Gated-SPECT myocardial perfusion imaging and coronary calcium score for evaluation of patients with acute chest pain and a normal or nondiagnostic electrocardiogram

Abstract

Objective 

To assess the ability of rest myocardial perfusion imaging (MPI) to rule out an acute coronary syndrome (ACS) in emergency department patients, as well as to investigate whether there exists a concordance between MPI and coronary calcium.

Materials and methods 

Fifty-five patients with chest pain and a normal or nondiagnostic ECG were included. Clinical follow-up was carried out within 1 year.

Results 

Sixteen patients (29%) showed an abnormal rest MPI, and in 11 (20%) the MPI was equivocal. There was a weak concordance between MPI and coronary arteries calcium score (CACS) (κ: 0.25). Coronary angiogram driven by a positive MPI was performed in 12 patients (23%), resulting in percutaneous coronary intervention in nine cases (75%). A positive MPI (abnormal or equivocal results) was associated with the occurrence of events in the follow-up (χ²=19.961, P<0.0001). For a patient presenting to the emergency department with acute chest pain and a normal or nondiagnostic ECG, with a positive MPI, the relative risk of having events during the first year was 7.5 (95% confidence interval: 2.8–19.2), P<0.05, but with a positive CACS this was 1.77 (95% confidence interval: 0.69–4.56), P=NS. At 1 year 68.6% of patients were free of events.

Conclusion 

Patients presenting with acute chest pain and a low-to-intermediate likelihood of coronary artery disease with a normal rest MPI have a very low probability of cardiac events during the first year. Coronary calcium score was not helpful in risk-stratifying these patients.