwent SPECT myocardial perfusion imaging (MPI) with 4.4 ± 1.2 years of follow-up. Models (the CRAX tool) were derived to predict the cumulative risk of death and acute myocardial infarction (AMI) at 1, 3, and 5 years using clinical and MPI variables. Predictors of AMI and death included age, number of hospitalizations in the 3 years preceding MPI, and left ventricular ejection fraction (LVEF). Additional predictors of death were the use of pharmacological stress, and global stress total perfusion deficit (sTPD), while transient ischemic dilation (TID), and ischemic total perfusion deficit (iTPD) change were predictive of AMI. CRAX predictions were significantly (P < .001) more accurate than clinical variables or MPI results alone, resulting in a significant net reclassification improvement (NRI, 7.5% for AMI, 14.5% death) compared to clinical variables alone. Accuracy for predicting major adverse cardiac events (MACE, comprising all-cause death, AMI, unstable angina, late revascularization) was comparable to that of AMI or death.

CONCLUSIONS

CRAX is a risk assessment tool that predicts the risk of AMI, death, or MACE, and improves prediction compared to clinical variables or MPI results alone.

How variable are the volumetric measurements from gated perfusion SPECT when a one-day stress-rest protocol is used?

BACKGROUND

Using myocardial perfusion scintigraphy (MPS), an increase in left ventricular (LV) volumes or a decrease in ejection fraction (EF) from rest to stress may be clinically important. The variation in these measures between the low-dose stress acquisition and high-dose rest acquisition in a one-day stress-rest protocol has not been established. We assessed the reproducibility of gated volumetric indices between stress and rest and the normal variation in ungated TID ratio for a one-day stress-rest 99mTc-tetrofosmin protocol.

METHODS

Two thousand and one hundred and fifty eight (2158) 99mTc-tetrofosmin MPS patient studies were analyzed retrospectively. Studies were excluded for incomplete data, significant technical difficulties, or (for gated analysis but not for analysis of TID ratio) if the LV EF was > 75%. An analysis of gated data was undertaken to establish the reproducibility of ventricular volumes and EF between stress and rest scans. Ungated volume data were analyzed to determine the confidence limits of TID ratio according to ventricular volume.

RESULTS

Gated data were analyzed for 621 patients without inducible hypoperfusion. Mean EF at rest was slightly higher than after stress (62.4% ± 10.3% vs 61.2% ± 10.4%, P < 0.001), and the standard deviation of the difference was 5.2% (95% CI 4.9% to 5.5%). Ungated volumes were available for 992 non-ischaemic patients. The upper 95% CI for TID ratio was 1.23. This increased from 1.20 to 1.37 between the highest and lowest deciles of rest ungated volume.

CONCLUSION

Using a one-day stress-rest 99mTc-tetrofosmin protocol, a fall in LV EF between rest and stress of > 11.6% or a TID ratio of > 1.23 is likely to be clinically reliable. The upper limit of normal for TID ratio needs to be increased for patients with small LV chamber volumes.

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.

Prognostic value of transient ischemic dilation with regadenoson myocardial perfusion imaging

BACKGROUND

Transient ischemic dilation (TID) of the left ventricle seen on myocardial perfusion imaging (MPI) is sometimes used as a marker of severe coronary artery disease. The prognostic value of TID obtained using regadenoson, a selective adenosine A2A receptor agonist, as a stress agent for MPI has not been studied.

METHODS

TID ratio was measured using an automated software program on consecutive patients with normal and abnormal perfusion pattern on regadenoson MPI at a single institution. An abnormal TID was defined as greater than 1.33. The primary outcome was a composite of cardiac death, non-fatal myocardial infarction (MI), and late coronary revascularization (CR, >90 days after MPI).

RESULTS

The study population consisted of 887 patients (62 ± 12 years, 66% male, 48% diabetes, 46% prior CR, 75% with abnormal perfusion pattern, left ventricular ejection fraction-LVEF 55 ± 6%). An abnormal TID was present in 51 (6%) patients. Baseline characteristics were not different based on the presence or absence of TID. Early CR (≤90 days) was performed in 11 (22%) patients with vs 92 (11%) patients without TID (P = .04). During a mean follow-up of 29 ± 19 months, the primary outcome occurred in 271 (31%) patients (22% cardiac death, 6% MI, 9% late CR). TID was associated with increased risk of the primary outcome (log-rank P = .017), an association largely driven by late CR. In a Cox proportional model adjusted for multiple variables including perfusion defect size (PDS) and LVEF, the hazard ratio for TID was 1.92 (95% CI 1.20-3.08, P = .007). In the subset of patients with normal perfusion pattern, there was no association between TID and outcomes.

CONCLUSIONS

TID on regadenoson MPI carries important prognostic information that is independent from PDS and LVEF, but this association is restricted to patients with abnormal perfusion on imaging.

Predictors of high-risk coronary artery disease in subjects with normal SPECT myocardial perfusion imaging

BACKGROUND

While uncommon, normal stress SPECT myocardial perfusion imaging (MPI) can be seen in patients with high-risk coronary artery disease (CAD) by invasive coronary angiography (ICA).The predictors of high-risk CAD in patients with normal SPECT-MPI have not been described.

METHODS

We studied 580 patients (age 64 ± 12 years, 49% men) without known CAD who underwent stress-gated SPECT-MPI [exercise (41%) or vasodilator (59%)] <2 months before ICA and had summed stress score (SSS) <4. High-risk CAD was defined as 3 vessels with ≥70% stenosis, 2 vessels with ≥70% stenosis including proximal left anterior descending, or left main with ≥50% stenosis. Obstructive non-high-risk CAD was defined by the presence of a ≥70% stenosis but without having other high-risk criteria. Tenfold cross-validated receiver operating characteristic (ROC) estimates were obtained to assess the predictors of high-risk CAD.

RESULTS

Forty-two subjects (7.2%) had high-risk CAD and 168 (29.0%) had obstructive non-high-risk CAD. Variables associated with high-risk CAD were pretest probability of CAD ≥66% (Odds ratio [OR] 3.63, 95% CI 1.6-8.3, P = .002), SSS > 0 (OR 7.46, 95% CI 2.6-21.1, P < 0.001), and abnormal TID (OR 2.16, 95% CI 1.0-4.5, P = 0.044). When substituted for TID, EF change was also predictive of high-risk CAD (OR 0.93, 95% CI 0.9-1.0, P = 0.023). The prevalence of high-risk CAD increased as the number of these predictors increased. In a sub-analysis of patients in whom quantitative total perfusion deficit (TPD) was available, TPD > 0 was also a predictor of high-risk CAD (OR 6.01, 95% CI 1.5-22.2, P = 0.011).

CONCLUSION

Several clinical, stress, and SPECT-MPI findings are associated high-risk CAD among patients with normal SPECT-MPI. Consideration of these factors may improve the overall assessment of the likelihood of high-risk CAD in patients undergoing stress SPECT-MPI.

The prognostic value of non-perfusion variables obtained during vasodilator stress myocardial perfusion imaging

Myocardial perfusion imaging (MPI) is an established diagnostic test that provides useful prognostic data in patients with known or suspected coronary artery disease. In more than half of the patients referred for stress testing, vasodilator stress is used in lieu of exercise. Unlike exercise, vasodilator stress does not provide information on exercise and functional capacity, heart rate recovery, and chronotropy, and ECG changes are less frequent. These non-perfusion data provide important prognostic and patient management information. Further, event rates in patients undergoing vasodilator MPI are higher than in those undergoing exercise MPI and even in those with normal images probably due to higher pretest risk. However, there are a number of non-perfusion variables that are obtained during vasodilator stress testing, which have prognostic relevance but their use has not been well emphasized. The purpose of this review is to summarize the prognostic values of these non-perfusion data obtained during vasodilator MPI.

Very high coronary artery calcium score with normal myocardial perfusion SPECT imaging is associated with a moderate incidence of severe coronary artery disease

PURPOSE

Myocardial perfusion imaging (MPI) has limitations in the presence of balanced multivessel disease (MVD) and left main (LM) coronary artery disease, occasionally resulting in false-normal results despite the high cardiovascular risk associated with this condition. The purpose of this study was to assess the incidence of severe coronary artery disease (CAD) in the presence of a very high Agatston coronary artery calcium (CAC) score (>1,000) in stable symptomatic patients without known CAD but with normal MPI results.

METHODS

A total of 2,659 prospectively acquired consecutive patients were referred for MPI and evaluation of CAC score by CT. Of this patient population, 8 % (222/2,659) had ischemia without myocardial infarction (MI) on MPIand 11 % (298/2,659) had abnormal MPI (MI and/or ischemia). On presentation 1 % of the patients (26/2,659) were symptomatic, had a CAC score >1,000 and normal MPI results. The definition of normal MPI was strict and included a normal hemodynamic response without ischemic ECG changes and normal imaging, particularly absence of transient ischemic dilation. All of these 26 patients with a CAC score >1,000 and normal MPI findings underwent cardiac catheterization.

RESULTS

Of these 26 patients, 58 % (15/26) had severe disease (≥70 % stenosis) leading to revascularization. Of this group, 47 % (7/15) underwent percutaneous intervention, and 53 % (8/15) underwent coronary artery bypass grafting. All of these 15 patients had either MVD (14/15) or LM coronary artery disease (1/15), and represented 0.6 % (15/2,659) of all referred patients (95 % CI 0.3 - 0.9 %). The majority, 90 % (8/9), had severe CAD with typical chest pain.

CONCLUSION

A very high CAC score (>1,000) with normal MPI in a small subset of symptomatically stable patients was associated with a moderate incidence of severe CAD (95 % CI 37 - 77 %). Larger studies and/or a meta-analysis of small studies are needed to more precisely estimate the incidence of CAD in this population. This study also supports the concept that a normal MPI result in patients with severe CAD may be due to balanced MVD.

Normal Myocardial Perfusion Gated SPECT and Positive Stress Test: Different Prognoses in Women and Men

BACKGROUND

The aim of this study was to analyze different prognoses in women and men with normal myocardial perfusion gated SPECT, according to stress test results.

METHODS

Differences between women and men in terms of hard events (HE) (non-fatal acute myocardial infarction or cardiac death) and HE plus coronary revascularization (HE + CR) were analyzed in 2,414 consecutive patients (mean age 62.8 ± 13.5 years, 1,438 women) with a normal stress-rest gated SPECT, taking into account their stress test results.

RESULTS

Four hundred and seven patients (16.9%) (15.9% women and 17.5% men) had a positive stress test (ST-segment depression ≥1 mm and/or angina). During a follow-up of 5.1 ± 3.4 years, there were more significant HE (6.5% vs 2.3%; P = .005) and HE + CR (11.6% vs 4.8%, P = .001) in men with a positive stress test than in men with a negative stress test. These differences were not observed in women. In multivariate regression models, HE and HE + CR were also more frequent in men with a positive stress test (HR:3.3 [95% CI 1.1% to 9.5%]; HR:4.2 [95% CI 1.8% to 9.9%]; respectively) vs women with a positive stress test.

CONCLUSIONS

Although patients with normal gated SPECT studies have a favorable outcome, men with an abnormal stress test have a more adverse prognosis than women.

Transient Ischemic Dilation in Patients With Diabetes Mellitus

Background—

We prospectively evaluated the incremental prognostic value of transient ischemic dilation (TID) in patients with type 2 diabetes mellitus during long-term follow-up and estimated cardiac death and nonfatal myocardial infarction (MI) using traditional approaches of prognostication to more recent methods.

Methods and Results—

A total of 672 consecutive diabetic patients with available rest and stress gated myocardial perfusion single-photon emission computed tomographic data were enrolled. Stepwise Cox regression analysis was used to estimate cardiac death or nonfatal MI. Risk reclassification was calculated, and an exploratory analysis was performed to evaluate the effect of coronary revascularization on event-free survival. Adding TID to a multivariable model, including age, history of MI, stress type, poststress left ventricular ejection fraction, and stress-induced myocardial ischemia, improved discrimination of cardiac death or nonfatal MI (C statistic, 0.74–0.82; P =0.01; adjusted hazard ratio, 3.6; P <0.0001) and led to a net reclassification improvement of 0.39 (95% confidence interval, 0.14–0.64). Revascularization had a significant effect on event-free survival (adjusted hazard ratio, 0.25; P <0.001), with significant interactions between revascularization and poststress left ventricular ejection fraction, revascularization and stress-induced myocardial ischemia, and revascularization and TID (all P <0.01)

Conclusions—

TID provides independent and incremental prognostic information for the prediction of cardiac death or nonfatal MI in patients with diabetes mellitus. The addition of TID to a prediction model based on cardiovascular risk factors, left ventricular ejection fraction, and ischemia significantly improves risk discrimination and reclassification for incident cardiac events. The effect of revascularization seems to be influenced by left ventricular systolic function, stress-induced myocardial ischemia, and TID.

The prognostic value of transient ischemic dilatation with otherwise normal SPECT myocardial perfusion imaging: a cautionary note in patients with diabetes and coronary artery disease

BACKGROUND

The prognostic implications of transient ischemic dilatation (TID) of the left ventricle with otherwise normal single-photon emission computed tomography myocardial perfusion imaging (MPI) remain controversial. Whether this finding may have prognostic implications only in high-risk populations, such as patients with diabetes or manifest coronary artery disease (CAD), is uncertain.

METHODS

We conducted a prospective cohort study of 1,236 consecutive patients with normal (99m)Tc-sestamibi MPI, defined as normal perfusion (summed stress score = 0) and normal left ventricle volume and function. TID was defined as >2 standard deviations above the mean of patients with low likelihood of CAD.

RESULTS

The study subjects were followed for 27 ± 9 months. The 76 (6%) patients with TID had a greater rate of cardiac death or myocardial infarction (MI) [4 (5.3%) vs 11 (0.6%), P = .003] independent of covariates [hazard ratio = 6.4, P = .004]. This finding was entirely derived from the subgroup of 294 patients with diabetes or CAD [4 (13.3%) with TID vs 1 (0.4%) without TID, P = .001] independent of covariates. However, TID was not predictive of cardiac death or MI among the 941 patients without diabetes or CAD. Furthermore, TID was not predictive of coronary revascularization.

CONCLUSIONS

This study confirms a benign prognosis of TID with otherwise normal MPI in patients without diabetes or CAD, but cautions against extending this conclusion to high-risk individuals, particularly those with diabetes or CAD.

Impact of appropriate use on the prognostic value of single-photon emission computed tomography myocardial perfusion imaging

BACKGROUND

Appropriate use criteria (AUC) have been developed to aid in the optimal use of single-photon emission computed tomography (SPECT)-myocardial perfusion imaging (MPI), a technique that is a mainstay of risk assessment for ischemic heart disease. The impact of appropriate use on the prognostic value of SPECT-MPI is unknown.

METHODS AND RESULTS

A prospective cohort study of 1511 consecutive patients undergoing outpatient, community-based SPECT-MPI was conducted. Subjects were stratified on the basis of the 2009 AUC for SPECT-MPI into an appropriate or uncertain appropriateness group and an inappropriate group. Patients were prospectively followed up for 27±10 months for major adverse cardiac events of death, death or myocardial infarction, and cardiac death or myocardial infarction. In the entire cohort, the 167 subjects (11%) with an abnormal scan experienced significantly higher rates of major adverse cardiac events and coronary revascularization than those with normal MPI. Among the 823 subjects (54.5%) whose MPIs were classified as appropriate (779, 51.6%) or uncertain (44, 2.9%), an abnormal scan predicted a multifold increase in the rates of death (9.2% versus 2.6%; hazard ratio, 3.1; P=0.004), death or myocardial infarction (11.8% versus 3.3%; hazard ratio, 3.3; P=0.001), cardiac death or myocardial infarction (6.7% versus 1.7%; hazard ratio, 3.7; P=0.006), and revascularization (24.7% versus 2.7%; hazard ratio, 11.4; P<0.001). Among the 688 subjects (45.5%) with MPI classified as inappropriate, an abnormal MPI failed to predict major adverse cardiac events, although it was associated with a high revascularization rate. Furthermore, appropriate MPI use provided incremental prognostic value beyond myocardial perfusion and ejection fraction data.

CONCLUSIONS

When performed for appropriate indications, SPECT-MPI continues to demonstrate high prognostic value. However, inappropriate use lacks effectiveness for risk stratification, further emphasizing the need for optimal patient selection for cardiac testing.

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.

Assessment of transient ischemic dilation (TID) ratio in gated SPECT myocardial perfusion imaging (MPI) using regadenoson, a new agent for pharmacologic stress testing

BACKGROUND

Abnormal values of the transient ischemic dilation (TID) ratio are associated with severe and extensive coronary artery disease (CAD). The objective of this study was to determine the relationship between TID, determined from stress and rest ventricular volumes during regadenoson gated single-photon emission computed tomography myocardial perfusion imaging (MPI) dual isotope studies, and the extent of CAD found during coronary angiography.

METHODS

195 patients who underwent dual isotope MPI with regadenoson and cardiac angiography between March 2009 and February 2010 were analyzed. TID was calculated using commercially available software, Emory Cardiac Toolbox. Mean TID values were compared across disease types. A threshold for abnormal TID was determined by adding two standard deviations (SDs) to the mean TID of the "non-obstructive CAD" subgroup.

RESULTS

In the 195-patient group analyzed, the mean TID ratio for non-obstructive CAD (n = 104) was found to be 1.09 with a SD of 0.15. In a subgroup of patients whose angiogram was within 3 months of MPI (n = 155), the mean TIDs for non-obstructive disease (n = 81), single-vessel disease (n = 35), and multi-vessel disease (n = 39) were 1.09, 1.15, and 1.19 with SDs of 0.16, 0.19, and 0.26, respectively. Those with an abnormal TID had a crude and adjusted odds ratio of 3.4 for multi-vessel disease which was statistically significant. History of diabetes was not found to be a significant confounder, effect modifier, or mediator of the relationship between the TID and the vessel disease.

CONCLUSION

The mean TID ratio in patients with multi-vessel disease was 1.19. The threshold for an abnormal TID was 1.39 with specificity of 95% and sensitivity of 15% for determining multi-vessel CAD status. We conclude that the level of TID in gated SPECT MPI using regadenoson is associated with the degree of CAD on angiography.

Preload dependence of gated cardiac SPECT-derived ventricular volumes in hemodialysis patients

BACKGROUND

In hemodialysis (HD) patients, the intravascular volume expansion of the pre-HD state leads to a high preload. We aim to examine its effect on myocardial perfusion gated SPECT (MPGS)-derived left ventricular (LV) volumes.

METHODS

The study comprised 50 end-stage renal disease (ESRD) patients on HD with normal 2-day stress/rest MPGS performed for kidney transplantation risk assessment. Patients (pts) comprised 23 men/27 women, with mean age of 59.4 ± 7.1 years. The time elapsed from the last HD session in hours was calculated on both days, and patients were classified according to whether it was higher (group A: 19 pts), lower (group B: 27 pts), or equal (group C: 4 pts) on the stress vs the rest day. End-diastolic, end-systolic volumes (EDV, ESV), and left ventricular ejection fraction (LVEF) were determined using QGS™ software. Transient ischemic dilation (TID) ratios were derived from the nongated images using QPS™ software.

RESULTS

Volumes were significantly higher at stress in group A, at rest in group B, and similar in group C. TID ratios were significantly higher in group A vs groups B and C.

CONCLUSIONS

MPGS-derived ventricular volumes are preload dependent. The high preload of the pre-HD state may mimic ischemic TID if occurring on the stress day and create confusion if coinciding with the rest day.

Transient ischemic dilation for coronary artery disease in quantitative analysis of same-day sestamibi myocardial perfusion SPECT

BACKGROUND

Transient ischemic dilation (TID) of the left ventricle in myocardial perfusion SPECT (MPS) has been shown to be a clinically useful marker of severe coronary artery disease (CAD). However, TID has not been evaluated for 99mTc-sestamibi rest/stress protocols (Mibi-Mibi). We aimed to develop normal limits and evaluate diagnostic power of TID ratio for Mibi-Mibi scans.

METHODS

TID ratios were automatically derived from static rest/stress MPS (TID) and gated rest/stress MPS from the end-diastolic phase (TID(ed)) in 547 patients who underwent Mibi-Mibi scans [215 patients with correlating coronary angiography and 332 patients with low likelihood (LLk) of CAD]. Scans were classified as severe (≥ 70% stenosis in proximal left anterior descending (pLAD) artery or left main (LM), or ≥ 90% in ≥ 2 vessels), mild to moderate (≥ 90% stenosis in 1 vessel or ≥ 70%-90% in ≥ 1 vessel except pLAD or LM), and normal (<70% stenosis or LLk group). Another classification based on the angiographic Duke prognostic CAD index (DI) was also applied: DI ≥ 50, 30 ≤ DI < 50 and DI < 30 or LLk group.

RESULTS

The upper normal limits were 1.19 for TID and 1.23 for TID(ed) as established in 259 LLk patients. Both ratios increased with disease severity (P < .0001). Incidence of abnormal TID increased from 2% in normal patients to >36% in patients with severe CAD. Similarly, when DI was used to classify disease severity, the average ratios showed significant increasing trend with DI increase (P < .003); incidence of abnormal TID also increased with increasing DI. The incidence of abnormal TID in the group with high perfusion scores significantly increased compared to the group with low perfusion scores (stress total perfusion deficit, TPD < 3%) (P < .0001). The sensitivity for detecting severe CAD improved for TID when added to mild to moderate perfusion abnormality (3% ≤ TPD < 10%): 71% vs 64%, P < .05; and trended to improve for TID(ed)/TID(es): 69% vs 64%, P = .08, while the accuracy remained consistent if abnormal TID was considered as a marker in addition to stress TPD. Similar results were obtained when DI was used for the definition of severe CAD (sensitivity: 76% vs 66%, P < .05 when TID was combined with stress TPD).

CONCLUSION

TID ratios obtained from gated or ungated Mibi-Mibi MPS and are useful markers of severe CAD.

Quantitative analysis of perfusion studies: strengths and pitfalls

Tools for automated quantification of myocardial perfusion are available to nuclear cardiology practitioners and researchers. These methods have demonstrated superior reproducibility with comparable diagnostic and prognostic performance, when compared with segmental visual scoring by expert observers. A particularly useful application of the quantitative analysis can be in the detection of subtle changes or in precise determination of ischemia. Some challenges remain in the routine application of perfusion quantification. Multiple quantitative parameters may need to be reconciled by the expert reader for the final diagnosis. Computer analysis may be sensitive to imaging artifacts, resulting in false positive scans. Perfusion quantification may require site specific normal limits and some degree of manual interaction. New software improvements have been proposed to address some of these challenges.

The prevalence and predictive accuracy of quantitatively defined transient ischemic dilation of the left ventricle on otherwise normal SPECT myocardial perfusion imaging studies

AIM

TID in the setting of otherwise normal MPI has been suggested as a marker of high risk CAD. In this study we estimate the variance of TID in a normal population and the statistical frequency of false positive TID. This will provide an indirect measurement of predictive accuracy (PA) in a mixed referral population.

OBJECTIVE

To study the PA of TID in otherwise normal MPI.

METHODS

688 consecutive patients were studied. We defined TID according to the standard method at 2 cut-off values; 1SD and 2SD, and also by a BSA normalized volume difference with gender-specific 2SD limits (NrVD).

RESULTS

457 patients with otherwise normal MPI were analyzed. PA of TID at 1SD was 4% and 26% at 2SD. PA was slightly higher (42%) using the NrVD, however, still too low to be clinically useful as a high-risk marker. PA of TID in patients with perfusion abnormalities was 58% at 1SD, 80% at 2SD and slightly higher (93%) by NrVD.

CONCLUSIONS

In the setting of otherwise normal MPI, elevated TIDr has a low prevalence and poor predictive accuracy and should not be considered summarily as a marker of high risk CAD.