Coronary calcium score correlates with estimate of total plaque burden

Genetic variants in cardiac calcification in Northern Sweden

Extensive coronary calcification without significant stenosis, described as calcific coronary artery disease (CCAD) may cause abnormal myocardial perfusion and hence generalized ischemia. There is a discrepancy in the expression pattern of CCAD compared to the well-known atherosclerotic disease which raises questions about the exact pathophysiology of coronary calcification and whether there is a genetic etiology for it.In this pilot study we studied 3 candidate genes, ectonucleotide pyrophosphatase/phosphodiesterase (ENPP1), ATP Binding Cassette Subfamily C Member 6 (ABCC6), and 5'-Nucleotidase Ecto (NT5E) involved in pyrophosphate (PPi) and inorganic phosphate (Pi) metabolism, which may predispose to coronary arterial or valvular calcification. We studied 70 patients with calcific cardiac disease; 65 with CCAD (age 43-83 years) and 5 with calcific aortic valve disease (CAVD) (age 76-82 years).Five DNA variants potentially affecting protein function were found in 6 patients. One variant is a known disease-causing mutation in the ABCC6 gene. Our findings support that disturbances in the PPi and Pi metabolism might influence the development of CCAD and CAVD. However, segregation in the families must first be performed to ascertain any damaging effect of these variants we have found.We report 4 new genetic variants potentially related to coronary calcification, through the disturbed Pi and PPi metabolism. The search for direct causative genetic variants in coronary artery and aortic valve calcification must be broadened with other genes particularly those involved with Pi and PPi metabolism.

Coronary calcification compromises myocardial perfusion irrespective of luminal stenosis

Aim

The aim of this study was to evaluate the relationship between coronary artery calcification (CAC) assessed by multi-detector computed tomography (MDCT) and myocardial perfusion assessed by cardiac magnetic resonance imaging (CMR) in a group of symptomatic patients.

Method

Retrospective analysis of 120 patients (age 65.1 ± 8.9 years, 88 males) who presented with atypical chest pain to Bethanien Hospital, Frankfurt, Germany, between 2007 and 2010 and who underwent CAC scoring using MDCT, CMR, and conventional coronary angiography. Patients were divided into those with high-grade (HG) stenosis (n = 67, age 65.1 ± 9.4 years) and those with no-HG stenosis (n = 53, age 65.1 ± 8.6 years).

Results

There were more males with HG stenosis (82.1% vs. 62.3%, p = 0.015), in whom the percentage and number of abnormal perfusion segments were higher at rest (37.3% vs. 17%, p = 0.014) but not different with stress (p = 0.83) from those with no-HG stenosis. Thirty-four patients had myocardial perfusion abnormalities at rest and 26 patients developed perfusion defects with stress. Stress-induced myocardial perfusion defects were 22.4% sensitive and 79.2% specific for detecting HG stenosis. The CAC score was lower in patients with no-HG stenosis compared to those with HG stenosis (p < 0.0001). On the ROC curve, a CAC score of 293 had a sensitivity of 71.6% and specificity of 83% in predicting HG stenosis [(AUC 0.80 (p < 0.0001)]. A CAC score of 293 or the presence of at least 1 segment myocardial perfusion abnormality was 74.6% sensitive and 71.7% specific in detecting HG stenosis, the respective values for the 2 abnormalities combined being 19.4% and 90.6%. The severity of CAC correlated with the extent of myocardial perfusion in the patient group as a whole with stress (r = 0.22, p = 0.015), particularly in those with no-HG stenosis (r = 0.31, p = 0.022). A CAC score of 293 was 31.6% sensitive and 87.3% specific in detecting myocardial perfusion abnormalities.

Conclusion

In a group of patients with exertional angina, coronary calcification is more accurate in detecting high-grade luminal stenosis than myocardial perfusion defects. In addition, in patients with no stenosis, the incremental relationship between coronary calcium score and the extent of myocardial perfusion suggests coronary wall hardening as an additional mechanism for stress-induced angina other than luminal narrowing. These preliminary findings might have a clinical impact on management strategies of these patients other than conventional therapy.

Atherosclerotic Calcification Detection: A Comparative Study of Carotid Ultrasound and Cone Beam CT

BACKGROUND AND AIM

Arterial calcification is often detected on ultrasound examination but its diagnostic accuracy is not well validated. The aim of this study was to determine the accuracy of carotid ultrasound B mode findings in detecting atherosclerotic calcification quantified by cone beam computed tomography (CBCT).

METHODS

We analyzed 94 carotid arteries, from 88 patients (mean age 70 ± 7 years, 33% females), who underwent pre-endarterectomy ultrasound examination. Plaques with high echogenic nodules and posterior shadowing were considered calcified. After surgery, the excised plaques were examined using CBCT, from which the calcification volume (mm3) was calculated. In cases with multiple calcifications the largest calcification nodule volume was used to represent the plaque. Carotid artery calcification by the two imaging techniques was compared using conventional correlations.

RESULTS

Carotid ultrasound was highly accurate in detecting the presence of calcification; with a sensitivity of 88.2%. Based on the quartile ranges of calcification volumes measured by CBCT we have divided plaque calcification into four groups: <8; 8-35; 36-70 and >70 mm3. Calcification volumes ≥8 were accurately detectable by ultrasound with a sensitivity of 96%. Of the 21 plaques with <8 mm3 calcification volume; only 13 were detected by ultrasound; resulting in a sensitivity of 62%. There was no difference in the volume of calcification between symptomatic and asymptomatic patients.

CONCLUSION

Carotid ultrasound is highly accurate in detecting the presence of calcified atherosclerotic lesions of volume ≥8 mm3; but less accurate in detecting smaller volume calcified plaques. Further development of ultrasound techniques should allow better detection of early arterial calcification.