Prognostic value of myocardial perfusion-gated SPECT in patients with ischemic cardiomyopathy

Usefulness of the Vall d'Hebron Risk Score to stratify the risk of patients with ischemic cardiomyopathy

BACKGROUND

To evaluate the Vall d'Hebron-Risk-Score (VH-RS) to stratify the risk of patients with stable ischemic cardiomyopathy (ICM), and assess whether hemoglobin (Hb) and estimated glomerular filtration rate (eGFR) provide additional information to the VH-RS.

METHODS AND RESULTS

We analysed 673 consecutive patients with ICM who underwent gated SPECT. According to VH-RS, we stratified patients into 4-risk-levels: very-low-risk (VLR), low-risk (LR), moderate-risk (MR), and high-risk (HRi). We considered as MACEs: non-fatal myocardial infarction (MI), heart failure hospitalization (HF), coronary revascularization (CR), and cardiac death (CD). Also the cardiac-resynchronization-therapy (CRT), and the implantable-cardioverter-defibrillator (ICD) were investigated. During the follow-up (4.8 ± 2.7 years), 379 patients had MACEs (0.18/patient/year). There were no patients in VLR and LR. All patients were reclassified in 3-risk-levels (MRi = 48; HRi = 121; VHRi[very high risk] = 504). Most patients with MACEs were in VHRi level (test-for-trend: MACEs ≥ 1 without CRT/ICD, P < .001; combined non-fatal MI, CD and CR, P < .001; MACEs ≥ 1 with CRT/ICD, P < .001). The Hb and eGFR values do not properly improve the risk stratification obtained by the VH-RS (global-NRI[net-reclassification-improvement] was: (MACEs ≥ 1 without CRT/ICD: - 10.6%; non-fatal MI, CD and CR: - 9.08%; and MACEs ≥ 1 with CRT/ICD: - 8.85%).

CONCLUSION

VH-RS is effective in evaluating risk of patients with stable ICM. In our population, adding Hb and eGFR variables do not improve the performance of the VH-RS.

Development of a risk score for patients with ischaemic cardiomyopathy

BACKGROUND

Ischaemic cardiomyopathy is a leading cause of heart failure and is associated with a poor prognosis.

AIM

To evaluate predictors of major adverse cardiovascular events (MACE) and to develop a risk score for the disease.

METHODS

All patients with ischaemic cardiomyopathy referred to a tertiary hospital between 2010 and 2018 for stress-rest gated single-photon emission computed tomography (SPECT) were included retrospectively (n=747). Clinical and gated SPECT-derived variables were analysed as predictors of MACE, a combined endpoint of cardiovascular mortality, heart failure hospitalization or myocardial infarction during follow-up. A multivariable Cox model using backwards stepwise regression with competing risks was used to select the best parsimonious model.

RESULTS

After a median follow-up of 4.7 years, 313 patients had MACE (41.9%). Independent predictors of MACE were previous heart failure admission, worsening angina or dyspnoea, estimated glomerular filtration rate ≤60mL/min/1.73 m², age>73 years, diabetes, atrial fibrillation, end-diastolic volume index>83mL/m² and>12% of scarred myocardium. A risk score ranging from 0 to 12 classified patients as at intermediate risk (event rate of 4.0 MACE per 100 person-years), high risk (11.3 MACE per 100 person-years) or very high risk (27.8 MACE per 100 person-years). The internally validated area under the curve was 0.720 (95% confidence interval 0.660-0.740) and calibration was adequate (Hosmer-Lemeshow test P=0.28) for MACE.

CONCLUSIONS

In patients with ischaemic cardiomyopathy, a simple risk score using dichotomic and readily available variables obtained from clinical assessment and gated SPECT accurately predicts the risk of MACE.

Novel Imaging Techniques for Heart Failure

Imaging techniques play a main role in heart failure (HF) diagnosis, assessment of aetiology and treatment guidance. Echocardiography is the method of choice for its availability, cost and it provides most of the information required for the management and follow up of HF patients. Other non-invasive cardiac imaging modalities, such as cardiovascular magnetic resonance (CMR), nuclear imaging-positron emission tomography (PET) and single-photon emission computed tomography (SPECT) and computed tomography (CT) could provide additional aetiological, prognostic and therapeutic information, especially in selected populations. This article reviews current indications and possible future applications of imaging modalities to improve the management of HF patients.

Stress Testing After Complete and Successful Coronary Revascularization

BACKGROUND

Noninvasive stress tests play a determinant role in the initial management of patients with chronic angina. Nonetheless, their use in the same patient population is considered inappropriate within 2 years after percutaneous coronary intervention (PCI). Indeed, early abnormal results correlate less well with angiographic control and are attributed to a number of confounding factors. We prospectively assessed prevalence and impact on the quality of life of abnormal stress test results in a highly selected patient population.

METHODS

Patients with no cardiac comorbidities who underwent successful and complete PCI with stenting for typical angina and had an abnormal exercise stress test (EST) under guideline-directed medical treatment were administered the Seattle Angina Questionnaire (SAQ). Clinical evaluation, EST, and the SAQ were repeated at 1, 6, and 12 months after the index PCI.

RESULTS

One hundred ninety-eight patients qualified and were included in the study (mean age, 64 years; 79% men). Although the majority had normal EST results or an increased threshold to angina, at 1 month after the index PCI, 29% of patients still had an abnormal result. At 6 and 12 months, 31% and 29% of patients had abnormal results, respectively. Quality-of-life assessment by the SAQ showed consistent results, with persistent angina in one third of patients. Control angiography documented a critical lesion, attributable to in-stent coronary restenosis, in only 8% of patients.

CONCLUSIONS

When stress testing is systematically performed after PCI, the prevalence of abnormal results is high and is associated with impaired quality of life. Prognostic significance along with the underlying pathophysiological mechanisms of such findings should be investigated.

Gated SPECT myocardial perfusion imaging, intraventricular synchronism, and cardiac events in heart failure

PURPOSE

The purpose of this study was to evaluate the ability of rest gated SPECT myocardial perfusion imaging (MPI) and intraventricular synchronism, to identify heart failure (HF) patients most likely to experience cardiac events.

METHODS

We studied 165 patients with left ventricular ejection fraction of less than 40%, who were divided in 2 groups according to the diagnosis of coronary artery disease (group 1: 136 patients) or not (group 2: 29 patients). All underwent a rest gated SPECT MPI.

RESULTS

In 160 patients, the MPI was abnormal. Mean summed rest score was 17 ± 6 (group 1) versus 10 ± 6 (group 2), P < 0.0001. Mean volumes showed a marked ventricular dilation, slightly higher among nonischemic. The mean value of the phase-derived SD was 70 ± 19 (group 1) versus 59 ± 21 degrees (group 2), P = 0.016. The histogram bandwidth showed no significant differences. Forty-four (39%) of 114 patients showed some kind of event during the follow-up. The more frequent events were HF progression (13%) and acute coronary syndrome (11%). The highest odds ratios for prediction of events were 1.91 (phase SD), 1.66 (etiology), and 1.55 (summed rest score), although the association was not significant.

CONCLUSIONS

A rest gated SPECT is a valid approach to identify HF patients most likely to experience cardiac events.

Gated-SPECT myocardial perfusion imaging as a complementary technique to magnetic resonance imaging in chronic myocardial infarction patients

INTRODUCTION AND OBJECTIVES

The aim of this study was to compare magnetic resonance and gated-SPECT myocardial perfusion imaging in patients with chronic myocardial infarction.

METHODS

Magnetic resonance imaging and gated-SPECT were performed in 104 patients (mean age, 61 [12] years; 87.5% male) with a previous infarction. Left ventricular volumes and ejection fraction and classic late gadolinium enhancement viability criteria (<75% transmurality) were correlated with those of gated-SPECT (uptake >50%) in the 17 segments of the left ventricle. Motion, thickening, and ischemia on SPECT were analyzed in segments showing nonviable tissue or equivocal enhancement features (50%-75% transmurality).

RESULTS

A good correlation was observed between the 2 techniques for volumes, ejection fraction (P<.05), and estimated necrotic mass (P<.01). In total, 82 of 264 segments (31%) with >75% enhancement had >50% single SPECT uptake. Of the 106 equivocal segments on magnetic resonance imaging, 68 (64%) had >50% uptake, 41 (38.7%) had normal motion, 46 (43.4%) had normal thickening, and 17 (16%) had ischemic criteria on SPECT.

CONCLUSIONS

A third of nonviable segments on magnetic resonance imaging showed >50% uptake on SPECT. Gated-SPECT can be useful in the analysis of motion, thickening, and ischemic criteria in segments with questionable viability on magnetic resonance imaging.

Radionuclide imaging in stage B heart failure

This article discusses currently available radionuclide techniques in the diagnostic and prognostic evaluation of patients with chronic heart failure, with a focus on stage B/asymptomatic left ventricular dysfunction. Radionuclide imaging is promising for such patients because it can simultaneously determine left ventricular function, evaluate for the presence of obstructive coronary disease, determine the extent of viable myocardium, and evaluate dyssynchronous left ventricular contraction. Radionuclide imaging can thus provide important noninvasive insights into the pathophysiology, prognosis, and management of patients with asymptomatic left ventricular dysfunction as well as more advanced heat failure.

Usefulness of stress gated technetium-99m single photon emission computed tomographic myocardial perfusion imaging for the prediction of cardiac death in patients with moderate to severe left ventricular systolic dysfunction and suspected coronary artery disease

Although stress gated technetium-99m single-photon emission computed tomographic (SPECT) myocardial perfusion imaging (MPI) is useful in differentiating ischemic from nonischemic cardiomyopathy, its prognostic usefulness in this patient population is not well understood. Consecutive unique patients with suspected coronary artery disease who, for clinical indications, underwent technetium-99m rest and stress MPI demonstrating ejection fractions ≤40% by gated SPECT imaging were retrospectively identified. In addition to prescan variables, previously defined cutoffs for gated SPECT parameters using visual and standard 17-segment semiquantitative scoring were applied and related to the occurrence of cardiac death up to 5 years after MPI. Of the 475 patients fulfilling criteria for study inclusion, follow-up was complete in 444 (93%) over 3.7 ± 1.6 years. Of 393 patients without subsequent early (≤60 days) coronary revascularization, cardiac death occurred in 64 (16%). The summed stress score, an MPI measure of the extent and severity of coronary artery disease that also accounts for the ischemic burden, was the gated SPECT parameter most related to cardiac death with Kaplan-Meier 5-year cardiac death-free survival of 85.6% and 67.3% in patients with summed stress scores ≤8 and >8, respectively (p <0.001). In multivariate Cox regression analysis, a summed stress score >8 independently contributed to cardiac death (adjusted hazard ratio 2.20, 95% confidence interval 1.34 to 3.61), and its addition to the model significantly increased the global chi-square value over prescan variables (from 32.46 to 41.67, p = 0.002). In conclusion, stress MPI data from gated technetium-99m SPECT scans are useful for the prediction of cardiac death in patients with moderate to severe left ventricular systolic dysfunction in whom there is suspicion of underlying coronary artery disease.

[Impact of myocardial perfusion gated-SPECT on the decision to perform coronary angiography in patients with left ventricular dysfunction of ischemic origin]

OBJECTIVES

The aim of this study was to analyze how the myocardial perfusion gated-SPECT (Single Photon Emission Computed Tomography) influences the practice of a coronary angiography in patients with ischemic cardiomyopathy (IM).

PATIENTS AND METHODS

A total of 120 consecutive patients (mean age: 64.9±11.5 years, 25 female) with IM (left ventricular ejection fraction ≤40%) and without previous coronary angiography were evaluated by myocardial perfusion gated-SPECT (96 stress-rest and 24 only at rest). The ventricular ejection fraction (EF) was obtained at rest by gated-SPECT in all patients. The ischemic origin of the systolic dysfunction was established by means of coronary angiography in 64 patients and by previous myocardial infarction in the rest. Gated-SPECT results of these 64 patients were compared with those of 56 patients in whom coronary angiography had not been indicated.

RESULT

Scintigraphic myocardial ischemia (HR: 5.2; CI 95%: 2.68 to 10.35) in patients who were able to perform the stress-rest test) and who had severely impaired EF (<30%) (HR: 0.9; CI 95%: 0.89 to 0.99) were the best independent predictors of coronary angiography. On the contrary, scintigraphic criteria of viability were not a determinant, from the statistical point of view, of coronary angiography in this series.

CONCLUSIONS

In patients with IM, demonstration of ischemia and severe reduction of the EF, but not detection of viable myocardium, prompted the performance of coronary angiography.

Ischemic cardiomyopathy: a clinical nuclear cardiology perspective

Ischemic cardiomyopathy results from severe extensive coronary artery disease, which is associated with left ventricular dysfunction and also, in many cases, with significant left ventricular dilatation. Mortality is high, especially in patients who satisfy myocardial viability criteria but who have not undergone revascularization. Although age, exercise capacity and comorbidity influence survival, the most important prognostic factors are the extent of the ischemia, myocardial viability and left ventricular remodeling, all of which can be successfully evaluated by gated myocardial perfusion single-photon emission computed tomography (SPECT).