Elsevier

Journal of Nuclear Cardiology

Volume 14, Issue 5, September–October 2007, Pages 669-679
Journal of Nuclear Cardiology

Original article
Use of coronary calcium scanning for predicting inducible myocardial ischemia: Influence of patients’ clinical presentation

https://doi.org/10.1016/j.nuclcard.2007.07.005Get rights and content

Background

The selection of patients for cardiac stress tests is generally based on assessment of chest pain symptoms, age, gender, and risk factors, but recent data suggest that coronary artery calcium (CAC) measurements can also be used to predict inducible myocardial ischemia. However, the potential influence of clinical factors on the relationship between CAC measurements and inducible ischemia has not yet been investigated.

Methods and Results

We prospectively performed CAC scanning in 648 patients undergoing exercise myocardial perfusion single photon emission computed tomography. The frequency of ischemia on myocardial perfusion single photon emission computed tomography was assessed according to CAC magnitude after dividing patients according to chest pain symptom class and Bayesian likelihood of angiographically significant coronary artery disease (ASCAD). Estimates of ASCAD likelihood and CAC scores were poorly correlated. The frequency of inducible myocardial ischemia was very low among patients with a low ASCAD likelihood if CAC scores were less than 400. By contrast, the threshold for increasing ischemia occurred at low CAC scores among patients with a high ASCAD likelihood. When characterized by chest pain classification, asymptomatic and nonanginal chest pain patients had a low frequency of ischemia if CAC scores were less than 400, whereas lower CAC scores did not exclude ischemia among typical angina or atypical angina patients.

Conclusions

CAC scores predict myocardial ischemia, with a threshold score of greater than 400 among patients with a low likelihood of ASCAD and those who are asymptomatic or have nonanginal chest pain. These data appear to extend the pool of patients for whom CAC scanning may be useful in ascertaining the need for cardiac stress testing.

Section snippets

Study cohort

The study participants comprised 648 patients (mean age, 58 ± 10.6 years; 62% men) who underwent CAC scanning on a prospective research basis (as part of the Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research [EISNER] study), after first undergoing physician-ordered exercise-rest MPS scanning at Cedars-Sinai Medical Center (Los Angeles, Calif), usually because of chest pain symptoms or the presence of coronary risk factors (or both). CAC scanning was performed

Results

The clinical characteristics of our recruited patients are shown in Table 1, divided according to chest pain grouping. Patients who were asymptomatic had the lowest mean likelihood of ASCAD and those with typical angina had the highest mean likelihood of ASCAD before MPS testing, but the chest pain groups did not differ significantly in the distribution and number of CAD risk factors. Exercise duration was lowest and the frequencies of exercise-induced chest pain, ST-segment depression, and MPS

Discussion

Because formation of calcium-containing atherosclerotic plaque generally precedes the development of clinically overt CAD by many years, CAC scanning has been proposed as a means of screening for subclinical atherosclerosis before clinical symptoms become manifest. However, clinical estimates of the likelihood of ASCAD, and not CAC, are most commonly used in judging the appropriateness of patients’ referral for cardiac stress testing.1, 2 To date, comparisons of CAC measurements to ASCAD

Acknowledgment

The authors have indicated they have no financial conflicts of interest.

References (34)

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This study was supported by a grant from The Eisner Foundation, Los Angeles, Calif.

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