Usefulness of exercise test and myocardial perfusion-gated single photon emission computed tomography to improve the prediction of major events

Economic and healthcare resource utilization assessments of PET imaging in Coronary Artery Disease diagnosis: a systematic review and discussion of opportunities for future economic evaluations

AIMS

This systematic literature review (SLR) consolidated economic and healthcare resource utilization (HCRU) evidence for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) to inform future economic evaluations.

MATERIALS AND METHODS

An electronic search was conducted in MEDLINE, Embase, and Cochrane databases from 2012-2022. Economic and HCRU studies in adults who underwent PET- or SPECT-MPI for coronary artery disease (CAD) diagnosis were eligible. A qualitative methodological assessment of existing economic evaluations, HCRU, and downstream cardiac outcomes was completed. Exploratory meta-analyses of clinical outcomes were performed.

RESULTS

The search yielded 13,439 results, with 71 records included. Economic evaluations and comparative clinical trials were limited in number and outcome types (HCRU, downstream cardiac outcomes, and diagnostic performance) assessed. No studies included all outcome types and only one economic evaluation linked diagnostic performance to HCRU. The meta-analyses of comparative studies demonstrated significantly higher rates of early- and late-invasive coronary angiography and revascularization for PET- compared to SPECT-MPI; however, the rate of repeat testing was lower with PET-MPI. The rate of acute myocardial infarction was lower, albeit non-significant with PET- vs. SPECT-MPI.

LIMITATIONS AND CONCLUSIONS

This SLR identified economic and HCRU evaluations following PET- and SPECT-MPI for CAD diagnosis and determined that existing studies do not capture all pertinent outcome parameters or link diagnostic performance to downstream HCRU and cardiac outcomes, thus, resulting in simplified assessments of CAD burden. A limitation of this work relates to heterogeneity in study designs, patient populations, and follow-up times of existing studies. Resultingly, it was challenging to pool data in meta-analyses. Overall, this work provides a foundation for the development of comprehensive economic models for PET- and SPECT-MPI in CAD diagnosis, which should link diagnostic outcomes to HCRU and downstream cardiac events to capture the full CAD scope.

Vall d'Hebron Risk Score II for myocardial infarction and cardiac death

OBJECTIVES

The aim of this study was to create a new Vall d'Hebron Risk Score-II (VH-RS-II) for non-fatal myocardial infarction (MI) and/or cardiac death (CD), excluding patients with coronary revascularisation (CR) during the follow-up.

METHODS

We analysed 5215 consecutive patients underwent gated single photon emission CT (SPECT); 2960 patients (age 64.2±11, male 58.1%) had no previous MI and/or CR, and 2255 patients (age 63.3±11, male 81.9%) had previous MI and/or CR. During a follow-up of 4.3±2.6 years, the cardiac event (MI and CD) was evaluated. This study was reviewed and approved by the ethics committee of our institution (number form trial register, PR(AG)168.2012). To obtain the predictor model, multivariate Cox regression analysis and multivariate logistic regression analysis were used. RS-VH-II was validated with 679 patients.

RESULTS

In patients without previous MI and/or CR, age (HR: 1.01; p<0.001), diabetes (HR: 2.1, p=0.001), metabolic equivalent (METs) (HR: 0.89, p=0.038), ST segment depression (HR: 1.4, p=0.011), ejection fraction (EF) (HR: 0.97, p<0.001) and summed stress score (HR: 1.2, p<0.001) were the independent predictors of CE (C-statistic: 0.8). In patients with previous MI and/or CR, age (HR: 1.06, p<0.001), male (HR: 1.9, p=0.047), smoker (HR: 1.5, p=0.047), METs (HR: 0.8, p<0.001), ST segment depression (HR: 1.4, p=0.002), EF (HR: 0.96; p<0.001) and summed difference score (HR: 1.03, p=0.06) were the independent predictors of CE (C-statistic:0.8).

CONCLUSION

The VH-RS-II obtained from different clinical exercise and gated SPECT variables allow the risk stratification for MI and CD in patients with or without previous MI and/or CR in due form.

Cost-effectiveness of myocardial perfusion SPECT and stress test according to coronary revascularization therapy, cardiac events and total mortality: Register of 8,496 patients

OBJECTIVE

The aim was to analyze the cost-effectiveness ratio (CER) of stress electrocardiogram (ES) and stress myocardial perfusion imaging (SPECT-MPI) according to coronary revascularization (CR) therapy, cardiac events (CE) and total mortality (TM).

MATERIAL AND METHODS

A total of 8,496 consecutive patients who underwent SPECT-MPI were followed-up (mean 5.3±3.5years). Cost-effectiveness for coronary bypass (CABG) or percutaneous CR (PCR) (45.6%/54.4%) according to combined electrocardiographic ischemia and scintigraphic ischemia were evaluated. Effectiveness was evaluated as TM, CE, life-year saved observed (LYSO) and CE-LYSO; costs analyses were conducted from the perspective of the health care payer. A sensitivity analysis was performed considering current CABG/PCR ratios (12%/88%).

RESULTS

When electrocardiogram and SPECT approaches are combined, the cost-effectiveness values for CABG ranged between 112,589€ (electrocardiographic and scintigraphic ischemia) and 2,814,715€ (without ischemia)/event avoided, 38,664 and 2,221,559€/LYSO; for PCR ranged between 18,824€ (electrocardiographic and scintigraphic ischemia) and 46,377€ (without ischemia)/event avoided, 6,464 and 36,604€/LYSO. To CE: the cost-effectiveness values of the CABG and CPR in presence of electrocardiographic and scintigraphic ischemia were 269,904€/CE-avoided and 24,428€/CE-avoided, respectively; and the €/LYSO of the CABG and PCR were 152,488 and 13,801, respectively. The RCE was maintained for the current proportion of revascularized patients (12%/88%).

CONCLUSIONS

Combined ES and SPECT-MPI results, allows differentiation between patient groups, where the PCR and CABG are more cost-effective in different economic frameworks. The major CER in relation to CR, CE and TM occurs in patients with electrocardiographic and scintigraphic ischemia. PCR is more cost-effective than CABG.

A novel clinical risk prediction model for myocardial infarction, coronary revascularization, and cardiac death according to clinical, exercise, and gated SPECT variables (VH-RS)

AIMS

To create a risk score for cardiac events (CE) according to clinical, exercise, and gated SPECT variables.

METHODS AND RESULTS

We analysed 5707 consecutive patients; 3181 patients (age 64.2 ± 11 years, male 59.6%) with suspected coronary artery disease (CAD) [without previous myocardial infarction (MI) or coronary revascularization (CR)] and 2526 patients (age 63.3 ± 11 years, male 81.7%) with established CAD (with previous MI or CR). To create the Vall d'Hebron Risk Score (VH-RS), first we analyse the predictors of CE (non-fatal MI, CR, and/or cardiac death), then the probability of CE for every patient according to the predictive variables. According to risk we stratified patients into four risk levels: very low risk (VLR), low risk (LR), moderate risk (MR), and high risk (HRi) using Multiple Cox Regression analysis models. Finally, we validate the VH-RS in another prospective cohort of 734 patients. In patients with suspected CAD; age (P < 0.001); gender (P = 0.001); hyperlipidaemia (P < 0.001); nitrates (P = 0.04); ejection fraction (EF) (P = 0.001); summed stress score (P < 0.001); METs (P < 0.001); exercise angina (P = 0.006); and mm of ST segment depression (P = 0.004) were the independent predictors of CE (C-statistic: 0.8; P < 0.001). In patients with established CAD, EF (P < 0.001); summed difference score (P = 0.001); age (P < 0.001); smoker (P = 0.002); nitrates (P = 0.003); exercise angina (P = 0.001); METs (P < 0.001); and mm of ST segment depression (P = 0.011) were the independent predictors of CE (C-statistic: 0.7; P < 0.001). The risk score obtained from these variables allows the stratification of patients into four risk levels: VLR, LR, MR, and HRi.

CONCLUSIONS

The cardiac risk stratification by mean of clinical, exercise, and gated SPECT variables is an objective aid to assessing an individual's cardiac risk.

Gender aspects on exercise-induced ECG changes in relation to scintigraphic evidence of myocardial ischaemia

BACKGROUND

This retrospective study aimed to determine the diagnostic performance of exercise-induced ST response in relation to findings by myocardial perfusion single photon emission computed tomography (MPS), with focus on gender differences, in patients with suspected or established stable ischemic heart disease.

METHODS

MPS findings of 1 021 patients (518 females) were related to the exercise-induced ST response alone (blinded and unblinded to gender) and ST response together with additional exercise stress test (EST) variables (exercise capacity, blood pressure and heart rate response).

RESULTS

Exercise-induced ischaemia by MPS was found in 9% of females and 23% of males. Diagnostic performance of exercise-induced ST response in relation to MPS findings in females versus males was: sensitivity = 48%,70%; specificity = 67%, 64%; PPV = 13%, 38%; NPV = 93%, 87%. Adding more EST variables to the ST response interpretation yielded in females vs males: sensitivity = 44%, 51%; specificity = 84%, 83%; PPV = 22%, 48% and NPV = 93%, 85%.

CONCLUSIONS

In patients who have performed EST in conjunction with MPS, there is a gender difference in the diagnostic performance of ST response at stress, with a significantly lower PPV in females compared to males. For both genders, specificity can be significantly improved, and a higher PPV can be obtained, while the sensitivity might be compromised by considering more EST variables, in addition to the ST response.

Coronary Computed Tomography (CT) Angiography as a Predictor of Cardiac and Noncardiac Vascular Events in Asymptomatic Type 2 Diabetics: A 7-Year Population-Based Cohort Study

Background

Type 2 diabetics are at increased risk for vascular events, but the value of further risk stratification for coronary heart disease (CHD) in asymptomatic subjects is unclear. We examined the added value of coronary computed tomography angiography over clinical risk scores (United Kingdom Prospective Diabetes Study), and coronary artery calcium in a population‐based cohort of asymptomatic type 2 diabetics.

Methods and Results

Subjects (n=630) underwent baseline clinical assessment and computed tomography angiography (64‐slice scanner). Plaque site, volume, calcific content, and arterial remodeling were recorded using dedicated software. Coronary, macrovascular, and microvascular‐related events were assessed over 6.6±0.6 (mean±SD) (range 5.4–7.5) years and all CHD events were adjudicated. Discrimination of CHD events (cardiovascular death, myocardial infarction, unstable angina, or new‐onset angina requiring intervention) (n=41) was improved by addition of total plaque burden to the clinical risk and coronary artery calcium scores combined (C=0.789 versus 0.763, P=0.034) and further improved by addition of an angiographic score (C=0.824, P=0.021). Independent predictors of a CHD event were United Kingdom Prospective Diabetes Study risk score (hazard ratio 1.3 per 10% 10‐year risk, P=0.003) and the angiographic score (hazard ratio 3.2 per quartile, P<0.0001). Classification was improved over that by United Kingdom Prospective Diabetes Study and coronary artery calcium scores alone (overall net reclassification improvement 0.24). In subjects with coronary plaque (N=500), mild plaque calcification independently predicted a CHD event (hazard ratio 3.0, P=0.02). Computed tomography angiography predicted combined macrovascular but not microvascular‐related events.

Conclusions

Computed tomography angiography provides additional prognostic information in asymptomatic type 2 diabetics not obtainable from clinical risk assessment and coronary artery calcium alone.

Stress-induced ST elevation with or without concomitant ST depression is predictive of presence, location and amount of myocardial ischemia assessed by myocardial perfusion SPECT, whereas isolated stress-induced ST depression is not

BACKGROUND

Evaluation of stress-induced ST deviations constitutes a central part when interpreting the findings from an exercise test. The aim of this analysis was to assess the pathophysiologic correlate of stress-induced ST elevation and ST depression with regard to presence, amount and location of myocardial ischemia as assessed by myocardial perfusion SPECT (MPS) in patients with suspected coronary artery disease.

METHODS AND RESULTS

226 patients who had undergone bicycle stress test in conjunction with MPS were included. Of these, 198 were consecutive patients while 28 patients were included on the basis of having stress-induced ST elevation mentioned in their clinical report. The amount and location of ST changes were related to MPS findings. Summed stress scores (SSS) from MPS images were used to measure the amount of stress-induced ischemia. The positive predictive values for detecting stress-induced ischemia were 28% for the consecutive patients with ST depression and 75% for patients with ST elevation. The maximum and sum of stress-induced ST elevations correlated with SSS (r(2)=0.58, p<0.001 and r(2)=0.73, p<0.001), whereas the maximum and sum of significant ST depressions did not (r(2)=0.022, p=0.08 and r(2)=0.024, p=0.10). The location of ST elevation corresponded to the location of ischemia by MPS (kappa=1.0), whereas the location of ST depression did not (kappa=0.20).

CONCLUSIONS

Stress-induced ST elevation, with or without concomitant ST depression, is predictive of the presence, amount and location of myocardial ischemia assessed by MPS, whereas stress-induced ST depression without concomitant ST elevation is not.

How should CT coronary angiography be integrated into the management of patients with chest pain and how does this affect outcomes?

When examining the role of a diagnostic test in clinical practice, consideration must be placed not only on the accuracy of the result, but also its impact on patient care and outcomes. Proving a direct effect on outcomes may be difficult because the impact of the diagnostic test largely depends on the clinician's interpretation and consequent actions as well as the patient's response to changes in their diagnosis, investigations, and treatment. Recent major clinical trials of symptomatic patients with suspected coronary heart disease (CHD) have shown that computed tomography coronary angiography (CTCA) can markedly clarify the diagnosis and lead to major changes in patient investigation and management including the use of invasive angiography, preventative therapies, and coronary revascularization. Thus, when added to our existing clinical tools, such as exercise electrocardiography, CTCA represents a powerful method of identifying and excluding CHD. Furthermore, it can identify patients with prognostically relevant non-obstructive CHD and, with recent technological advances, will be able to assess the functional impact of anatomically detected coronary artery stenoses. Overall, the routine integration of CTCA into the investigation of patients with chest pain improves clinical diagnostic certainty that has led to better targeting of investigations and evidence-based treatments that have ultimately translated into improved clinical outcomes.

Plasma B-type natriuretic peptide levels are poorly related to the occurrence of ischemia or ventricular arrhythmias during symptom-limited exercise in low-risk patients

INTRODUCTION

The usefulness of B-type natriuretic peptide (BNP) as a marker of ischemia is controversial. BNP levels have predicted arrhythmias in various settings, but it is unknown whether they are related to exercise-induced ischemic ventricular arrhythmias.

MATERIAL AND METHODS

We analyzed in 63 patients (64 ±14 years, 65% male, 62% with known coronary disease) undergoing exercise stress single-photon emission computed tomography (SPECT) the association between plasma BNP values (before and 15 min after exercise) and the occurrence of ischemia or ventricular arrhythmias during the test.

RESULTS

Exercise test (8.1 ±2.7 min, 7.4 ±8.1 metabolic equivalents, 82 ±12% of maximal predicted heart rate) induced reversible perfusion defects in 23 (36%) patients. Eight (13%) patients presented significant arrhythmias (≥ 7 ventricular premature complexes/min, couplets, or non-sustained ventricular tachycardia during exercise or in the first minute of recovery). Median baseline BNP levels were 17.5 (12.4-66.4) pg/ml in patients developing scintigraphic ischemia and 45.6 (13.2-107.4) pg/ml in those without ischemia (p = 0.137). The BNP levels increased after exercise (34.4 (15.3-65.4)% increment over baseline, p < 0.001), but the magnitude of this increase was not related to SPECT positivity (35.7 (18.8-65.4)% vs. 27.9 (5.6-64.0)% in patients with and without ischemia, respectively, p = 0.304). No significant association was found between BNP values (at baseline or their change during the test) and ventricular arrhythmias.

CONCLUSIONS

Plasma BNP values - at baseline or after exercise - were not associated with myocardial ischemia or with ventricular arrhythmia during exercise SPECT. These results highlight the limited usefulness of this biomarker to assess acute ischemia.

A prognostic scoring system for arm exercise stress testing

Objective

Arm exercise stress testing may be an equivalent or better predictor of mortality outcome than pharmacological stress imaging for the ≥50% for patients unable to perform leg exercise. Thus, our objective was to develop an arm exercise ECG stress test scoring system, analogous to the Duke Treadmill Score, for predicting outcome in these individuals.

Methods

In this retrospective observational cohort study, arm exercise ECG stress tests were performed in 443 consecutive veterans aged 64.1 (11.1) years. (mean (SD)) between 1997 and 2002. From multivariate Cox models, arm exercise scores were developed for prediction of 5-year and 12-year all-cause and cardiovascular mortality and 5-year cardiovascular mortality or myocardial infarction (MI).

Results

Arm exercise capacity in resting metabolic equivalents (METs), 1 min heart rate recovery (HRR) and ST segment depression ≥1 mm were the stress test variables independently associated with all-cause and cardiovascular mortality by step-wise Cox analysis (all p<0.01). A score based on the relation HRR (bpm)+7.3×METs−10.5×ST depression (0=no; 1=yes) prognosticated 5-year cardiovascular mortality with a C-statistic of 0.81 before and 0.88 after adjustment for significant demographic and clinical covariates. Arm exercise scores for the other outcome end points yielded C-statistic values of 0.77–0.79 before and 0.82–0.86 after adjustment for significant covariates versus 0.64–0.72 for best fit pharmacological myocardial perfusion imaging models in a cohort of 1730 veterans who were evaluated over the same time period.

Conclusions

Arm exercise scores, analogous to the Duke Treadmill Score, have good power for prediction of mortality or MI in patients who cannot perform leg exercise.

Cardiovascular mortality prediction in veterans with arm exercise vs pharmacologic myocardial perfusion imaging

BACKGROUND

No data exist comparing outcome prediction from arm exercise vs pharmacologic myocardial perfusion imaging (MPI) stress test variables in patients unable to perform treadmill exercise.

METHODS

In this retrospective study, 2,173 consecutive lower extremity disabled veterans aged 65.4 ± 11.0years (mean ± SD) underwent either pharmacologic MPI (1730 patients) or arm exercise stress tests (443 patients) with MPI (n = 253) or electrocardiography alone (n = 190) between 1997 and 2002. Cox multivariate regression models and reclassification analysis by integrated discrimination improvement (IDI) were used to characterize stress test and MPI predictors of cardiovascular mortality at ≥10-year follow-up after inclusion of significant demographic, clinical, and other variables.

RESULTS

Cardiovascular death occurred in 561 pharmacologic MPI and 102 arm exercise participants. Multivariate-adjusted cardiovascular mortality was predicted by arm exercise resting metabolic equivalents (hazard ratio [HR] 0.52, 95% CI 0.39-0.69, P < .001), 1-minute heart rate recovery (HR 0.61, 95% CI 0.44-0.86, P < .001), and pharmacologic and arm exercise delta (peak-rest) heart rate (both P < .001). Only an abnormal arm exercise MPI prognosticated cardiovascular death by multivariate Cox analysis (HR 1.98, 95% CI 1.04-3.77, P < .05). Arm exercise MPI defect number, type, and size provided IDI over covariates for prediction of cardiovascular mortality (IDI = 0.074-0.097). Only pharmacologic defect size prognosticated cardiovascular mortality (IDI = 0.022).

CONCLUSIONS

Arm exercise capacity, heart rate recovery, and pharmacologic and arm exercise heart rate responses are robust predictors of cardiovascular mortality. Arm exercise MPI results are equivalent and possibly superior to pharmacologic MPI for cardiovascular mortality prediction in patients unable to perform treadmill exercise.

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.

A novel clinically relevant segmentation method and corresponding maximal ischemia score to risk-stratify patients undergoing myocardial perfusion scintigraphy

BACKGROUND

Myocardial perfusion scintigraphy (MPS) represents a key prognostic tool, but its predictive yield is far from perfect. We developed a novel clinically relevant segmentation method and a corresponding maximal ischemia score (MIS) in order to risk-stratify patients undergoing MPS.

METHODS

Patients referred for MPS were identified, excluding those with evidence of myocardial necrosis or prior revascularization. A seven-region segmentation approach was adopted for left ventricular myocardium, with a corresponding MIS distinguishing five groups (no, minimal, mild, moderate, or severe ischemia). The association between MIS and clinical events was assessed at 1 year and at long-term follow-up.

RESULTS

A total of 8,714 patients were included, with a clinical follow-up of 31 ± 20 months. Unadjusted analyses showed that subjects with a higher MIS were significantly different for several baseline and test data, being older, having lower ejection fraction, and achieving lower workloads (P < .05 for all). Adverse outcomes were also more frequent in patients with higher levels of ischemia, including cardiac death, myocardial infarction (MI), and their composites (P < .05 for all). Differences in adverse events remained significant even after extensive multivariable adjustment (hazard ratio for each MIS increment = 1.57 [1.29-1.90], P < .001 for cardiac death; 1.19 [1.04-1.36], P = .013 for MI; 1.23 [1.09-1.39], P = .001 for cardiac death/MI).

CONCLUSIONS

Our novel segmentation method and corresponding MIS efficiently yield satisfactory prognostic information.

Update on cardiac imaging techniques 2013

Cardiac imaging is a cornerstone of diagnosis in heart conditions, and an essential tool for assessing prognosis and establishing treatment decisions. This year, echocardiography stands out as a guide in interventional procedures and in choosing the size of the prosthesis. It is also proving to be a valuable technique in low-flow, low-gradient aortic stenosis. Three-dimensional echocardiography is advancing our knowledge of cardiac anatomy and valvular measurements. The parameters indicating tissue deformation have predictive power in valve disease and in the follow-up of drug-induced cardiotoxicity. Single-photon emission computed tomography and positron emission tomography are proving useful in ischemic heart disease and in the diagnosis of cardiac inflammation and infections. The role of computed tomography has been strengthened in noninvasive coronary angiography, the emergency room management of chest pain, assessment of chronic occlusions, and morphologic study of coronary plaque. Cardiac magnetic resonance imaging remains the gold standard for tissue characterization in ischemic heart disease and cardiomyopathies, and is assuming a greater role in stress studies and in the assessment of myocardial viability.