Comparative roles of cardiac CT and myocardial perfusion scintigraphy in the evaluation of patients with coronary artery disease: competitive or complementary

Cardiac outcomes 3 years after screening for asymptomatic coronary artery disease in patients with type 2 diabetes: value of myocardial perfusion imaging and coronary calcium score

OBJECTIVE

The aim of the study was to identify the possible association among myocardial perfusion imaging (MPI) variables, coronary calcium score (CCS), and adverse events at medium term in type 2 asymptomatic diabetes mellitus patients.

MATERIALS AND METHODS

Patients who participated in a first study that included a stress-rest MPI and a CCS assessment were asked to take part in this study. The present study protocol required a control single-photon emission computerized tomography after 3 years. Forty-one patients gave their informed consent.

RESULTS

Of the 41 patients, 13 (32%) showed perfusion defects at the initial MPI. Of them, at 3 years, five continued showing perfusion defects, whereas another two had new defects (incidence of ischemia of 17%). Thus, 61% of the initial positive MPIs were normal at 3 years (P=0.04). In these cases the therapy was modified between the two studies. Left ventricular ejection fraction at stress showed a slight increase at 3 years (P=NS). Ventricular volumes significantly decreased at 3 years (P<0.01). Three patients (7.3%) developed an event during the follow-up (FU): two noncardiac deaths and one non-ST elevation myocardial infarction. The only variables that showed a possible association with the occurrence of events at FU were a CCS higher than 100 and less than 5 metabolic equivalents (METS) reached during the stress test (P=0.01).

CONCLUSION

A CCS higher than 100 and a low functional capacity (<5 METS), but not an abnormal MPI, can be associated with cardiac events at 3-year FU in asymptomatic type 2 diabetic patients.

Comparative Analysis between SPECT Myocardial Perfusion Imaging and CT Coronary Angiography for Diagnosis of Coronary Artery Disease

The study aims to discuss the relationship and difference between myocardial perfusion imaging (MPI) using SPECT and CT coronary angiography (CTCA) for diagnosis of coronary artery disease (CAD). Five hundred and four cases undergoing MPI and CTCA were comparatively analyzed, including fifty six patients undergoing invasive coronary angiography in the same period. Among patients with negative MPI results, negative or positive CTCA occupied 84.7% or 15.3%, respectively. Among patients with positive MPI, positive or negative CTCA occupied 67.2% or 32.8%, respectively. Among patients with negative CTCA, negative or positive MPI occupied 94.4% or 5.6%, respectively. Among patients with positive CTCA, positive or negative MPI occupied 40.2% or 59.8%, respectively. Negative predictive value was relatively higher than the positive predictive value for positive CTCA eliminating or predicting abnormal haemodynamics. And there was no significant difference for sensitivity, specificity, and accuracy of MPI or CTCA in diagnosing CAD. Both MPI and CTCA have good diagnostic performance for CAD. They provide different and complementary information for diagnosis and evaluation of CAD, namely, detection of ischemia versus detection of atherosclerosis, which are quite different but have a definite internal link for each other.

Severity of inducible myocardial ischemia predicts incident acute coronary syndromes in asymptomatic individuals with a family history of premature coronary artery disease

BACKGROUND

Although the severity of inducible ischemia provides incremental prognostic information in persons with known or suspected coronary artery disease (CAD), its significance for predicting long-term CAD outcomes in apparently healthy populations is unknown. This study was designed to evaluate the presence and degree of myocardial ischemia in asymptomatic siblings of persons with premature CAD <60 years of age and to determine its significance for predicting incident acute coronary syndromes (ACS) during follow-up of 5 to 25 years.

METHODS

Siblings (n = 1,287, age 30-59 years, 55% female) were screened for traditional risk factors, underwent exercise treadmill testing with nuclear perfusion imaging, and were followed for the development of ACS (mean follow-up 11.6 ± 5.1 years). The severity of ischemia was assessed by semiquantitative methods using the standard 17-segment model and then categorized by the percent maximal summed stress score as none (0%), minimal (1% to <5%), mild (5% to 10%), moderate (10% to 15%), or severe (≥15%).

RESULTS

ACS occurred in 132 subjects (10.3%) and included sudden cardiac death (n = 13), acute MI (n = 62), and unstable angina with revascularization (n = 57). The presence of no (88%), minimal (6%), mild (5%), and moderate/severe (1%) ischemia was associated with an ACS incidence of 8.3%, 19.7%, 25.0%, and 38.9%, respectively (P < .0001 for trend). Kaplan-Meier event-free survival analyses by myocardial ischemia severity categories showed that even minimal and mild myocardial ischemia were associated with greater ACS incidence detectable as early as 2 years after baseline. A Cox proportional hazard model, adjusted for risk factors and follow-up time, showed that each 5% increment in the severity of ischemia resulted in a 77% increase in the hazard of incident ACS (P < .001).

CONCLUSION

Inducible myocardial ischemia is prevalent in asymptomatic siblings of persons with early onset CAD. Most ischemia is minimal or mild in severity, and although the severity of ischemia is associated with the risk of ACS in a graded fashion, the presence of even minimal and mild perfusion defects predicts worse CAD outcomes in this population.

Interrelationship between myocardial perfusion imaging, coronary calcium score, and endothelial function in asymptomatic diabetics and controls

BACKGROUND

Coronary artery disease is a leading cause of death among diabetics, and silent ischemia is a major concern in patients with diabetes mellitus (DM).

METHODS

To detect the prevalence of ischemia in diabetics by myocardial perfusion imaging (MPI), and compare it to a control group without DM but with coronary risk factors, as well as to explore the relationship between silent ischemia, endothelial dysfunction, and coronary calcium, 59 patients (Group I) and 42 controls (Group II) were included. All underwent clinical and laboratory evaluations, gated MPI, brachial artery vasodilation measured by ultrasonography, and coronary calcium score (CCS).

RESULTS

Twenty diabetics showed perfusion defects, vs seven controls (P = .04). There was no significant difference between both groups regarding the brachial artery vasodilator responsiveness: 4.49% ± 4.26% (diabetics) vs 4.70% ± 4.98% (controls). Mean CCS was 74 in diabetics vs five in controls (P = .01). The only risk factor significantly associated with an abnormal MPI was the presence of diabetes (P = .03). In the whole population of patients and in diabetics, the abnormal endothelium-dependent vasodilation, the CCS >100, and the cholesterol/HDL ratio >4, showed an OR >1. CCS exhibited the higher OR among the whole population: OR 2.15 [95% CI 0.42-10.99]; while for diabetics it was the cholesterol/HDL ratio: OR 3.95 [95% CI 0.71-21.84].

CONCLUSIONS

Reversible perfusion defects and coronary calcium are more frequent in diabetics. CCS, abnormal endothelium-dependent vasodilation, and cholesterol/HDL ratio higher than 4, showed an association with perfusion abnormalities in asymptomatic diabetics.