Coronary calcifications in the detection of coronary artery disease and comparison with electrocardiographic exercise testing. Results from the National Heart, Lung, and Blood Institute's type II coronary intervention study

Coronary Artery Calcium: Where Do We Stand After Over 3 Decades?

In 2018, cardiovascular society cholesterol guidelines recommended the use of coronary artery calcium to guide statin therapy in patients 40-79 years of age who are at intermediate risk by multiple risk factor equations (ie, estimated 10-year risk for atherosclerotic disease of 7.5%-19.9% but in whom statin benefit is uncertain). Many such patients have no coronary calcium and remain at <5% risk over the next decade; hence, statin therapy can be delayed until a repeat calcium scan is conducted. Exceptions include patients with severe hypercholesterolemia, diabetes, and a strong family history of atherosclerotic disease. If coronary calcium equals 1-99 Agatston units, the 10-year risk is borderline (5% to <7.5%) and statin therapy is optional pending a repeat scan. If coronary calcium equals 100-299 Agatston units, the patient is clearly statin eligible (7.5% to <20% 10-year risk). And finally, if coronary calcium is ≥300 Agatston units, a patient is at high risk and is a candidate for high-intensity statins. Risk factor analysis combined judiciously with coronary calcium scanning offers the strongest evidence-based approach to use of statins in primary prevention.

Relationship between toll-like receptor 4 levels in aorta and severity of atherosclerosis

OBJECTIVE

To investigate the relationship between levels of toll-like receptor 4 (TLR4) protein in aortic tissue and the severity of atherosclerosis in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

Samples of ascending aorta and renal artery were collected from patients undergoing CABG surgery or kidney donation, respectively. TLR4 levels were determined by immunohistochemistry. Coronary angiography was performed to determine atherosclerosis severity via Gensini score.

RESULTS

TLR4 was present at high levels in aortic tissues from patients (n = 46), and was absent from renal artery tissue (controls; n = 11). There was a significant positive correlation between Gensini score and TLR4 level in the patient group.

CONCLUSIONS

TLR4 may play an important role in atherosclerosis and could be a potential therapeutic target for treatment of coronary artery disease. Discarded aortic tissue obtained during CABG surgery provides a new approach to the study of the pathogenesis of atherosclerosis.

Calcifications of the heart

Cardiac calcification usually represents the result of a pathologic process. Some forms of calcification represent chronic change in an ageing population, and must be differentiated from pathologic calcification. Still other forms of calcification are associated with ageing and chronic degeneration, but also reflect ongoing pathologic processes. Recognition of cardiac calcification may be an early sign or only sign of a pathologic process. Characterization of the calcification in terms of its distribution and appearance is a helpful means for determining which structures are calcified, differentiating pathologic from nonpathologic processes. This article provides an overview of the types of calcifications of the heart, pathogenesis, and utility of the various imaging modalities for their detection.

Secondary hyperparathyroidism and its therapy as a cardiovascular risk factor among end-stage renal disease patients

Secondary hyperparathyroidism (HPTH) was initially viewed as a disorder of the skeletal system; however, recent population-based data have associated markers of HPTH with an increased cardiovascular mortality among patients with end-stage renal disease (ESRD). This has stimulated much interest in further evaluating secondary HPTH as a cardiovascular disease risk factor, as well as the putative role of its therapy. This article explores the current state of scientific evidence concerning the pathophysiology of cardiovascular disease among the ESRD population and potential risk factors for its development, including markers of HPTH, and its therapies.

Coronary calcium: the good, the bad, and the uncertain

BACKGROUND

Coronary calcium deposits have been widely regarded to result from a passive process of encrustation or adsorption of mineral onto advanced, complex atherosclerotic lesions. Increasing interest has focused on noninvasive radiologic detection of these calcium deposits as a diagnostic and prognostic adjunct to clinical evaluation of coronary artery disease, particularly with the use of newer, high-resolution imaging techniques such as electron beam computed tomography.

METHODS AND RESULTS

We reviewed the literature on coronary calcium and its relation to pathologic atherosclerosis, angiographic stenoses,and clinical events. Clinical calcium detection studies have demonstrated an association between coronary calcium and both extent of coronary artery disease and risk of adverse events. These studies have in the past tended to reinforce the perception that calcific deposits result from a passive mineralization process, signify advanced coronary artery disease, and foreshadow future coronary events.

CONCLUSIONS

Recent pathologic, genetic, clinical, and biochemical evidence reviewed in this article suggests that coronary calcium deposits are a manifestation of a complex, organized, and regulated process similar in many respects to new bone formation and may not be a reliable indicator of either the extent of coronary disease or the risk of a future event. These studies also suggest that atherosclerosis and calcific deposits may be distinct pathologic entities that frequently occur together and are related to each other in ways that are poorly understood.

Imaging of coronary artery calcification. Its importance in assessing atherosclerotic disease

Coronary artery calcification is a marker for atherosclerotic disease. The calcifications frequently occur early in the disease process and often before the development of luminal narrowing or cardiac events. Electron beam CT has a high accuracy in detecting calcifications, and thus has prognostic value in predicting luminal narrowing and future cardiac events.

Does myocardial thallium-201 SPECT combined with electron beam computed tomography improve the detectability of coronary artery disease?--comparative study of diagnostic accuracy

OBJECTIVE

The aim of this study is to evaluate the diagnostic accuracy of myocardial 201Tl SPECT combined with EBT for detecting CAD.

METHODS

The study was based on 34 patients with suspected CAD, who had EBT and myocardial 201Tl SPECT. The CAD was diagnosed by the findings of coronary arteriography. Sensitivity, specificity and accuracy of EBT, myocardial 201Tl SPECT and the combined diagnosis on a per vessel basis and a per-patient basis were studied.

RESULTS

The sensitivity for detecting CAD of myocardial 201Tl SPECT, EBT and the combined diagnosis was 85%, 77%, and 62%, respectively. No significant difference in the accuracy of myocardial 201Tl SPECT, EBT and the combined diagnosis was observed on a patient basis and per vessel basis. In the over 70 yr age subgroup, the sensitivity and accuracy of EBT for detecting LAD lesion were significantly superior to those of myocardial 201Tl SPECT. Regardless of age-based subgroups and gender, the combined diagnosis did not contribute to an improvement in diagnostic accuracy.

CONCLUSION

Although the sensitivity of EBT for detecting LAD lesion in patients over 70 yr of age was significantly higher than that of myocardial 201Tl SPECT, in the detectability of CAD, combined use of myocardial 201Tl SPECT and EBT offers no improvement.

A comparison of 99mTc-MIBI myocardial SPET with electron beam computed tomography in the assessment of coronary artery disease

We compared technetium-99m methoxyisobutylisonitrile (MIBI) myocardial perfusion single-photon emission tomography (SPET) (MPS) and electron beam computed tomography (EBCT) in order to assess their respective value in the detection of coronary artery disease (CAD). 99mTc-MIBI SPET (stress-resting) and EBCT studies were performed in 51 patients with suspected CAD who underwent coronary angiography (CAG). CAG showed that of the 51 patients, 36 had coronary stenosis >/=50% while 15 had normal results. A moderate positive rank correlation was found between coronary calcification detected by EBCT and MPS score (rs=0.5283, P<0.01). The concordance between EBCT and MPS for the evaluation of CAD was 72.5% (37/51). The sensitivity of EBCT in detecting CAD in 51 patients was comparable to that of MPS (81% vs 94%, NS). However, the accuracy of EBCT was lower than that of MPS (78% vs 94%, P<0.025). As regards the detection of individual coronary artery disease, there was no significant difference in sensitivity between EBCT and MPS (65% vs 75%, NS); however, the specificity and accuracy of EBCT were lower than those of MPS (specificity: 77% vs 95%, P<0.005; accuracy 71% vs 85%, P<0.005). The sensitivity, specificity and accuracy of MPS in detecting single-vessel disease were higher than those of EBCT (sensitivity: 86% vs 42%, P<0.025; specificity: 96% vs 70%, P<0.025; accuracy: 93% vs 61%, P<0.005). However, no significant differences in the sensitivity, specificity and accuracy of MPS and EBCT were found in respect of multivessel disease.

IN CONCLUSION

99mTc-MIBI myocardial perfusion SPET and EBCT provide different information in the assessment of CAD. The sensitivity of EBCT for the detection of CAD is comparable with that of MPS; however, the specificity and accuracy of EBCT are lower than those of MPS. More reliable results will be obtained if both myocardial perfusion SPET and EBCT are performed.

Calcium metabolism, osteoporosis and essential fatty acids: a review

Essential fatty acid (EFA)-deficient animals develop severe osteoporosis coupled with increased renal and arterial calcification. This picture is similar to that seen in osteoporosis in the elderly, where the loss of bone calcium is associated with ectopic calcification of other tissues, particularly the arteries and the kidneys. Recent mortality studies indicate that the ectopic calcification may be considerably more dangerous than the osteoporosis itself, since the great majority of excess deaths in women with osteoporosis are vascular and unrelated to fractures or other bone abnormalities. EFAs have now been shown to increase calcium absorption from the gut, in part by enhancing the effects of vitamin D, to reduce urinary excretion of calcium, to increase calcium deposition in bone and improve bone strength and to enhance the synthesis of bone collagen. These desirable actions are associated with reduced ectopic calcification. The interaction between EFA and calcium metabolism deserves further investigation since it may offer novel approaches to osteoporosis and also to the ectopic calcification associated with osteoporosis which seems to be responsible for so many deaths.

Detection of coronary artery calcium to differentiate patients with early coronary atherosclerosis from luminally normal arteries

Patients with angiographic evidence of early coronary atherosclerosis (<50% diameter stenosis) have a poorer prognosis than those with normal arteries and may benefit from more aggressive interventions targeted toward the primary prevention of cardiovascular disease. Using a calcium score of 5, fast computed tomography was able to identify 59% of patients with early atherosclerosis, while excluding 87% of patients with smooth, luminally normal coronary arteries.

Coronary artery calcium detected by digital fluoroscopy and risk factors in healthy subjects

Coronary artery calcium detected by digital fluoroscopy is closely associated with known risk factors of coronary artery disease in asymptomatic low-risk populations. Even in the absence of significant luminal narrowing, this may not be an innocent finding, and subjects with coronary calcium may be at greater risk for developing obstruction and clinical disease.

Noninvasive prediction of coronary atherosclerosis by quantification of coronary artery calcification using electron beam computed tomography: comparison with electrocardiographic and thallium exercise stress test results

OBJECTIVES

This study was designed to compare the usefulness of electron beam computed tomography for prediction of coronary stenosis with that of electrocardiographic (ECG) and thallium exercise tests.

BACKGROUND

Electron beam computed tomography can quantify coronary calcifications; however, its clinical value has yet to be established.

METHODS

Using the volume mode of electron beam computed tomography, we studied 251 consecutive patients who underwent elective coronary angiography because of suspected coronary artery disease and compared the results with those of ECG and thallium exercise tests. The total coronary calcification score was calculated by multiplying the area ( > or = 2 pixels) of calcification (peak density > or = 130 Hounsfield units) by an arbitrarily weighted density score (0 to 4) based on its peak density. The mean of two scans was log transformed.

RESULTS

Calcification was first noted in women in the 4th decade of life, approximately 10 years later than its occurrence in men. Among patients with advanced atherosclerosis (two- and three-vessel disease), calcification scores were uniformly high in women but ranged widely in men. Nine percent of patients with significant stenoses ( > or = 75% by densitometry) had no calcification. The calcification scores of patients with significant stenosis in at least one vessel were significantly higher than those of patients without significant stenosis in the study group as a whole and in most patient subgroups classified according to age and gender. A cutoff calcification score for prediction of significant stenosis, determined by receiver operating characteristic curve analysis, showed high sensitivity (0.77) and specificity (0.86) in all study patients; sensitivity was similarly high even in older patients ( > or = 70 years) and was enhanced in middle-aged patients (40 to < or = 60 years). The difference in specificity between calcification scores and ECG exercise test results had borderline significance (p = 0.058) and that between calcification scores and thallium test results was significant (p = 0.001). The latter difference became small but remained significant (p = 0.01) even after the reevaluation of thallium test results in light of each subject's clinical data.

CONCLUSIONS

Quantification of coronary artery calcification with electron beam computed tomography noninvasively predicted angiographically confirmed coronary stenosis. Results obtained with this method were at least as useful and potentially better in some patient groups than those obtained with thallium and ECG exercise testing.

Usefulness of cinefluoroscopic detection of coronary artery calcification in the diagnostic work-up of coronary artery disease

AIM

To determine in which patients (cine)fluoroscopic detection of coronary artery calcifications is recommended for the diagnosis of coronary artery disease and the consequence of this finding for referral for cinecoronary arteriography.

MATERIALS AND METHODS

Data were retrospectively obtained from 778 patients who had been referred for cinecoronary arteriography. Excluded were patients with a previous myocardial infarction, a previous abnormal cinecoronary arteriogram and patients with unstable angina. The discriminating value was assessed with the help of the crude likelihood ratio (LR), as well as the LRs stratified for gender, age and symptomatology. The gold standard was the coronary arteriogram. Furthermore, the post-test probability was estimated using logistic regression to take dependence on age, sex and symptomatology into account.

RESULTS

The crude LR of a positive and negative test result, with 95% confidence intervals, was, respectively 5.8 (4.1-8.2) and 0.52 (0.47-0.58), but was dependent on the clinical variables. Estimated probabilities of having coronary artery disease (CAD) varied substantially for a negative as well as a positive test result with the categories of clinical variables.

CONCLUSION

(Cine)fluoroscopy discriminates between patients with and without disease; the test proved to be especially useful in females with atypical angina and patients of both sexes with non-specific chest pain.

Comparison of the diagnostic value of cinefluoroscopy and simple fluoroscopy in the detection of calcification in coronary arteries

AIM

Comparison of the diagnostic value of cinefluoroscopy and simple fluoroscopy in the detection of calcification in coronary arteries.

PATIENTS AND METHODS

Data were prospectively obtained from 143 patients in whom simple fluoroscopy as well as cinecoronary arteriography were performed. Excluded were patients with a previous myocardial infarction, a previous abnormal cinecoronary arteriogram and patients with unstable angina. With the coronary arteriogram as the gold standard, the likelihood ratios (LR) of simple fluoroscopy were determined, mismatches with cinefluoroscopy were analysed and Kappa, as a measure for inter-test agreement, was calculated.

RESULTS

The LRs with 95% confidence intervals for a positive and negative result were 5.3 (2.6-11.0) and 0.43 (0.28-0.69), respectively. There was a mismatch in 12 (8.3%) patients. Kappa with a 95% confidence interval was 0.90 (0.73-1.0).

CONCLUSIONS

Both test modalities are almost identical and conclusions with respect of the diagnostic value of cinefluoroscopy also holds for simple fluoroscopy.

Quantitation of in vitro coronary artery calcium using ultrafast computed tomography

Ultrafast computed tomography (UFCT) has the potential to quantify coronary hydroxyapatite (HAP). However, no definitive studies validating this technique are available. We constructed a human chest phantom model with coronary arteries represented by cylindrical holes containing: (1) calcium chloride solutions, (2) a block of HAP immersed in paraffin (without partial volume effect), and (3) HAP granules embedded in a gelatin matrix (with partial volume effect). We scanned this model to determine the relationship between measured CT number per voxel and density of the calcium per voxel. The relationships between CT number and concentration of calcium chloride was linear (r = 0.992 to 0.999). Using a commercially available standard bone mineral phantom, we were able to estimate the concentration of HAP to an accuracy from 94 to 97% when partial volume effects were absent. However, when partial volume effects were present, two methods of estimating HAP produced significant errors (1 to 384%, and 17 to 52%). We conclude that significant partial voluming errors degrade the accuracy of HAP quantitation and that further evaluation and corrections are needed before such quantitation is clinically applied.

Prognostic significance of cardiac cinefluoroscopy for coronary calcific deposits in asymptomatic high risk subjects

OBJECTIVES

This research investigated the prognostic significance of radiographically detectable coronary calcific deposits.

BACKGROUND

Coronary calcific deposits are almost always associated with coronary atherosclerosis. We investigated the association between fluoroscopically determined coronary calcium and coronary heart disease end points at 1 year of follow-up.

METHODS

This prospective population-based cohort study was conducted in the suburbs of Los Angeles. Fourteen hundred sixty-one asymptomatic adults with an estimated > or = 10% risk of having a coronary heart disease event within 8 years underwent cardiac cinefluoroscopy for assessment of coronary calcium at initiation of the study. Clinical status including angina, documented myocardial infarction, myocardial revascularization and death from coronary heart disease were determined after 1 year.

RESULTS

The prevalence of calcific deposits was high (47%). A follow-up examination at 1 year was successfully completed in 99.9% of subjects. Six subjects (0.4%) had died from coronary heart disease and 9 (0.6%) had had a nonfatal myocardial infarction. Thirty-seven subjects (2.5%) reported angina pectoris, and 13 (0.9%) had undergone myocardial revascularization. Fifty-three subjects had at least one event during the 1-year period. Radiographically detectable calcium was associated with the presence of at least one of these end points, with a risk ratio of 2.7 (confidence limits 1.4, 4.6). The presence of coronary calcium was an independent predictor of at least one end point when controlling for age, gender and risk factors. However, three deaths due to coronary heart disease and two nonfatal myocardial infarctions occurred in subjects without detectable coronary calcium.

CONCLUSIONS

The presence of coronary calcific deposits incurs an increased risk of coronary heart disease events in asymptomatic high risk subjects at 1 year. This increased risk is independent of that incurred by standard risk factors.

Detection and quantitation of calcific atherosclerosis by ultrafast computed tomography in children and young adults with homozygous familial hypercholesterolemia

Ultrafast computed tomography (CT) is a new method for detecting calcific lesions in the coronary arteries. The ability of CT to detect and quantify coronary artery atherosclerosis in children and young adults at risk for malignant atherogenesis was evaluated. A total of 11 consecutive familial hypercholesterolemic (FH) homozygotes (3 to 37 years old) participated. Untreated total cholesterol concentrations were 488 to 1277 mg/dL (12.7 to 33.2 mmol/L). Angiography detected significant lesions in 7 of 11 patients. CT detected calcific atherosclerosis in all 9 of the patients older than 12 years of age, including all those with angina. CT was more sensitive in detecting aortic root and coronary ostial lesions, where atherosclerosis first appears in homozygous FH. The volume of calcification (in cubic millimeters) correlated with the severity and duration of the hypercholesterolemia (r = .62, P < .05) as well as with the presence of angina (P < .05). All patients with angina (7 of 7) had > 150 mm3 of calcified volume, whereas only 1 of 4 asymptomatic patients had a volume score > 150 mm3. We conclude that (1) coronary and aortic calcium phosphate deposits are common in young FH homozygotes; (2) these deposits are associated with the presence of angiographic stenoses, as has been seen in adults with coronary atherosclerosis; and (3) aortic calcific deposits are more common than calcific coronary lesions.

Abnormal exercise electrocardiogram in an asymptomatic person--what next?

No reasonable guidelines exist for evaluating an asymptomatic individual (without evidence for ischemic heart disease on history or electrocardiography) with a positive exercise ECG. Available data indicate that persons with a strongly positive test should undergo a coronary angiography. In persons with mild to moderately positive results, cinefluoroscopy is indicated and those who show coronary calcification should have a coronary angiogram. Although stress thallium-201 is often done before coronary angiography, its role is limited. Scant data exist in women and suggest that the overall approach may not be markedly different. However, ST changes in women have a low specificity. Recent studies indicate a 95% specificity and sensitivity for positron emission tomography. Despite its high costs it may still be the most cost-effective modality by saving unwanted radionuclide studies and arteriographies.

Fluoroscopic coronary artery calcification and associated coronary disease in asymptomatic young men

Little is known about the diagnostic significance of coronary artery calcification detected fluoroscopically in apparently healthy young men. This study compared the presence of fluoroscopically detected coronary artery calcification with angiographic coronary artery disease in asymptomatic male military aircrew undergoing noninvasive cardiac screening tests and coronary arteriography for occupational indications. Of 1,466 men screened with coronary fluoroscopy, 613 underwent coronary arteriography because of one or more abnormal noninvasive test results. The mean age (+/- SD) of all subjects screened was 40.2 +/- 5 years (range 26 to 65). Significant coronary artery disease (greater than or equal to 50% diameter stenosis) was found in 104 of the 613 subjects with arteriograms (16.9% disease prevalence). Overall sensitivity and specificity for coronary artery calcification detection of significant disease, based only on those subjects undergoing arteriography, were 66.3% and 77.6%, respectively. For measurable disease (mild plus significant), sensitivity was 60.6% and specificity 85.9%. Positive and negative predictive values were 37.7% and 91.9%, respectively, for significant disease. For measurable disease, positive and negative predictive values were 68.9% and 80.9%, respectively. In these asymptomatic young men, a fluoroscopic examination negative for coronary artery calcification indicated a low risk of significant coronary artery disease, whereas a positive test result (calcification present) substantially increased the likelihood of angiographically significant coronary artery disease.

Comparison of serial quantitative evaluation of calcified coronary artery plaque by ultrafast computed tomography in persons with and without obstructive coronary artery disease

Coronary artery calcium indicates atherosclerosis. Ultrafast computed tomography (CT) can noninvasively visualize and quantify coronary calcium, permitting the natural history of calcified plaque to be studied. This pilot study evaluates the ability of ultrafast CT to follow the progression of calcified plaque within the coronary arteries in patients with and without obstructive coronary artery disease (CAD). Twenty-five subjects had serial ultrafast CT scans of the coronary arteries a mean of 406 days apart. Changes in the number of calcific deposits, calcified plaque area and volume, calcium density and total calcium score were measured. In the 20 patients with calcium on the first study, there were statistically significant increases in mean peak CT number, total calcified plaque volume, total calcified plaque area and total calcium score (p less than 0.0001 for all). Subjects with proved obstructive CAD (n = 10) on angiography had a 48% increase in calcified plaque volume compared with 22% in asymptomatic subjects (n = 10). Comparison of serial studies showed that smaller calcific deposits often coalesced into single larger calcific deposits. Ninety-eight percent (235 of 241) of deposits identified on the first study were accounted for on the second study. Patients with obstructive CAD had a higher number of new calcific deposits than did those in the asymptomatic group (55 vs 18, p = 0.058). Serial ultrafast CT accurately tracks the progression of coronary artery calcium. It is a useful technique for assessing changes in calcified plaque formation in both asymptomatic subjects and in patients with obstructive CAD. It may be useful for studying the natural history of CAD and the effects of intervention on the course of CAD.

Coronary artery calcification detected by CT: clinical significance and angiographic correlates

Cardiac computed tomography (CT) to detect coronary calcification was performed on 161 patients undergoing coronary angiography for proven or suspected coronary artery disease. Among 108 patients in whom coronary calcifications was identified, 90% had significant coronary stenosis angiographically (greater than 75% stenosis), and 80% of 121 patients with significant coronary stenosis showed calcification by CT. The relationship between the calcification site and the significance in stenosis of each vessel was determined. Calcification was present in 133 arteries among 205 stenotic coronary arteries (sensitivity = 65%) as compared with 59 of 439 entire arteries with normal coronary angiograms (specificity = 87%). In the younger age group the sensitivity of calcification for stenosis of each coronary artery was lower and the specificity and predictive value were generally higher than those in the elderly group. These results demonstrate that CT is a valuable procedure for detecting coronary arterial disease, since this examination is easy to conduct, noninvasive, and widely applicable for screening a large population.

Cardiac fluoroscopy for the diagnosis of coronary artery disease: a meta analytic review

To evaluate variability in the reported accuracy of fluoroscopically detected coronary calcific deposits for predicting angiographic coronary disease, we applied meta analysis to 13 consecutively published reports comparing the results of cardiac fluoroscopy with coronary angiography. Population characteristics and technical and methodologic factors were analyzed. Sensitivity and specificity for predicting serious coronary disease compare quite well with those from the literature on the exercise ECG and the exercise thallium scintigram. Sensitivity increases and specificity decreases more significantly with patient age, and sensitivity is paradoxically lower in laboratories testing patients with more severe disease, as well as when 70% rather than 50% diameter narrowing is used to define angiographic disease. Work-up and test review bias were also significantly related to reported accuracy.

Calcific deposits in the heart

Four case reports are presented which illustrate various patterns of calcific deposits in the heart. Valvular, myocardial, intracavitary, and coronary calcific deposits are illustrated, with emphasis on pathology and clinicopathologic-radiologic correlation. "Dystrophic" and "metastatic" calcifications are terms used to describe calcific deposits in abnormal and normal soft tissues, respectively. These terms are somewhat confusing in relation to the myocardium, however, as the chronologic sequence of cardiac injury is often uncertain. We suggest that these terms be avoided in relation to the heart, in favor of simple descriptive terms such as "myocardial calcific deposits." Many conditions, such as renal failure and hypercalcemia may contribute to the likelihood of soft tissue calcification, although a definite common etiology has not been identified. Likewise, soft tissue calcification has been difficult to diagnose premortem. The advent of ultrafast (cine) computed tomography may provide a quick, noninvasive, highly sensitive and specific method for diagnosis of soft tissue calcific deposits in the future.

Quantification of coronary artery calcium using ultrafast computed tomography

Ultrafast computed tomography was used to detect and quantify coronary artery calcium levels in 584 subjects (mean age 48 +/- 10 years) with (n = 109) and without (n = 475) clinical coronary artery disease. Fifty patients who underwent fluoroscopy and ultrafast computed tomography were also evaluated. Twenty contiguous 3 mm slices were obtained of the proximal coronary arteries. Total calcium scores were calculated based on the number, areas and peak Hounsfield computed tomographic numbers of the calcific lesions detected. In 88 subjects scored by two readers independently, interobserver agreement was excellent with identical total scores obtained in 70. Ultrafast computed tomography was more sensitive than fluoroscopy, detecting coronary calcium in 90% versus 52% of patients. There were significant differences (p less than 0.0001) in mean total calcium scores for those with versus those without clinical coronary artery disease by decade: 5 versus 132, age 30 to 39 years; 27 versus 291, age 40 to 49 years; 83 versus 462, age 50 to 59 years; and 187 versus 786, age 60 to 69 years. Sensitivity, specificity and predictive values for clinical coronary artery disease were calculated for several total calcium scores in each decade. For age groups 40 to 49 and 50 to 59 years, a total score of 50 resulted in a sensitivity of 71% and 74% and a specificity of 91% and 70%, respectively. For age group 60 to 69 years, a total score of 300 gave a sensitivity of 74% and a specificity of 81%. The negative predictive value of a 0 score was 98%, 94% and 100% for age groups 40 to 49, 50 to 59 and 60 to 69 years, respectively. Ultrafast computed tomography is an excellent tool for detecting and quantifying coronary artery calcium.

Coronary artery calcification identified by CT in patients over forty years of age

In a study of 100 unselected patients forty years of age or older, routine CT of the thorax demonstrated coronary artery calcification in 41%. Calcification of the left anterior descending was most common, occurring in 34%. For patients 60 years of age and over, clinical evidence of coronary artery disease was 1.7 times more common in those with calcification compared to those without; however, for patients under 60, coronary artery disease was 5.5 times more common in those with calcification than those without. Because of the strong relationship that is known to exist between coronary artery calcification and coronary arteriosclerosis, we believe that the incidental discovery of coronary artery calcification on routine CT of the thorax has significance. All patients under 60 with coronary artery calcification discovered on CT should be investigated for hyperlipidemia if this has not been done, and, if they are not known to have a history of coronary artery disease, they should have a stress test and, if positive, arteriography may be warranted.

Association of coronary calcification with obstructive disease in coronary arteries in Indian patients

A total of 1150 consecutive patients (1052 males and 98 females; age 51.2 +/- 10.1 years) with suspected coronary artery disease (Group I) were subjected to fluoroscopy for detection of coronary artery calcification (CAC) and coronary angiography. Another group (Group II) of 120 patients (95 males and 25 females; age 51.4 +/- 9.4 years) catheterized for cardiac diseases other than coronary artery disease (CAD) were subjected to the same protocol of fluoroscopy and coronary angiography to exclude incidental CAD in view of their age. CAC was present in 240 patients (20.0%) in Group I. Of these, 200 (83.4%) had triple-vessel disease (TVD); 20 (8.3%) had double-vessel disease (DVD); 19 (7.9%) had single-vessel disease (SVD); and 37 (15.4%) patients had left main coronary disease (LMCAD). Only one of these patients had insignificant CAD considered as "normal" coronary arteries (NC). Incidence of LMCAD, TVD, DVD, SVD, and NC in patients without CAC was 4.4%, 56.3%, 18.2%, 14.0%, and 11.5%, respectively. Incidence of CAC in patients with LMCAD, TVD, DVD, SVD, and NC was 48.1%, 28.1%, 10.8%, 13.0%, and 1.0% respectively. In Group II (n = 120), 24 patients (20%) had CAD, CAC was present in 5 patients with CAD (20.9%), and in two patients without CAD (2%). CAC is relatively uncommon in Indian CAD patients. Its presence, however, indicates severe multivessel disease.

Value of fluoroscopy in the detection of coronary stenosis: influence of age, sex, and number of vessels calcified on diagnostic efficacy

Although fluoroscopically detected coronary artery calcification is known to correlate with the presence of coronary artery stenosis, age, sex, and extent of calcification influence the strength of this association. To clarify its diagnostic potential, we performed fluoroscopy before coronary angiography in 600 patients and analyzed the results according to all three factors simultaneously. The sensitivity of fluoroscopy for significant stenosis exceeded 65% in all groups except women less than 45 years of age. Specificity exceeded 90% in patients less than 45 years and 85% in patients less than 55 years of age, and declined significantly with age. The number of vessels calcified was an important determinant of predictive value, except in those less than 45 years of age in whom even a single mild calcification markedly increased the chance of stenosis. In patients aged 45 to 64 years, calcification of two or three vessels substantially increased the chances of stenosis, but single-vessel calcification increased the risk only slightly. In patients more than 65 years of age, fluoroscopy was not helpful in detecting stenosis, regardless of the number of vessels calcified. Our findings were similar in men and women. We conclude that if both age and the number of vessels calcified are considered, fluoroscopy can provide useful information regarding the presence of stenosis in young and middle-aged patients.

Cardiac cinefluoroscopy as an inexpensive aid in the diagnosis of coronary artery disease

To compare the accuracy of cinefluoroscopy, exercise electrocardiography and thallium perfusion imaging in diagnosing coronary artery disease (CAD), these 3 studies were performed in 297 subjects without prior acute myocardial infarction who were referred for coronary angiography. Of the 137 patients who had more than 50% angiographic diameter narrowing in at least 1 major coronary artery, 91 (67%) were correctly identified by cinefluoroscopy, 90 (66%) by stress electrocardiography and 100 (73%) by thallium imaging. Of the 164 patients with no more than 50% diameter narrowing, the proportion of patients correctly identified as normal were 81%, 72% and 79%, respectively. Cardiac cinefluoroscopy correctly classified 74% of the 297 subjects as to their disease status (more than 50% coronary narrowing), compared to 69% for stress electrocardiography and 76% for thallium imaging. There was no significant difference between the sensitivity or specificity of the test combination of stress electrocardiography and cinefluoroscopy and the combination of stress electrocardiography and thallium imaging. Cardiac cinefluoroscopy, a relatively cost-effective diagnostic test, is similar in accuracy to other, more expensive noninvasive diagnostic examinations for CAD.

Combined cardiac cinefluoroscopy, exercise testing and ambulatory ST-segment monitoring in the diagnosis of coronary artery disease; a report of 104 symptomatic patients

To enhance diagnostic accuracy in coronary artery disease, cardiac cinefluoroscopy for the detection of coronary artery calcification was combined with exercise test and ambulatory ST-segment monitoring in 104 symptomatic patients before they underwent coronary angiography. In 44 patients with typical angina the combination of the three noninvasive tests and the exercise test alone both detected 92% of subjects with clinically important coronary artery disease. In 60 patients with atypical angina, the combination of the three noninvasive tests screened 77% of the subjects with clinically important coronary artery disease versus 43% after exercise test only (P less than 0.001). The exercise electrocardiogram was false negative in a substantial number of patients with atypical angina due to the presence of a good coronary reserve or to a daily circadian variation in the tone of the coronary arteries. Under these circumstances, cardiac cinefluoroscopy gave additional anatomic information to the physiological assessment of ischemia provided by the exercise test and ambulatory ST-segment monitoring. Our study suggests that the combination of cardiac cinefluoroscopy with other noninvasive tests may be particularly useful in screening atypically symptomatic populations.

Radiographic evaluation of the patient with chest pain of suspected myocardial origin

The evaluation of the patient with suspected angina pectoris is discussed and an approach presented which makes use of radiologic tests in conjunction with exercise testing to quickly and efficiently determine the likelihood and severity of coronary artery disease. The relative merits and limitations of chest radiography, cardiac fluoroscopy, nuclear medicine, and coronary arteriography are discussed.

Computer-assisted diagnosis in the noninvasive evaluation of patients with suspected coronary artery disease

A microcomputer program called CADENZA, which employs Bayes' theorem to analyze and report the results of various clinical descriptors and noninvasive tests relative to the diagnosis of coronary artery disease, was evaluated in 1,097 consecutive patients without previous myocardial infarction. With this program, each patient was characterized by a probability for coronary artery disease, based on Framingham risk factor analysis, symptom characterization, electrocardiographic stress testing, cardiokymography, cardiac fluoroscopy, thallium perfusion scintigraphy and technetium equilibrium-gated blood pool scintigraphy. A total of 11,808 probability estimates derived from various combinations of the available observations were analyzed: 2,180 in 170 patients undergoing coronary angiography and 9,628 in 969 patients who completed a 1 year follow-up for coronary events. The predicted probability of disease correlated linearly with observed angiographic prevalence in the 170 patients who subsequently had coronary angiography (prevalence = [0.001 +/- 0.011] + [0.966 +/- 0.019] X probability). The difference between probability and prevalence averaged 3.1%, and the magnitude of this correlation was not affected by the type or amount of data analyzed. The prevalence of multivessel disease in these patients increased as a monotonic function of disease probability. Below a probability of 25%, single vessel disease was slightly more common than multivessel disease. Above a probability of 75%, multivessel disease predominated. In the 969 patients followed up for 1 year from the date of testing, the incidence of cardiac death and nonfatal infarction increased as a cubic function of disease probability (from approximately 0 to 8% per year for each). Above a probability of 90%, however, the standard deviation for predicting these events was wide. These data indicate that Bayes' theorem in general--and CADENZA in particular--is an accurate, clinically applicable means for quantifying the prevalence of angiographic coronary artery disease, the risk of multivessel disease and the incidence of morbid coronary events in the year after testing.

Computer-enhanced thallium scintigrams in asymptomatic men with abnormal exercise tests

The use of treadmill testing in asymptomatic patients and those with an atypical chest pain syndrome is increasing, yet the proportion of false positive stress electrocardiograms increases as the prevalence of disease decreases. To determine the diagnostic accuracy of computer-enhanced thallium perfusion scintigraphy in this subgroup of patients, multigated thallium scans were obtained after peak exercise and 3 or 4 hours after exercise and the raw images enhanced by a computer before interpretations were made. The patient group consisted of 191 asymptomatic U.S. Air force aircrewmen who had an abnormal exercise electrocardiogram. Of these, 135 had normal coronary angiographic findings, 15 had subcritical coronary stenosis (less than 50 percent diameter narrowing) and 41 had significant coronary artery disease. Use of computer enhancement resulted in only four false positive and two false negative scintigrams. The small subgroup with subcritical coronary disease had equivocal results on thallium scintigraphy, 10 men having abnormal scans and 5 showing no defects. The clinical significance of such subcritical disease in unclear, but it can be detected with thallium scintigraphy. Thallium scintigrams that have been enhanced by readily available computer techniques are an accurate diagnostic tool even in asymptomatic patients with an easily interpretable abnormal maximal stress electrocardiogram. Thallium scans can be effectively used in counseling asymptomatic patients on the likelihood of their having coronary artery disease.

Predictive accuracy of coronary artery calcification and abnormal exercise test for coronary artery disease in asymptomatic men

To determine the predictive accuracy of fluoroscopically detected coronary artery calcification (CAC) and a positive submaximal exercise test, 129 asymptomatic men were screened; 13 had both coronary artery calcification and positive exercise test (greater than or equal to 1.0 mm ST-segment depression). These 13 men were studied at coronary arteriography. They had a mean age of 44 years (range 41-56 years); none had history or symptoms of heat disease and all had normal resting ECGs at entry. CAC was detected in one artery in 10 men, in two arteries in two men, and in three arteries in one man. Coronary artery disease (CAD) was considered clinically significant if any major coronary branch was narrowed > 50%. Coronary arteriography revealed 12 men with clinically significant CAD (one-vessel CAD in four, two-vessel CAD in five and three-vessel CAD in three men) and one man with minor one-vessel CAD. The predictive accuracy was 100% for minor CAD and 92% for clinically significant CAD. The location of CAC and CAD correlated, but the absence of CAC did not rule out the presence of CAD at coronary arteriography. Furthermore, CAC did not indicate the location of the highest stenotic (most occlusive) lesions seen at arteriography. Follow-up for the 13 patients was 36 months; three patients developed typical angina and one patient developed a transmural myocardial infarction. This study suggests that the predictive accuracy of CAC and a positive exercise test in the middle-aged non-hyperlipidemic asymptomatic male is very high (100% for CAD and 92% for clinically significant CAD) and that CAC and a positive exercise test predict an early appearance of angina or myocardial infarction in previously asymptomatic men.

Methodologic problems of exercise testing for coronary artery disease: groups, analysis and bias

To determine why exercise testing remains controversial as a diagnostic test for coronary artery disease, a methodologic review was undertaken of 33 studies comprising 7,501 patients who had undergone both exercise tests and coronary angiography. Of seven methodologic standards for research design, only one received general compliance: the requirement for an adequate variety of anatomic lesions. Less than half of the studies complied with any of the remaining six standards: adequate identification of the groups selected for study; adequate analysis for relevant chest pain syndromes; avoidance of a limited challenge group; and avoidance of work-up bias, diagnostic review bias and test review bias. Only one study met as many as five standards. These methodologic problems may explain the wide range of sensitivity (35 to 88 percent) and specificity (41 to 100 percent) found for exercise testing, because the variations could not be attributed to the usual explanations: definition of anatomic abnormality, stress test technique or definition of an abnormal test. Determining the true value of exercise testing requires methodologic improvements in patient selection, data collection and data analysis.

Application of conditional probability analysis to the clinical diagnosis of coronary artery disease

Analysis of multiple noninvasive tests offers the promise of more accurate diagnosis of coronary artery disease, but discordant test responses can occur frequently and, when observed, result in diagnostic uncertainty. Accordingly, 43 patients undergoing diagnostic coronary angiography were evaluated by noninvasive testing and the results subjected to analysis using Bayes' theorem of conditional probability. The procedures used included electrocardiographic stress testing for detection of exercise-induced ST segment depression, cardiokymographic stress testing for detection of exercise-induced precordial dyskinesis, myocardial perfusion scintigraphy for detection of exercise-induced relative regional hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification. The probability for coronary artery disease was estimated by Bayes' theorem from each patient's age, sex, and symptom classification, and from the observed test responses. This analysis revealed a significant linear correlation between the predicted probability for coronary artery disease and the observed prevalence of angiographic disease over the entire range of probability from 0 to 100% (P less than 0.001 by linear regression). The 12 patients without angiographic disease had a mean posttest likelihood of only 7.0 +/- 2.6% despite the fact that 13 of the 60 historical and test responses were falsely "positive." In contrast, the mean posttest likelihood was 94.1 +/- 2.8% in the 31 patients with angiographic coronary artery disease, although 45 of the 155 historical and test responses were falsely "negative." In 8 of the 12 normal patients, the final posttest likelihood was under 10% and in 26 of the 31 coronary artery disease patients, it was over 90%. These estimates also correlated well with the pooled clinical judgment of five experienced cardiologists (P less than 0.001 by linear regression). The observed change in probability for disease for each of the 15 different test combinations correlated with their information content predicted according to Shannon's theorem (P less than 0.001 by linear regression). These results support the use of probability analysis in the clinical diagnosis of coronary artery disease and provide a formal basis for comparing the relative diagnostic effectiveness and cost-effectiveness of different test combinations.