Usefulness of automated assessment of nuclear cardiology for prediction of major cardiac events in Japanese patients with known or suspected coronary artery disease: Comparison with conventional visual assessment in a large-scale prognostic study

Spherization indices measured by resting SPECT improve risk stratification in patients with ischemia with non-obstructive coronary artery disease (INOCA)

BACKGROUND

The prevalence of ischemia with non-obstructive coronary artery disease (INOCA) is substantial, but its risk stratification has been suboptimal. Resting SPECT myocardial perfusion imaging (MPI) could provide useful heart information including spherical indices. We aimed to evaluate the prognostic value of spherical indices in individuals with INOCA.

RESULTS

During a median follow-up of 47.2 ± 20.8 months, 49 (17.2%) patients experienced major adverse cardiac events (MACE). Compared to those without MACE, those with MACE had a higher shape index (SI) (0.60 ± 0.07 vs. 0.58 ± 0.06; P = 0.028) and a lower E2 (eccentricity index calculated by the QPS) (0.81 ± 0.05 vs. 0.83 ± 0.04; P = 0.019). MACE event-free survival analysis revealed significant differences in the SI and E2 among all patients (all log-rank P < 0.01). Multivariate Cox analysis showed abnormal SI (HR: 2.73, 95% CI 1.44-5.18, P = 0.002) and E2 (HR: 1.94, 95% CI 1.08-3.48, P = 0.026) were both independent predictors for MACE when they were put into the same model, respectively. The incorporation of the SI into the baseline model demonstrated a significant improvement in the predictive accuracy for MACEs (P = 0.026), whereas E2 did not exhibit a similar improvement (P > 0.05).

CONCLUSION

For patients with INOCA, spherical indices (especially the SI) were associated with long-term MACE, which could be a preferable indicator for risk stratification and prognostic prediction.

Correlation between early revascularization and major cardiac events demonstrated by ischemic myocardium in Japanese patients with stable coronary artery disease

BACKGROUND

There is no report on correlation between early revascularization and the occurrence of major cardiac events (MCEs) except severe heart failure in Japanese patients with stable coronary artery disease (CAD). This study aimed to determine whether early revascularization affected the incidence of MCEs in Japanese patients with stable CAD.

METHODS

We retrospectively investigated 3581 stable CAD patients who underwent rest ²⁰¹Tl and stress ^99mTc-tetrofosmin myocardial perfusion single-photon emission computed tomography (SPECT) and provided three-year-prognostic data. The endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction, and unstable angina pectoris. On the basis of estimated propensity scores, patients who underwent revascularization within the first 60 days after the SPECT and those who did not were matched in a 1:1 ratio (n=450 per group). We compared MCE rates in relation to the amount of ischemic myocardium detected with the SPECT between the two groups.

RESULTS

The overall incidence of MCEs was not significantly different between the early-revascularization and no-early-revascularization groups (6.7% vs. 8.7%, p=0.2598). Nevertheless, the incidence of MCEs in the patients with ≤5% ischemia was significantly higher in the early-revascularization group than in the no-early-revascularization group (5.8% vs. 0.8%, p=0.0226). In contrast, the incidence of MCEs in the patients with >10% ischemia was significantly lower in the early-revascularization group than in the no-early-revascularization group (7.0% vs. 16.8%, p=0.0036). The incidence of MCEs in the patients with 6-10% ischemia, however, was not significantly different between the early-revascularization and no-early-revascularization groups (6.9% vs. 4.1%, p=0.3235).

CONCLUSIONS

Early revascularization possibly leads to the occurrence of MCEs related to the treatment procedure but may be a therapeutic strategy leading to improvement in prognosis in patients with moderate to severe ischemia.

Major cardiac event risk scores estimated with gated myocardial perfusion imaging in Japanese patients with coronary artery disease

BACKGROUND

A Heart Risk Table has been reported as the first risk score based on nuclear cardiology to predict cardiac event rates in Japanese patients. However, there are no risk scores estimating risk of major cardiac events (MCEs) except severe heart failure.

METHODS

We retrospectively investigated 2579 patients with known or suspected coronary artery disease (CAD) who underwent rest (201)Tl and stress (99m)Tc-tetrofosmin myocardial perfusion single photon emission computed tomography between October 2004 and March 2011 and who had data on a 3-year follow-up. The perfusion images were analyzed with 20 segments of a five-point visual scoring model to estimate summed defect scores. The endpoint was the onset of MCEs consisting of cardiac death, non-fatal myocardial infarction and unstable angina pectoris.

RESULTS

During the 3-year follow-up, 171 patients (6.6%) experienced MCEs comprising cardiac death (n=78), non-fatal myocardial infarction (n=30), and unstable angina pectoris (n=63). The multivariate logistic regression analysis indicated age, diabetes, estimated glomerular filtration rate (eGFR), and summed stress scores (SSS) as independent predictors of the MCEs and age, stress ejection fraction, eGFR, and SSS as independent predictors of cardiac death. Those four predictors and coefficients corresponding to them were used to make two different risk equations: MCE risk (%/3 years)=1/{1+Exp[-(-3.176+0.018×age+0.602×diabetes-0.022×eGFR+0.051×SSS)]}×100 and cardiac death risk (%/3 years)=1/{1+Exp[-(-2.602+0.031×age-0.031×eGFR+0.038×SSS-0.029×stress ejection fraction)]}×100.

CONCLUSION

The risk scores obtained from this study are useful to predict MCEs in Japanese patients with CAD and are expected to be useful for management and informed consent of high-risk CAD patients.

Significance of worsening renal function and nuclear cardiology for predicting cardiac death in patients with known or suspected coronary artery disease

BACKGROUND

Estimated glomerular filtration rates (eGFRs) at baseline are useful to determine the severity of renal function and to predict cardiac events. However, no studies aimed to demonstrate significance of eGFRs measured during follow-up and usefulness of combination with nuclear cardiology for prediction of cardiac death in patients with coronary artery disease (CAD).

METHODS

We retrospectively investigated 1739 patients with known/suspected CAD who underwent myocardial perfusion single photon emission computed tomography (SPECT), who had eGFRs measured at baseline and after one year and who underwent a three-year follow-up. The SPECT images were analyzed with the visual scoring model to estimate summed defect scores. Reduction in eGFRs (ΔeGFR) was defined as the difference between eGFRs measured after one year and at baseline. The endpoint of the follow-up was cardiac deaths within three years after the SPECT, which were identified with medical records or responses to posted questionnaires.

RESULTS

Cardiac death was observed in 54 of 1739 patients during the follow-up period (45.6±9.1 months). The multivariate Cox regression analysis showed baseline eGFRs, ΔeGFR, and summed stress scores to be significant independent variables for prediction of cardiac death. The area under receiver operating characteristic curves for detection of cardiac death was 0.677 for the baseline eGFR and 0.802 for the follow-up eGFR. Sensitivity of detection of cardiac death was significantly higher in the follow-up eGFR than in the baseline eGFR (p=0.0002). Combination of the best cut-off values, i.e. 9 for the summed stress scores and 10 for the ΔeGFR, which were suggested by receiver operating characteristic analysis, was useful for risk stratification of cardiac death both in patients with and without chronic kidney disease.

CONCLUSION

Baseline and follow-up eGFRs as well as nuclear variables are useful to predict cardiac death in patients with known/suspected CAD.