Extent and severity of myocardial hypoperfusion as predictors of prognosis in patients with suspected coronary artery disease

Concordance between vessel-specific and vascular territory coronary functional assessment: A comparison of quantitative flow ratio and myocardial perfusion scintigraphy

BACKGROUND

Quantitative flow ratio (QFR) and myocardial perfusion scintigraphy (MPS) are utilized for assessing coronary artery disease (CAD) significance. We aimed to analyze their concordance and prognostic impact.

AIMS

We aimed to analyze the concordance between QFR and MPS and their risk stratification.

METHODS

Patients with invasive coronary angiography and MPS were categorized as concordant if QFR ≤ 0.80 and summed difference score (SDS) ≥ 4 or if QFR > 0.80 and SDS < 4; otherwise, they were discordant. Concordance was classified by coronary territory involvement: total (three territories), partial (two territories), poor (one territory), and total discordance (zero territories). Leaman score assessed coronary atherosclerotic burden.

RESULTS

2010 coronary territories (670 patients) underwent joint QFR and MPS analysis. MPS area under the curve for QFR ≤ 0.80 was 0.637. Concordance rates were total (52.5%), partial (29.1%), poor (15.8%), and total discordance (2.6%). Most concordance occurred in patients without significant CAD or with single-vessel disease (89.5%), particularly without MPS perfusion defects (91.5%). Leaman score (odds ratio [OR]: 0.839, 95% confidence interval [CI]: 0.805-0.875, p < 0.001) and MPS perfusion defect (summed stress score [SSS] ≥ 4) (OR: 0.355, 95% CI: 0.211-0.596, p < 0.001) were independent predictors for discordance. After 1400 days, no significant difference in death/myocardial infarction was observed based on MPS assessment, but Leaman score, functional Leaman score, and average QFR identified higher risk patients.

CONCLUSIONS

MPS showed good overall accuracy in assessing QFR significance but substantial discordance existed. Predictors for discordance included higher atherosclerotic burden and MPS perfusion defects (SSS ≥ 4). Leaman score, QFR-based functional Leaman score, and average QFR provided better risk stratification for all-cause death and myocardial infarction than MPS.

Comparative predictors of mortality among patients referred for stress single-photon emission computed tomography versus positron emission tomography myocardial perfusion imaging

BACKGROUND

There is currently little information regarding the usage and comparative predictors of mortality among patients referred for single-photon emission computed tomography (SPECT) versus positron emission tomography (PET) myocardial perfusion imaging (MPI) within multimodality imaging laboratories.

METHODS

We compared the clinical characteristics and mortality outcomes among 15,718 patients referred for SPECT-MPI and 6202 patients referred for PET-MPI between 2008 and 2017.

RESULTS

Approximately two-thirds of MPI studies were performed using SPECT-MPI. The PET-MPI group was substantially older and included more patients with known coronary artery disease (CAD), hypertension, diabetes, and myocardial ischemia. The annualized mortality rate was also higher in the PET-MPI group, and this difference persisted after propensity matching 3615 SPECT-MPI and 3615 PET-MPI patients to have similar clinical profiles. Among the SPECT-MPI patients, the most potent predictor of mortality was exercise ability and performance, including consideration of patients' mode of stress testing and exercise duration. Among the PET-MPI patients, myocardial flow reserve (MFR) was the most potent predictor of mortality.

CONCLUSIONS

In our real-world setting, PET-MPI was more commonly employed among older patients with more cardiac risk factors than SPECT-MPI patients. The most potent predictors of mortality in our SPECT and PET-MPI groups were variables exclusive to each test: exercise ability/capacity for SPECT-MPI patients and MFR for PET-MPI patients.

Assessment of lifestyle-related risk factors enhances the effectiveness of cardiac stress testing

Cardiac stress tests have been widely utilized since the 1960s for the diagnostic and prognostic assessment of patients with suspected coronary artery disease (CAD). Clinical risk is primarily based on assessing the presence and magnitude of inducible myocardial ischemia. However, the primary factors driving mortality risk have changed over recent decades. Factors such as typical angina and inducible ischemia have decreased, whereas the percentage of patients with diabetes, obesity and hypertension have increased. There has also been a marked temporal increase in the percentage of patients who require pharmacologic testing due to inability to perform treadmill exercise at the time of cardiac stress testing and this need has emerged as the most potent predictor of mortality risk in contemporary stress test populations. However, the long-term clinical risk posed by the inability to perform exercise and concomitant CAD risk factors are rarely reflected in the assessment of patients' prognostic risk in cardiac stress test reports. In this review, we suggest that the clinical utility of present-day cardiac stress testing can be improved by developing a more comprehensive assessment that integrates and reports all factors which modulate patients' long-term clinical risk following stress testing. This should include assessment of patients' CAD risk factors, physical activity habits and mobility risks, identification of the reasons why patients could not exercise at the time of cardiac stress testing. In addition, the assessment of four core non-aerobic functional parameters should be considered among patients who cannot exercise: assessment of gait speed, handgrip strength, lower extremity strength, and standing balance.

Benefit of Early Revascularization Based on Inducible Ischemia and Left Ventricular Ejection Fraction

BACKGROUND

The utility of performing early myocardial revascularization among patients presenting with inducible myocardial ischemia and low left ventricular ejection fraction (LVEF) is currently unknown.

OBJECTIVES

In this study, we sought to assess the relationship between stress-induced myocardial ischemia, revascularization, and all-cause mortality (ACM) among patients with normal vs low LVEF.

METHODS

We evaluated 43,443 patients undergoing stress-rest single-photon emission computed tomography myocardial perfusion imaging from 1998 to 2017. Median follow-up was 11.4 years. Myocardial ischemia was assessed for its interaction between early revascularization and mortality. A propensity score was used to adjust for nonrandomization to revascularization, followed by multivariable Cox modeling adjusted for the propensity score and clinical variables to predict ACM.

RESULTS

The frequency of myocardial ischemia varied markedly according to LVEF and angina, ranging from 6.7% among patients with LVEF ≥55% and no typical angina to 64.0% among patients with LVEF <45% and typical angina (P < 0.001). Among 39,883 patients with LVEF ≥45%, early revascularization was associated with increased mortality risk among patients without ischemia and lower mortality risk among patients with severe (≥15%) ischemia (HR: 0.70; 95% CI: 0.52-0.95). Among 3,560 patients with LVEF <45%, revascularization was not associated with mortality benefit among patients with no or mild ischemia, and was associated with decreased mortality among patients with moderate (10%-14%) (HR: 0.67; 95% CI: 0.49-0.91) and severe (≥15%) (HR: 0.55; 95% CI: 0.38-0.80) ischemia.

CONCLUSIONS

Within this cohort, early myocardial revascularization was associated with a significant reduction in mortality among both patients with normal LVEF and severe inducible myocardial ischemia and patients with low LVEF and moderate or severe inducible myocardial ischemia.

Non-traditional factors affecting referral for coronary angiography following SPECT myocardial perfusion imaging

BACKGROUND

The use of myocardial perfusion imaging (MPI) in the management of coronary artery disease (CAD) is well established. Although prior studies have shown disparities in the use of invasive angiography in patients with acute MI, data on factors affecting referral to angiography post-MPI are lacking. We sought to evaluate the primary determinants of referral to invasive angiography post-MPI and specifically assess the role of non-traditional non-clinical factors such as race/ethnicity, socioeconomic factors, insurance status, and marital status.

METHODS

All patients without known CAD who underwent stress SPECT MPI over 15 years were reviewed and the performance of coronary angiography within 90 days of their MPI was recorded. Multiple factors were analyzed for an association with referral to angiography, including exercise and MPI results, baseline demographics, traditional cardiac risk factors, and non-traditional factors such as ethnicity, insurance, marital and socioeconomic status. In a secondary analysis, these factors were assessed with regard to abnormal MPI results.

RESULTS

Out of 27,895 total patients, 2,150 (7.7%) underwent invasive coronary angiography. On multivariate analysis, inpatient location, positive ECG response, and abnormal MPI results were the strongest predictors of angiography. Non-traditional factors such as race/ethnicity and insurance status had a significant association with referral to angiography with Caucasians (OR 1.42, 95% CI 1.18-1.71, P < .0001) and those with private insurance (OR 1.35, 95% CI 1.13-1.62, P = .001) or Medicare (OR 1.30, 95% CI 1.08-1.56, P = .006) having higher rates of angiography despite controlling for traditional risk factors and test results.

CONCLUSION

Our study results indicate that non-traditional factors such as race/ethnicity and insurance status influence patient management decisions and impact the performance of downstream cardiac invasive testing after stress MPI. Higher rates of angiography in Caucasians, privately insured and Medicare patients were seen despite controlling for traditional risk factors and abnormal test results. Further research is needed to better understand these disparities, especially in the current healthcare environment.

Predictive value of SPECT myocardial perfusion imaging in patients with unrevascularized coronary chronic total occlusion

OBJECTIVE

Data involved the association between myocardial ischaemia and the outcome for unrevascularized coronary chronic total occlusion (CTO) patients were limited. The purpose of this study was to evaluate the predictive value of ischaemia detected by single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the adverse events in unrevascularized CTO patients. We further explored whether ischaemia generated from CTO vessel can independently predict the outcome.

METHODS

Patients with at least one unrevascularized CTO on coronary angiography were enrolled in this study. Exercise stress/rest SPECT MPI was performed in all patients. All patients were then followed by telephone interview and reviewing of medical records.

RESULTS

Patients with ischaemia experienced significantly higher rate of adverse events than non-ischaemia patients (40.7% vs 7.1%, P = 0.002). Ischaemia demonstrated on MPI [odds ratio (OR) = 7.656; 95% confidence interval (CI) 1.598-36.677; P = 0.011] was an independent predictor for adverse events. Moreover, CTO-ischaemia (OR = 5.466; 95% CI 1.015-29.420; P = 0.048), non-CTO ischaemia (OR = 29.174; 95% CI 3.245-262.322; P = 0.003), mixed-ischaemia (OR = 7.130, 95% CI 1.257-40.445; P = 0.027) were all independent predictors for outcome.

CONCLUSION

Ischaemia demonstrated on MPI, especially CTO-ischaemia were independent predictors for the adverse events. SPECT MPI can aid to identify patients at risk of adverse events, who may benefit from subsequent CTO percutaneous coronary intervention.

Association Between Change in Circulating Progenitor Cells During Exercise Stress and Risk of Adverse Cardiovascular Events in Patients With Coronary Artery Disease

Importance

Stem and progenitor cells mobilize from the bone marrow in response to myocardial ischemia. However, the association between the change in circulating progenitor cell (CPC) counts and disease prognosis among patients with ischemia is unknown.

Objective

To investigate the association between the change in CPC counts during stress testing and the risk of adverse cardiovascular events in patients with stable coronary artery disease (CAD).

Design, Setting, and Participants

This prospective cohort study included a population-based sample of 454 patients with stable CAD who were recruited between June 1, 2011, and August 15, 2014, at Emory University-affiliated hospitals and followed up for 3 years. Data were analyzed from September 15, 2018, to October 15, 2018.

Exposures

Myocardial perfusion imaging with technetium Tc 99m sestamibi at rest and 30 to 60 minutes after conventional stress testing.

Main Outcomes and Measures

Circulating progenitor cells were enumerated with flow cytometry as CD34-expressing mononuclear cells (CD45med/CD34+), with additional quantification of subsets coexpressing the chemokine (C-X-C motif) receptor 4 (CD34+/CXCR4+). Changes in CPC counts were calculated as poststress minus resting CPC counts. Cox proportional hazards regression models were used to identify factors associated with the combined end point of cardiovascular death and myocardial infarction after adjusting for clinical covariates, including age, sex, race, smoking history, body mass index, and history of heart failure, hypertension, dyslipidemia, and diabetes.

Results

Of the 454 patients (mean [SD] age, 63 [9] years; 76% men) with stable CAD enrolled in the study, 142 (31.3%) had stress-induced ischemia and 312 (68.7%) did not, as measured by single-photon emission computed tomography. During stress testing, patients with stress-induced ischemia had a mean decrease of 20.2% (interquartile range [IQR], -45.3 to 5.5; P < .001) in their CD34+/CXCR4+ counts, and patients without stress-induced ischemia had a mean increase of 3.2% (IQR, -20.6 to 35.1; P < .001) in their CD34+/CXCR4+ counts. Twenty-four patients (5.2%) experienced adverse events. After adjustment, baseline CPC counts were associated with worse adverse outcomes, but this association was not present after stress-induced ischemia was included in the model. However, the change in CPC counts during exercise remained significantly associated with adverse events (hazard ratio, 2.59; 95% CI, 1.15-5.32, per 50% CD34+/CXCR4+ count decrease), even after adjustment for clinical variables and the presence of ischemia. The discrimination of risk factors associated with incident adverse events improved (increase in C statistic from 0.72 to 0.77; P = .003) with the addition of the change in CD34+/CXCR4+ counts to a model that included clinical characteristics, baseline CPC count, and ischemia.

Conclusions and Relevance

In this study of patients with CAD, a decrease in CPC counts during exercise is associated with a worse disease prognosis compared with the presence of stress-induced myocardial ischemia. Further studies are needed to evaluate whether strategies to improve CPC responses during exercise stress will be associated with improvements in the prognosis of patients with CAD.

Myocardial perfusion scintigraphy for risk stratification of patients with coronary artery disease: the AMICO registry

AIMS

We assessed the prognostic value of myocardial perfusion scintigraphy (MPS) with cadmium-zinc-telluride in addition to clinical and coronary anatomy analysis.

METHODS AND RESULTS

We prospectively enrolled 1464 patients (26% females, 69.5 ± 10.4 years) referred for stress-rest MPS. All the patients underwent invasive coronary angiography (1171, 80%) or coronary computed tomography angiography (293, 20%). We defined a composite endpoint of cardiovascular death and non-fatal MI. After an 8-year follow-up, summed stress score (SSS) had the highest accuracy in predicting primary endpoint with a ROC-derived cut-off of SSS >8 (>10% myocardium). SSS >8 portended the lowest survival probability at Kaplan-Meier analysis (P < 0.0001 for the composite endpoint and individual components). The Cox-regression analysis indicated SSS as an independent predictor of the composite endpoint, along with fasting blood glucose and total cholesterol and contrary to coronary anatomy parameters. Patients with SSS >8 treated with optimal medical therapy (OMT) had the largest area of necrosis, the lower ischaemic burden, the most compromised LV systo-diastolic function and the highest LV mass, but received a less aggressive treatment in comparison to early revascularized patients. Survival analysis revealed patients with SSS ≤8 had the greater freedom from events, irrespective of the treatment strategy, while the group with SSS >8 and OMT had the worst outcome, followed by patients with SSS >8 and early revascularization (log-rank test: all P < 0.0001).

CONCLUSION

MPS-SSS constitutes a strong independent predictor of future adverse events after adjustment for multiple clinical parameters and coronary angiography. In particular, MPS could help risk stratification of patients who did not undergo early revascularization.

Head-to-Head Comparison of the Incremental Predictive Value of The Three Established Risk Markers, Hs-troponin I, C-Reactive Protein, and NT-proBNP, in Coronary Artery Disease

Risk stratification among patients with coronary artery disease (CAD) is of considerable interest to potentially guide secondary preventive therapies. Cardiac troponins as well as C-reactive protein (hsCRP) and natriuretic peptides have emerged as biomarkers for risk stratification. The question remains if one of these biomarkers is superior in predicting adverse outcomes. Thus, we perform a head-to-head comparison between high-sensitivity troponin I (hsTnI), hsCRP, and N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with CAD. Plasma levels were measured in a cohort of 2193 patients with documented CAD. The main outcome measures were cardiovascular (CV) death and/or nonfatal myocardial infarction (MI). During a median follow-up of 3.8 years, all three biomarkers were associated with cardiovascular death and/or MI. After adjustments for conventional cardiovascular risk factors, the hazard ratio (HR) per standard deviation (SD) for the prediction of CV death and/or nonfatal MI was 1.39 [95% CI: 1.24–1.57, p < 0.001] for hsTnI, 1.41 [95% CI: 1.24–1.60, p < 0.001] for hsCRP, and 1.64 [95% CI: 1.39–1.92, p < 0.001] for NT-proBNP. However, upon further adjustments for the other two biomarkers, only NT-proBNP was still associated with the combined endpoint with an HR of 1.47 [95% CI: 1.19–1.82, p < 0.001]. Conclusively, NT-proBNP is reliably linked to CV death and MI in patients with CAD and provides incremental value beyond hsCRP and hsTnI.

[Comparison of the prognostic value of different clinical, angiographic and scintigraphic scores in stable coronary patients after acute coronary syndrome]

INTRODUCTION

To date, there is no consensus regarding the follow-up of asymptomatic coronary patients with an intermediate risk of events. Indeed, most of cardiovascular events (CVE) occur in asymptomatic patients, hence the clinician's interest in establishing risk stratification scores. In asymptomatic patient, the risk assessment after acute coronary syndrome (ACS) can currently be based on 3 types of score: clinical with, for example, the REACH score; angiographic with the residual SYNTAX score; imaging with different scintigraphic scores. These scores differ widely in terms of evaluation criteria and period of analysis. The aim of our study was therefore, in stable and asymptomatic coronary patients after ACS, to compare these different predictive scores; to establish that the combination of these scores makes it possible to optimize the risk assessment during the follow-up.

METHODS

Our retrospective study included 236 revascularized patients after ACS. Three different risk scores were collected: 1) the residual SYNTAX score, calculated at the time of revascularization; 2) the scintigraphic risk score described by Sharir et al., performed 3 to 12 months after the event and taking into account the extent of ischemia (SDS) and the poststress left ventricular ejection fraction (LVEF). Patients with LVEF <50% and/or moderate to severe ischemic disease (SDS≥2) were considered with an intermediate or high scintigraphic risk; 3) the REACH clinical score calculated on the day of the scintigraphic examination. After the myocardial scintigraphic exam, patients had a 1-year follow-up and CVE were recorded. Continuous data were analyzed either by Student's t-test or non-parametric Mann-Whitney test. The dichotomous data were compared either by the χ² test or by Fisher's exact test.

RESULTS

Forty-eight patients (20.1%) had a CVE during the 1-year follow-up. Thirty patients (13.8%) had a high residual SYNTAX score (≥8) without any correlation observed between the residual SYNTAX score and CVE (P=0.359). 148 patients (57.7%) had a high REACH clinical score (≥11) with no significant correlation observed with CVE (P=0.079). Lastly, 34 patients (14.4%) had an intermediate or high scintigraphic score, this imaging score being strongly correlated with a greater number of CVE (P<0.001). Multivariate analysis revealed 3 independent factors associated with CVE: a scintigraphic score> 2 (OR [(95% CI): 5.530 [2.426-12.605] P<0.001); Peripheral Arterial Obstructive Disease (PAOD) (OR [95% CI]: 8.531 [2.540-28.660] P<0.001); diabetes (OR [95% CI]: 2.86 [1.262-6.517] P=0,012).

CONCLUSION

The combination of the scintigraphic score with two clinical factors, such as PAOD and diabetes, provides optimal prognostic value in the evaluation of asymptomatic and stable patients after ACS. Our study therefore highlights the importance of optimizing evaluation strategies in the follow-up of these patients who remain at risk of post-revascularization CVE.

Algorithmic Versus Expert Human Interpretation of Instantaneous Wave-Free Ratio Coronary Pressure-Wire Pull Back Data

OBJECTIVES

The aim of this study was to investigate whether algorithmic interpretation (AI) of instantaneous wave-free ratio (iFR) pressure-wire pull back data would be noninferior to expert human interpretation.

BACKGROUND

Interpretation of iFR pressure-wire pull back data can be complex and is subjective.

METHODS

Fifteen human experts interpreted 1,008 iFR pull back traces (691 unique, 317 duplicate). For each trace, experts determined the hemodynamic appropriateness for percutaneous coronary intervention (PCI) and, in such cases, the optimal physiological strategy for PCI. The heart team (HT) interpretation was determined by consensus of the individual expert opinions. The same 1,008 pull back traces were also interpreted algorithmically. The coprimary hypotheses of this study were that AI would be noninferior to the interpretation of the median expert human in determining: 1) the hemodynamic appropriateness for PCI; and 2) the physiological strategy for PCI.

RESULTS

Regarding the hemodynamic appropriateness for PCI, the median expert human demonstrated 89.3% agreement with the HT in comparison with 89.4% for AI (p < 0.01 for noninferiority). Across the 372 cases judged as hemodynamically appropriate for PCI according to the HT, the median expert human demonstrated 88.8% agreement with the HT in comparison with 89.7% for AI (p < 0.0001 for noninferiority). On reproducibility testing, the HT opinion itself changed 1 in 10 times for both the appropriateness for PCI and the physiological PCI strategy. In contrast, AI showed no change.

CONCLUSIONS

AI of iFR pressure-wire pull back data was noninferior to expert human interpretation in determining both the hemodynamic appropriateness for PCI and the optimal physiological strategy for PCI.

Coronary-to-pulmonary artery fistula in adults: Evaluation with thallium-201 myocardial perfusion SPECT

Objectives

With the increasing use of multi-detector CT, the number of detected cases with coronary-to-pulmonary artery fistula (CPAF) has increased. Several previous studies reported severe cases of angina, but no appropriate tests to evaluate myocardial perfusion for patients with CPAF have been established. We evaluated the hemodynamic characteristics of CPAF using thallium-201 (Tl-201) single photon emission computed tomography (SPECT).

Materials and methods

Tl-201 SPECT was performed in 17 patients with CPAF, but without evidence of coronary artery disease on coronary computed tomography angiography (CCTA) (age, 58.5±13.3 years; 8 men). Quantitative analysis of scintigraphic data was performed. Additionally, perfusion abnormalities were compared with CCTA findings. Medical records were obtained to define clinical data, diagnostic findings, symptoms, management, follow-up data, and major adverse cardiac events (MACE).

Results

Six patients (35.2%) showed perfusion abnormalities on SPECT studies and could be classified as follows: 3 patients, no reversible ischemia (3/17, 17.6%); 1 patient, mild ischemia (1/17, 5.8%); and 2 patients, moderate ischemia (2/17, 11.7%). During the follow-up, ten patients (58.8%) improved under medical management and 5 patients (29.4%) underwent surgical ligation for CPAF with symptomatic improvement in 4 patients. Seven patients performed follow-up myocardial perfusion SPECT, and symptomatic improvement correlated well with scintigraphic perfusion improvement in 6 patients No MACE was observed.

Clinical significance

Tl-201 myocardial perfusion SPECT might be useful for determining the hemodynamic status and for risk stratification in patients with CPAF.

The elusive role of myocardial perfusion imaging in stable ischemic heart disease: Is ISCHEMIA the answer?

The assessment of ischemia through myocardial perfusion imaging (MPI) is widely accepted as an index step in the diagnostic evaluation of stable ischemic heart disease (SIHD). Numerous observational studies have characterized the prognostic significance of ischemia extent and severity. However, the role of ischemia in directing downstream SIHD care including coronary revascularization has remained elusive as reductions in ischemic burden have not translated to improved clinical outcomes in randomized trials. Importantly, selection bias leading to the inclusion of many low risk patients with minimal ischemia have narrowed the generalizability of prior studies along with other limitations. Accordingly, an ongoing randomized controlled trial entitled ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) will compare an invasive coronary revascularization strategy vs a conservative medical therapy approach among stable patients with moderate to severe ischemia. The results of ISCHEMIA may have a substantial impact on the management of SIHD and better define the role of MPI in current SIHD pathways of care.

Prognostic Impact of Extent, Severity, and Heterogeneity of Abnormalities on 18F-FDG PET Scans for Suspected Cardiac Sarcoidosis

OBJECTIVES

This study sought to evaluate the incremental value of quantifying the extent and severity of myocardial perfusion and ¹⁸F-labeled fluorodeoxyglucose (FDG) abnormalities in predicting adverse outcomes among patients with suspicion for cardiac sarcoidosis (CS).

BACKGROUND

Positron emission tomography (PET) with FDG is a key component of the noninvasive assessment of patients with suspected CS. However, the optimal method for image interpretation has not been defined.

METHODS

A retrospective analysis was performed of 203 patients who underwent perfusion and FDG-PET imaging to evaluate for CS. Imaging findings were scored by conventional 3-category methods (normal perfusion and metabolism, abnormal perfusion or metabolism, abnormal perfusion and metabolism) and by summed scores using the 17-segment model to represent extent and severity of disease. Heterogeneity of metabolism was quantified using the coefficient of variation (SD divided by the mean) of FDG uptake. Multivariable Cox models were developed to assess associations between imaging findings and adverse events (death, heart transplant, or ventricular arrhythmia requiring defibrillation).

RESULTS

The indication for FDG-PET was ventricular arrhythmia in 69 (34%), heart block in 16 (8%), cardiomyopathy in 54 (27%), and other indications in 64 (32%). There were 63 patients who developed adverse events over a mean follow-up of 1.8 years. After robust adjustment, only the summed score in segments with a perfusion-metabolism mismatch and the coefficient of variation were important prognostically (p = 0.029 and p = 0.041, respectively).

CONCLUSIONS

Quantitative measures of extent and severity of perfusion-metabolism mismatch and coefficient of variation of FDG uptake provide an incremental prognostic advantage in patients undergoing FDG-PET for CS. These results support the use of a more detailed analysis of imaging findings, as is conventional in coronary artery disease.

Visualization of the improvement of myocardial perfusion after coronary intervention using motorized fractional flow reserve pullback curve

This study aimed to evaluate the feasibility and utility of using motorized pullback of the pressure guidewire to provide a graphic assessment and prediction of the benefits of coronary intervention. Fractional flow reserve (FFR) measurements were performed with motorized pullback imaging in 20 patients who underwent successful percutaneous coronary intervention (PCI) of the left anterior descending artery. Physiological lesion length (PLL) was calculated using frame counts to determine stent length. FFR area was calculated by integrating the FFR values recorded during pullback tracing (FFRarea). The percentage increase in FFR area (%FFRarea) was defined as the ratio of the difference between the pre- and post-intervention FFRarea to the total frame count. The average FFR values were enhanced following PCI, from 0.64 to 0.82, and the median value of the difference between pre- and post-interventional FFR values (D-FFR) and %FFRarea were 0.13 and 10.6%, respectively. The %FFRarea demonstrated a significant positive correlation with D-FFR (R², 0.61; p < 0.01). PLL tended to be longer and the %FFRarea was smaller in lesions with a gradual pressure-drop pattern than those with an abrupt pressure-drop pattern (35.37 vs. 20.40 mm, p = 0.07; 5.78 vs. 16.21%, p < 0.05, respectively). Motorized pullback tracing was able to identify the extent and location of stenosis and help in appropriate stent implantation, in addition to visualizing and quantifying the improvement in FFR following PCI.

Evaluation of computed tomography in patients with atypical angina or chest pain clinically referred for invasive coronary angiography: randomised controlled trial

OBJECTIVE

 To evaluate whether invasive coronary angiography or computed tomography (CT) should be performed in patients clinically referred for coronary angiography with an intermediate probability of coronary artery disease.

DESIGN

 Prospective randomised single centre trial.

SETTING

 University hospital in Germany.

PARTICIPANTS

 340 patients with suspected coronary artery disease and a clinical indication for coronary angiography on the basis of atypical angina or chest pain.

INTERVENTIONS

 168 patients were randomised to CT and 172 to coronary angiography. After randomisation one patient declined CT and 10 patients declined coronary angiography, leaving 167 patients (88 women) and 162 patients (78 women) for analysis. Allocation could not be blinded, but blinded independent investigators assessed outcomes.

MAIN OUTCOME MEASURE

 The primary outcome measure was major procedural complications within 48 hours of the last procedure related to CT or angiography.

RESULTS

 Cardiac CT reduced the need for coronary angiography from 100% to 14% (95% confidence interval 9% to 20%, P<0.001) and was associated with a significantly greater diagnostic yield from coronary angiography: 75% (53% to 90%) v 15% (10% to 22%), P<0.001. Major procedural complications were uncommon (0.3%) and similar across groups. Minor procedural complications were less common in the CT group than in the coronary angiography group: 3.6% (1% to 8%) v 10.5% (6% to 16%), P=0.014. CT shortened the median length of stay in the angiography group from 52.9 hours (interquartile range 49.5-76.4 hours) to 30.0 hours (3.5-77.3 hours, P<0.001). Overall median exposure to radiation was similar between the CT and angiography groups: 5.0 mSv (interquartile range 4.2-8.7 mSv) v 6.4 mSv (3.4-10.7 mSv), P=0.45. After a median follow-up of 3.3 years, major adverse cardiovascular events had occurred in seven of 167 patients in the CT group (4.2%) and six of 162 (3.7%) in the coronary angiography group (adjusted hazard ratio 0.90, 95% confidence interval 0.30 to 2.69, P=0.86). 79% of patients stated that they would prefer CT for subsequent testing. The study was conducted at a University hospital in Germany and thus the performance of CT may be different in routine clinical practice. The prevalence was lower than expected, resulting in an underpowered study for the predefined primary outcome.

CONCLUSIONS

 CT increased the diagnostic yield and was a safe gatekeeper for coronary angiography with no increase in long term events. The length of stay was shortened by 22.9 hours with CT, and patients preferred non-invasive testing.Trial registration ClinicalTrials.gov NCT00844220.

Prognostic impact of location and extent of vessel-related ischemia at myocardial perfusion scintigraphy in patients with or at risk for coronary artery disease

BACKGROUND

Myocardial perfusion scintigraphy (MPS) has an established diagnostic and prognostic role in patients with or at risk for coronary artery disease, with ischemia severity and extent having already been identified as key predictors. Whether this is affected by the location of myocardial ischemia is uncertain. We aimed at comparing the prognostic outlook of patients undergoing MPS according to the site of ischemia.

METHODS

Our institutional database was queried for subjects undergoing MPS, without myocardial necrosis or recent revascularization. We focused on the prognostic impact of location of vessel-related ischemia (VRI) at MPS, distinguishing four mutually exclusive groups: single-VRI involving left anterior descending (LAD), single-VRI not involving LAD, multi-VRI involving LAD, and multi-VRI not involving LAD. The primary outcome was the long-term (>1 year) rate of death or myocardial infarction (D/MI).

RESULTS

A total of 13,254 patients were included. Moderate or severe VRI occurred in 2,627 (20%) patients. Clinical outcomes were significantly different among the groups of patients with moderate or severe VRI, including death, cardiac death, non-fatal myocardial infarction or their composites (overall P < .001). Specifically, and excluding subjects undergoing revascularization as first follow-up event, D/MI occurred in 8.4% of patients with single-VRI involving LAD, 5.5% of subjects with single-VRI not involving LAD, 16.5% of those with multi-VRI involving LAD, and 7.3% of patients with multi-VRI not involving LAD (overall P < .001). Even at incremental multivariable Cox proportional analysis, hierarchical VRI was independently associated with an increased risk of D/MI [hazard ratio = 1.17 (1.04-1.08) for each class increment, P = .010].

CONCLUSIONS

Location and extent of myocardial ischemia at MPS according to the VRI concept have a hierarchical predictive impact, with multi-VRI involving LAD being significantly and independently more prognostically ominous than other types of VRI.

Long-Term Risk Assessment After the Performance of Stress Myocardial Perfusion Imaging

Stress-rest myocardial perfusion imaging (MPI) is a potent method for assessing the presence and magnitude of inducible myocardial ischemia. Stress MPI currently faces increased scrutiny for its therapeutic effectiveness because of the emergence of other competing means for assessing clinical risk. New data have examined the usefulness stress-rest-MPI as a predictor for long-term clinical outcomes, in contrast to its traditional role for assessing short-term cardiovascular risk. These data indicates that temporal risk is highly influenced by both the magnitude of ischemia and various baseline clinical factors. An optimized assessment of stress MPI, which includes long-term risk prediction, might improve the potential future clinical effectiveness of this imaging modality.

Comparison of the prognostic value of regadenoson and adenosine myocardial perfusion imaging

BACKGROUND

Regadenoson is now widely used in single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). However, the prognostic value of abnormal stress perfusion findings with regadenoson vs adenosine are unclear. The aim of this study was to evaluate the prognostic value of regadenoson SPECT and to compare it to that of adenosine SPECT.

METHODS AND RESULTS

3698 consecutive patients undergoing either adenosine or regadenoson SPECT were assessed at 1 year for the endpoints of cardiovascular death and a composite endpoint of cardiovascular death or MI. Weighted Cox proportional hazards regression modeling with the inverse probability weighted (IPW) estimators method adjusting to propensity for agent was used to account for differences in baseline characteristics. Patients undergoing adenosine SPECT MPI had a significantly higher prevalence of smoking history, diabetes, hypertension, and prior myocardial infarction (P < .05, all). At 1 year of follow-up, there were 154 cardiovascular deaths and 204 with the composite endpoint of cardiovascular death or MI. Using IPW adjustment to propensity for agent in a model with stress agent, summed stress score (SSS) remained a significant predictor of the composite endpoint of cardiovascular death or MI (HR 1.36 CI 1.28-1.46; P < .0001) as well as cardiovascular death (HR 1.38 CI 1.28-1.49; P < .0001). The interaction of SSS with agent was not significant. Similar findings were seen with summed difference score (SDS).

CONCLUSIONS

SSS derived from either adenosine or regadenoson SPECT MPI is a significant predictor of events and provides incremental prognostic information beyond basic clinical variables. We have shown for the first time that use of regadenoson vs adenosine as stress agent does not modify the prognostic significance of SSS. Similar findings were seen with SDS.

The Prevalence of Clinically Significant Ischemia in Patients Undergoing Percutaneous Coronary Intervention: A Report from the Multicenter Registry

Background

Myocardial perfusion scintigraphy (MPS) plays an important role in the evaluation and quantification of myocardial ischemia, and those with significant ischemia (SI) benefit most from revascularization procedures. This study aimed to identify the clinical factors and anatomical features associated with SI in patients with stable ischemic heart disease (SIHD).

Methods and Results

Data were analyzed from 4197 SIHD patients undergoing percutaneous coronary intervention (PCI). Ischemia was based on MPS findings prior to PCI, with SI defined as an ischemic region of more than 10% of the total left ventricular area. Logistic regression analysis was performed to identify any clinical factors associated with SI. MPS was used to evaluate 1070 (25.5%) patients pre-procedurally. Patients with a history of heart failure, stroke, or anginal symptoms with Canadian Cardiovascular Society class 2 or more were more likely to have SI (odds ratio [OR] 1.63, p = 0.025, OR: 1.85, p = 0.009, and OR: 1.49, p = 0.003, respectively). When angiographic variables were considered, a proximal left anterior descending artery (pLAD) lesion was the sole factor associated with SI (OR: 1.45, p = 0.012). Importantly, those with SI had more in-hospital complications (p = 0.006), most notably post-PCI infarcts (p = 0.008).

Conclusions

Patients’ background data, such as stronger anginal symptoms or a pLAD lesion, were associated with SI. Patients with SI must be treated with PCI to improve their long-term prognosis; however, procedure-related complications happen more frequently in SI patients than in non-SI patients. Physicians must give their full attention when performing the PCI procedure in SI patients to minimize their complication rate.

Role of coronary physiology in the contemporary management of coronary artery disease

Coronary artery disease (CAD) remains the leading cause of death worldwide with approximately 1 in 30 patients with stable CAD experiencing death or acute myocardial infarction each year. The presence and extent of resultant myocardial ischaemia has been shown to confer an increased risk of adverse outcomes. Whilst, optimal medical therapy (OMT) forms the cornerstone of the management of patients with stable CAD, a significant number of patients present with ischaemia refractory to OMT. Historically coronary angiography alone has been used to determine coronary lesion severity in both stable and acute settings. It is increasingly clear that this approach fails to accurately identify the haemodynamic significance of lesions; especially those that are visually “intermediate” in severity. Revascularisation based upon angiographic appearances alone may not reduce coronary events above OMT. Technological advances have enabled the measurement of physiological indices including the fractional flow reserve, the index of microcirculatory resistance and the coronary flow reserve. The integration of these parameters into the routine management of patients presenting to the cardiac catheterization laboratory with CAD represents a critical adjunctive tool in the optimal management of these patients by identifying patients that would most benefit from revascularisation and importantly also highlighting patients that would not gain benefit and therefore reducing the likelihood of adverse outcomes associated with coronary revascularisation. Furthermore, these techniques are applicable to a broad range of patients including those with left main stem disease, proximal coronary disease, diabetes mellitus, previous percutaneous coronary intervention and with previous coronary artery bypass grafting. This review will discuss current concepts relevant to coronary physiology assessment, its role in the management of both stable and acute patients and future applications.

Assessing clinical impact of myocardial perfusion studies: ischemia or other prognostic indicators?

One of the major strengths of nuclear myocardial perfusion imaging (MPI) is the robust prognostic databases from observational studies demonstrating significantly different outcomes in patients with low-risk vs high-risk scans. The severity of the MPI defect can be semi-quantitated using the summed stress score (SSS) and summed difference score (SDS). SSS is more strongly associated with mortality, whereas SDS is the better predictor of subsequent coronary angiography and revascularization. The strength of MPI variables as prognostic indicators decreases when adjusted for prognostically important clinical and stress test variables. Nonetheless, most studies of general patient populations have demonstrated that MPI adds incremental prognostic value to clinical and stress test information. In contrast to these positive results from observational studies, the application of MPI ischemia as a treatment guide in several recent trials (DIAD, WOMEN, COURAGE, BARI 2D, STICH) has largely failed to identify patient subsets with improved outcome. This issue will continue to be investigated in the ongoing PROMISE and ISCHEMIA trials.

Advances in SPECT in evaluating coronary disease

Myocardial perfusion scintigraphy is the longest established of the functional imaging investigations for patients with known or suspected coronary artery disease. This article describes recent technical and clinical advances that are ensuring that the technique remains relevant some 40 years after its first introduction.

Myocardial ischemia is a key factor in the management of stable coronary artery disease

Previous studies demonstrated that coronary revascularization, especially percutaneous coronary intervention (PCI), does not significantly decrease the incidence of cardiac death or myocardial infarction in patients with stable coronary artery disease. Many studies using myocardial perfusion imaging (MPI) showed that, for patients with moderate to severe ischemia, revascularization is the preferred therapy for survival benefit, whereas for patients with no to mild ischemia, medical therapy is the main choice, and revascularization is associated with increased mortality. There is some evidence that revascularization in patients with no or mild ischemia is likely to result in worsened ischemia, which is associated with increased mortality. Studies using fractional flow reserve (FFR) demonstrate that ischemia-guided PCI is superior to angiography-guided PCI, and the presence of ischemia is the key to decision-making for PCI. Complementary use of noninvasive MPI and invasive FFR would be important to compensate for each method's limitations. Recent studies of appropriateness criteria showed that, although PCI in the acute setting and coronary bypass surgery are properly performed in most patients, PCI in the non-acute setting is often inappropriate, and stress testing to identify myocardial ischemia is performed in less than half of patients. Also, some studies suggested that revascularization in an inappropriate setting is not associated with improved prognosis. Taken together, the presence and the extent of myocardial ischemia is a key factor in the management of patients with stable coronary artery disease, and coronary revascularization in the absence of myocardial ischemia is associated with worsened prognosis.

Correlation between transient ischemic dilatation (TID) and coronary artery disease in Saudi male patients

OBJECTIVE

A high transient ischemic dilatation ratio (TID) for the left ventricle (LV) from a gated myocardial perfusion imaging (G-MPI) study is widely believed to be associated with significant coronary artery disease (CAD). We have investigated the relationship between TID and CAD for our male Saudi Arabian patient population.

METHODS

In this retrospective study, all male Saudi Arabian patients who underwent a two-day G-MPI study using Tc99m MIBI during the year 2011 having a TID ⩾ 1.20 were included. Quantitative perfusion and gated parameters were obtained using Cedar Sinai's AutoQuant software version 3.0, 2003, Means of summed stress scores, summed rest scores and summed difference scores (SSS, SRS, SDS, respectively), stress and rest ejection fraction (EF) were calculated. Visual interpretation was performed to classify the perfusion as normal, fixed, mixed (fixed and reversible defects), single reversible or multiple reversible defects. Coronary angiograms were assessed as normal with no CAD, single vessel, two-vessel or three-vessel disease. Correlations between the TID and other parameters were studied using analysis of variance (ANOVA) with IBM-SPSS version 20.

RESULTS

A total of 52 male patients had a high TID of ⩾1.20 (mean 1.30 ± 0.13). Ten patients had a SSS of 0-3 and 16 were classified as normal by visual assessment. Stress EF (mean 50.4 ± 12%) was lower than the rest EF (mean 56.6 ± 12.8%) with the difference being statistically significant (Students paired t-test, p = 0.001). Angiography results were available in 44 patients, 3 having a normal angiogram, 24 having three vessel disease, 7 having two vessel disease and 10 having one vessel disease. Five patients with normal perfusion and SSS = 0-3 had CAD as seen on a coronary angiography. CAD on coronary angiography showed a significant correlation with perfusion abnormalities as assessed by visual interpretation (p = 0.002). TID showed a significantly correlation with both perfusion abnormalities (p = 0.009), as assessed by visual interpretation, and with Summed difference scores, SDS (p = 0.000).

CONCLUSION

A high TID on G-MPI was a very sensitive indicator of significant CAD. In patients with normal perfusion and high TID further workup is warranted.

Preserved coronary flow reserve effectively excludes high-risk coronary artery disease on angiography

Myocardial perfusion imaging has limited sensitivity for the detection of high-risk coronary artery disease (CAD). We tested the hypothesis that a normal coronary flow reserve (CFR) would be helpful for excluding the presence of high-risk CAD on angiography.

METHODS

We studied 290 consecutive patients undergoing (82)Rb PET within 180 d of invasive coronary angiography. High-risk CAD on angiography was defined as 2-vessel disease (≥ 70% stenosis), including the proximal left anterior descending artery; 3-vessel disease; or left main CAD (≥ 50% stenosis). Patients with prior Q wave myocardial infarction, elevated troponin levels between studies, prior coronary artery bypass grafting, a left ventricular ejection fraction of less than 40%, or severe valvular heart disease were excluded.

RESULTS

Fifty-five patients (19%) had high-risk CAD on angiography. As expected, the trade-off between the sensitivity and the specificity of the CFR for identifying high-risk CAD varied substantially depending on the cutoff selected. In multivariable analysis, a binary CFR of less than or equal to 1.93 provided incremental diagnostic information for the identification of high-risk CAD beyond the model with the Duke clinical risk score (>25%), percentage of left ventricular ischemia (>10%), transient ischemic dilation index (>1.07), and change in the left ventricular ejection fraction during stress (<2) (P = 0.0009). In patients with normal or slightly to moderately abnormal results on perfusion scans (<10% of left ventricular mass) during stress (n = 136), a preserved CFR (>1.93) excluded high-risk CAD with a high sensitivity (86%) and a high negative predictive value (97%).

CONCLUSION

A normal CFR has a high negative predictive value for excluding high-risk CAD on angiography. Although an abnormal CFR increases the probability of significant obstructive CAD, it cannot reliably distinguish significant epicardial stenosis from nonobstructive, diffuse atherosclerosis or microvascular dysfunction.

The coronary calcium treadmill test: a new approach to the initial workup of patients with suspected coronary artery disease

Due to the growth of cardiac testing and increasing cost of cardiovascular healthcare, the development of more cost-effective strategies has now become a dominant issue regarding future utilization of cardiac imaging procedures. To that end, we review the potential of combining two relatively inexpensive tests, the coronary artery calcium (CAC) scan and exercise electrocardiography (ECG), as a first-line test for the workup of patients with suspected coronary artery disease (CAD). The CAC scan was initially introduced as a screening test for CAD, based on data indicating that it is a specific marker for atherosclerosis, predicts clinical risk in accordance with the magnitude of CAC, and provides incremental information for prognostic risk compared to more readily available clinical data. However, CAC scores also predict the likelihood of observing myocardial ischemia among patients undergoing exercise myocardial perfusion SPECT imaging. Exercise ECG predicts clinical events according to the ST-segment response and according to functional exercise capacity, with the latter parameter as a stronger predictor of clinical outcomes. Like CAC scores, exercise functional capacity can also be used to predict the likelihood of ischemia since ischemia diminishes proportionally with increasing exercise capacity. Recent work indicates that when patients are designated by Bayesian analyses into low, intermediate, and high likelihood categories for CAD based on clinical data and the response to exercise ECG, the frequency of inducible myocardial ischemia is very low among both low and intermediate CAD likelihood patients who have a CAC score <400. Future studies are needed to investigate what clinical factors might further modify the CAC-ischemia relationship. On the basis of current data, an initial testing strategy that employs the combined calcium treadmill test has the inherent ability to designate a substantial number of intermediate likelihood patients who would not require further testing due to relatively low CAC scores and reasonable functional capacity.

Prediction of cardiovascular events in pre-dialysis chronic kidney disease patients with normal SPECT myocardial perfusion imaging

PURPOSE

Patients with normal stress myocardial perfusion imaging (MPI) results generally have an excellent prognosis with <1% cardiovascular events/year. Chronic kidney disease (CKD) is an established risk factor for cardiovascular events. However, the estimated glomerular filtration rate (eGFR) varies considerably among patients with CKD. We evaluated the prognostic value of eGFR for patients with CKD who did not undergo hemodialysis and had no evidence of coronary artery disease (CAD).

METHODS AND SUBJECTS

Patients with CKD (n=108; 58 males; mean age: 74 years) with no CAD [no previous CAD and normal stress MPI results; summed stress score (SSS) <4] and with no history of hemodialysis were followed-up (mean duration: 24 months). CKD was defined by eGFR of <60 ml/min/1.73 m(2) and/or persistent proteinuria. Cardiovascular events included cardiac death, non-fatal myocardial infarction, and unstable angina.

RESULTS

Cardiovascular events were observed in 8 patients with CKD (7%). The following were determined as significant predictors of these events: age (hazard ratio=1.14; p=0.019), hemoglobin levels (hazard ratio=0.69; p=0.021), eGFR (hazard ratio=0.94; p=0.008), SSS (hazard ratio=2.31; p=0.012), and summed difference score (hazard ratio=2.33; p=0.014).

CONCLUSIONS

Patients with CKD and with no previous CAD and normal stress MPI results (SSS<4) may not exhibit an excellent cardiovascular prognosis. Further, a lower eGFR and stress MPI results may be the predictors of cardiovascular events. Thus, patients with a lower eGFR and/or normal stress MPI results (SSS<4) may require continuous follow-up.

Impact of repeat myocardial revascularization on outcome in patients with silent ischemia after previous revascularization

OBJECTIVES

This study sought to compare the survival of asymptomatic patients with previous revascularization and ischemia, who subsequently underwent repeat revascularization or medical therapy (MT).

BACKGROUND

Coronary artery disease is progressive and recurring; thus, stress myocardial perfusion scintigraphy (MPS) is widely used to identify ischemia in patients with previous revascularization.

METHODS

Of 6,750 patients with previous revascularization undergoing MPS between January 1, 2005, and December 31, 2007, we identified 769 patients (age 67.7 ± 9.5 years; 85% men) who had ischemia and were asymptomatic. A propensity score was developed to express the associations of revascularization. Patients were followed up over a median of 5.7 years (interquartile range: 4.7 to 6.4 years) for all-cause death. A Cox proportional hazards model was used to identify the association of revascularization with all-cause death, with and without adjustment for the propensity score. The model was repeated in propensity-matched groups undergoing MT versus revascularization.

RESULTS

Among 769 patients, 115 (15%) underwent revascularization a median of 13 days (interquartile range: 6 to 31 days) after MPS. There were 142 deaths; mortality with MT and revascularization were 18.3% and 19.1% (p = 0.84). In a Cox proportional hazards model (chi-square test = 89.4) adjusting for baseline characteristics, type of previous revascularization, MPS data, and propensity scores, only age and hypercholesterolemia but not revascularization were associated with mortality. This result was confirmed in a propensity-matched group.

CONCLUSIONS

Asymptomatic patients with previous revascularization and inducible ischemia on MPS realize no survival benefit from repeat revascularization. In this group of post-revascularization patients, an ischemia-based treatment strategy did not alter mortality.

Temporal trends in the frequency of inducible myocardial ischemia during cardiac stress testing: 1991 to 2009

OBJECTIVES

This study sought to assess whether the frequency of inducible myocardial ischemia during stress-rest single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has changed over time.

BACKGROUND

The prevalence of cardiac death and other clinical cardiac events have declined in recent decades, but heretofore no study has examined if there has been a temporal change in the frequency of inducible myocardial ischemia during cardiac stress testing.

METHODS

We assessed 39,515 diagnostic patients undergoing stress-rest MPI between 1991 and 2009. Patients were assessed for change in demographics, clinical symptoms, risk factors, and frequency of abnormal and ischemic SPECT-MPI.

RESULTS

There was a marked progressive decline in the prevalence of abnormal SPECT studies, from 40.9% in 1991 to 8.7% in 2009 (p < 0.001). Similarly, the prevalence of ischemic SPECT-MPI declined, from 29.6% to 5.0% (p < 0.001), as did the prevalence of severe ischemia. The decline of SPECT-MPI abnormality occurred among all age and symptom subgroups, falling to only 2.9% among recent exercising patients without typical angina. We also noted a progressive trend toward performing more pharmacological rather than exercise stress in all age and weight groups, and pharmacological stress was more likely than exercise to be associated with SPECT-MPI abnormality (odds ratio: 1.43, 95% confidence interval: 1.3 to 1.5; p < 0.001).

CONCLUSIONS

Over the past 2 decades, the frequency and severity of abnormal stress SPECT-MPI studies has progressively decreased. Notably, the frequency of abnormal SPECT-MPI is now very low among exercising patients without typical angina. These findings suggest the need for developing more cost-effective strategies for the initial work-up of patients who are presently at low risk for manifesting inducible myocardial ischemia during cardiac imaging procedures.

Predictors of cardiovascular events in hemodialysis patients after stress myocardial perfusion imaging

Cardiovascular prognosis in patients under normal stress myocardial perfusion images (MPI) is generally excellent. However, this is not true for patients with chronic kidney disease (CKD) treated by hemodialysis. This study evaluated prognostic factors of adverse cardiovascular events in hemodialysis patients in whom stress MPI was performed. Pharmacological stress MPI was performed in 88 hemodialysis patients, and we retrospectively followed-up for 26 months. Cardiovascular events included cardiac death, nonfatal myocardial infarction, and unstable angina. Cardiovascular events occurred in 16 patients (18%). Univariate Cox regression analysis revealed that peripheral artery disease (PAD) and parameters of stress MPI were significant predictors of cardiovascular events. Multivariate Cox regression analysis revealed that only PAD (hazard ratio=6.54; P=0.002), and abnormal stress MPI (hazard ratio=8.26; P=0.008) were independent and significant predictors of cardiovascular events. Kaplan-Meier analysis showed better prognosis in patients with normal stress MPI than in patients with abnormal stress MPI (P<0.001, log-rank test). However, in patients with normal stress MPI, cardiovascular events occurred in 10 of the 76 patients (13%). Among patients with normal stress MPI, Kaplan-Meier analysis showed that patients with no PAD had better prognosis than patients with PAD (P=0.001, log-rank test). In hemodialysis patients, both PAD and stress MPI were powerful cardiovascular predictors. Normal stress MPI alone cannot guarantee good prognosis in terms of cardiovascular events. Consideration of PAD may improve the predictive value of stress MPI in some patients.

Influence of mode of stress and coronary risk factor burden upon long-term mortality following normal stress myocardial perfusion single-photon emission computed tomographic imaging

In patients with normal results on stress single-photon emission computed tomographic (SPECT) studies, coronary artery disease risk factors (RFs) and the mode of testing can influence the trajectory of long-term outcomes. Nevertheless, the combined prognostic impact of these commonly assessed factors has heretofore not been considered. In this study, all-cause mortality rates were assessed in 5,762 patients with normal results on stress SPECT studies. Patients were divided according to mode of stress testing, exercise or pharmacologic, and by number of coronary artery disease RFs. Patients were followed for a mean of 8 ± 4.2 years for all-cause mortality. There were 1,051 deaths (18%), with an annualized mortality rate of 2.2% per year. The RF-adjusted event rate was significantly higher for pharmacologic versus exercise SPECT studies (3.6% per year vs 1.2% per year, p <0.0001) and for patients with increasing numbers of coronary artery disease RFs (p <0.0001). Kaplan-Meier survival analysis revealed wide heterogeneity in all-cause mortality rates when RF burden and performance of exercise versus pharmacologic testing were considered, ranging from only 0.8% per year in exercise patients with no RFs to 4.2% per year in pharmacologic patients with ≥2 RFs. Mortality rates in exercise patients with ≥2 RFs were comparable to those in pharmacologic patients with no RFs. In conclusion, long-term outcomes after cardiac stress testing are synergistically and strongly influenced by RF burden and inability to exercise. Given these findings, prospective study is indicated to determine whether enhanced risk categorization that combines the consideration of these 2 factors improves patient counseling and physician risk management among patients manifesting normal results on stress SPECT studies.

Coronary pressure-derived fractional flow reserve in the assessment of coronary artery stenoses

OBJECTIVES

Catheter-based angiography is the reference-standard to establish coronary anatomy. While routinely employed clinically, lumen assessment correlates poorly with physiological measures of ischaemia. Moreover, functional studies to identify and localise ischaemia before elective angiography are often not available. This article reviews fractional flow reserve (FFR) and its role in guiding patient management for patients with a potentially haemodynamic significant coronary lesion.

METHODS

This review discusses the theory, evidence, indications, and limitations of FFR. Also included are emerging non-invasive imaging FFR surrogates currently under evaluation for accuracy with respect to standard FFR.

RESULTS

Coronary pressure-derived fractional flow reserve (FFR) rapidly assesses the haemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterisation laboratory. The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes.

CONCLUSIONS

FFR is an invaluable modality in guiding coronary disease treatment decisions. It is safe, cost-effective and leads to improved patient outcomes. Non-invasive imaging modalities to assess the physiologic significance of CAD are currently being  developed and evaluated.

Combination of myocardial perfusion imaging and coronary artery calcium scanning: potential synergies for improving risk assessment in subjects with suspected coronary artery disease

For many years, the mainstay of noninvasive evaluation of patients suspected of ischemic cardiovascular disease (CVD) centered on the use of myocardial perfusion imaging (MPI). In recent years, the advent of newer modalities such as coronary artery calcium (CAC) scanning, coronary CT angiography, and MRI have broadened the means of assessing cardiac patients for this purpose. Moreover, the advent of these newer modalities has created potential synergies whereby combinations of tests may be clinically useful. In this review, we assess the potential synergies between MPI, whether assessed by single photon emission computed tomography (SPECT) or positron emission tomography (PET), and CAC scanning. Whereas MPI has long been used for diagnostic assessment and for risk stratification purposes, the emerging uses of CAC scanning now appear multifold: screening for CVD, triaging patients for diagnostic stress testing, improving risk stratification in patients following stress testing, and enhancing the direct management of patients' CVD risk following CAC scanning. Recent work suggests that CAC scanning may be emerging as the initial test of choice for most asymptomatic patients. The advent of hybrid SPECT-CT and PET-CT scanners may signify an important new opportunity for the combined use of these modalities in the higher-risk asymptomatic patient population.