Electron beam tomography comparison of culprit and non-culprit coronary arteries in patients with acute myocardial infarction

Clinical and angiographic profile of patients with markedly elevated coronary calcium scores (≥1000) detected by electron beam computed tomography

OBJECTIVE

The objective of this study was to determine the clinical and angiographic profile of patients with extremely high coronary artery calcium scores (CACS; >or=1000) by electron beam computed tomography (EBCT).

METHODS

All patients at Rush University Medical Center who had a calcium score >or=1000 and a coronary angiogram performed from 1997 to 2002 were identified using a prospectively collected database. The baseline demographics, symptom status, and degree of coronary stenosis by angiography and subsequent rate of coronary intervention were compared with that of patients with calcium scores <1000.

RESULTS

The clinical and angiographic profile of patients with severe coronary calcification, detected by EBCT, revealed that patients with scores >or=1000 had a significantly higher prevalence of coronary stenosis >or=50% compared with patients with scores <1000 (97% vs. 57%, P<.001). The group with CACS >or=1000 was more likely to be male (90% vs. 75%, P=.027) and was older (64+/-8 vs. 59+/-10, P=.001) compared with the group with less severe calcification. Although there was a significantly higher rate of luminal stenosis detected by coronary angiography in the cohort with CACS >or=1000, there was no difference in subsequent percutaneous coronary intervention (PCI) and utilization of intracoronary stents between the two groups.

CONCLUSIONS

A markedly elevated coronary calcium score (>or=1000) is correlated with increasing age and is associated with an increased likelihood of coronary stenosis >or=50%. However, the decision to perform coronary angiography in patients with severe coronary calcification should not be based solely on these findings, but should remain primarily dependent on the degree of ischemia detected by clinical and functional assessment.

Coronary calcifications in young patients with first, unheralded myocardial infarction: a risk factor matched analysis by electron beam tomography

OBJECTIVE

To compare the presence and extent of coronary calcifications in young patients with first, unheralded acute myocardial infarction with matched controls without a history of coronary artery disease.

METHODS

In 102 patients under 60 years of age (19-59 years, mean 41 years; 88% male), electron beam tomography was done 1-14 days after acute myocardial infarction, before any coronary intervention. Coronary calcifications were quantified using the Agatston score. Age related calcium centiles were determined based on the Mayo Clinic "epidemiology of coronary calcification" study, and results were compared with a group of 102 controls without coronary artery disease, matched for sex, age, and risk factors.

RESULTS

Calcifications were present in 95.1% of patients with acute myocardial infarction and in 59.1% of controls (p = 0.008). The mean (SD) Agatston score was 529 (901) in the infarct patients versus 119 (213) in the controls (p < 0.001). An Agatston score above the 50th centile was present in 87.2% of infarct patients and 47.0% of controls (p = 0.006), and above the 90th centile in 60.7% of infarct patients and only 5.8% of controls (p = 0.001).

CONCLUSIONS

In young patients with their first, unheralded acute myocardial infarction, the presence and extent of coronary calcium are significantly greater than in matched controls.

Coronary calcification compared in patients with acute versus in those with chronic coronary events by using dual-sector spiral CT

PURPOSE

To compare underlying calcific atherosclerotic lesions in acute versus chronic coronary events in patients with hypertension by using dual-sector spiral computed tomography (CT).

MATERIALS AND METHODS

Eight hundred eighty-four calcific lesions were analyzed in a cohort of 50 patients (39 men, 11 women; age range, 55-79 years; mean age, 66 years +/- 6 [SD]) with hypertension who sustained a coronary event during 3-year follow-up. All underwent dual-sector spiral CT within 12 months before the event. Twenty-nine patients had an acute event (acute group): acute myocardial infarction, 20; unstable angina pectoris, six; acute ischemia, two; sudden death, one. Twenty-one patients had chronic manifestations of obstructive coronary disease (chronic group): severe stable angina, five; angiographically identified disease, 12; disease requiring angioplasty, two; and disease requiring bypass surgery, two. To examine differences between the two study groups, the chi(2) or Fisher exact test was applied to categorical parameters and the two-sample t test or Wilcoxon rank sum test to quantitative parameters.

RESULTS

High prevalence of coronary calcium (total coronary calcium score [TCS] >0) was observed in both groups: 93% (27 of 29) in the acute and 95% (20 of 21) in the chronic group. There were 518 lesions in the chronic and 366 in the acute group, with a median number of 35 and nine lesions per patient, respectively (P <.001). The median TCS was 906 for the chronic and 63 for the acute group (P <.01).

CONCLUSION

A mild degree of calcification characterizes patients with acute coronary events, while diffuse high-attenuation calcific plaques are associated with chronic coronary events.

High coronary artery calcium scores pose an extremely elevated risk for hard events

OBJECTIVES

We sought to assess the natural history of a cohort of asymptomatic individuals with very high (> or = 1,000) calcium scores (CSs) on a screening electron beam tomography (EBT) not submitted to further testing after the initial scan. We also compared the outcome of our prospective cohort with that of historical controls with severe abnormalities on myocardial perfusion imaging (MPI).

BACKGROUND

Coronary calcium detected on EBT imaging has been shown to correlate with the total plaque burden. However, there is still controversy as to the prognostic significance of calcium, as some investigators believe that the presence of coronary calcification may stabilize the atherosclerotic plaque.

METHODS

Ninety-eight asymptomatic subjects (mean age: 62 +/- 10) were followed for an average of 17 +/- 11 months (range: 4 to 36 months) after undergoing EBT screening for the occurrence of hard coronary events (HCEs), defined as myocardial infarction or coronary death. All patients had an initial CS > or = 1,000, and in none did the results of the EBT screening lead to further invasive or non-invasive testing.

RESULTS

During the follow-up period, 35 patients (36%) suffered an HCE. All events were recorded in the first 28 months of follow-up. Subjects with HCEs had higher initial CSs than subjects not suffering HCEs (1,561 +/- 270 vs. 1,199 +/- 200, p < 0.001). The annualized event rate in subjects with a CS > or = 1,000 was significantly greater than that of historical controls with severe perfusion abnormalities on MPI (25% vs. 7.4%, respectively; p < 0.0001).

CONCLUSIONS

A high CS (> or = 1,000) on a screening EBT in an asymptomatic person portends a very high risk of an HCE in the short term. This risk appears to be greater than the risk associated with a severe perfusion abnormality on MPI.