Kamran Akram

Influence of symptomatic status on the prevalence of obstructive coronary artery disease in patients with zero calcium score

BACKGROUND CAC has been used to predict obstructive CAD on invasive coronary angiography. However, it is unknown how the prevalence of obstructive CAD in patients with zero CAC is influenced by the presence or absence of chest pain. METHODS 210 consecutive patients referred for CAC and CorCTA were included in this analysis. Chest pain was defined based on the Diamond-Forrester classification. RESULTS 134 patients (64%) were symptomatic and 76 (36%) were asymptomatic. Seventy patients had negative (33%); 140 had positive CAC (67%). In the symptomatic group with zero CAC, 8.2% (4/49) had an obstructive, non-calcified plaque; of these, 3 were <45 years. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CAC in the symptomatic population for detection of obstructive CAD were 0.86 (0.66-0.95), 0.42 (0.33-0.52), 0.28 (0.19-0.39) and 0.92 (0.8-0.97), respectively (p=0.007). No asymptomatic subject with zero CAC had obstructive CAD. Sensitivity, specificity, PPV and NPV of CAC in the asymptomatic population for detection of obstructive CAD were 1.00 (0.66-1.00), 0.32 (0.21-0.45), 0.18 (0.10-0.31) and 1.00 (0.80-1.00), respectively (p=0.05). Optimal cut-points to predict obstructive CAD and AUC were significantly different in symptomatic versus asymptomatic subjects (91 and 0.78 vs. 296 and 0.89, respectively) (p=0.005). CAC performed much better in symptomatic patients >45 years compared to younger patients to exclude obstructive CAD (AUC: 0.83 vs. 0.5, p<0.001; NPV=0.98). CONCLUSIONS CAC is better in asymptomatic compared to symptomatic subjects, especially in patients

Role of single photon emission computed tomography/computed tomography in localization of ectopic parathyroid adenoma: a pictorial case series and review of the current literature.

The parathyroid glands are located posterior to the upper and lower poles of the thyroid and are derived from the third and fourth pharyngeal pouches. Usually there are only 2 superior glands, whereas only 40% of patients have their inferior glands located near the inferior thyroid poles. Ectopic locations include the carotid sheath, anterior mediastinum, retropharynx, or intrathyroidal locations. Single photon emission computed tomography/computed tomography (SPECT/CT) offers the advantage of combining function and anatomy for exact localization of ectopic parathyroid adenomas. In this pictorial review, we present 4 cases of hyperparathyroidism caused by ectopic parathyroid adenomas and review the literature on the additional value of their localization with SPECT/CT. Combined SPECT/CT scanners permit more reliable localization of ectopic adenomas. The additional information can aid in exact preoperative localization. In one study of 16 patients, SPECT/CT identified 39% more lesions compared with SPECT imaging alone. In other comparisons of planar, SPECT and SPECT/CT imaging modalities, SPECT/CT permitted the highest reader confidence in localization, especially for mediastinal adenomas. Larger studies are needed to establish the role and cost-effectiveness of SPECT/CT.

Abnormal Lipoprotein(a) Levels Predict Coronary Artery Calcification in Southeast Asians but Not in Caucasians: Use of Noninvasive Imaging for Evaluation of an Emerging Risk Factor

Subclinical atherosclerosis can be quantified by coronary artery calcium (CAC) scoring. Due to its high specificity for atherosclerosis, CAC is an excellent phenotypic tool for the evaluation of emerging risk markers. Lipoprotein(a) [Lp(a)] is atherogenic due to the presence of apoB and may be thrombogenic through its apo(a) component. Lp(a) has been linked to cardiovascular events in Caucasians; however, its link to atherosclerosis in various ethnicities remains unclear. We evaluated the ability of Lp(a) mass to predict subclinical atherosclerosis in Southeast Asians and Caucasians, as measured by CAC. Traditional lipid measurements, Lp(a) measurements, and CAC by 64-slice multidetector computed tomography was performed in 103 consecutive patients in the USA and in 104 consecutive patients in Jakarta, Indonesia. Proportion of positive CAC and median CAC in Southeast Asians and in Caucasians was 61.5% and 63.1%, and 23.5 (interquartile range, 0–270) and 13 (interquartile range, 0–388), respectively. Significantly higher proportion of Southeast Asians had elevated Lp(a) levels, compared to Caucasians (51.0% vs. 29.2%; p = 0.005). In Southeast Asians, Lp(a) remained an independent predictor of CAC with an odds ratio of 4.97 (95% confidence interval, 1.56–15.88; p < 0.0001), but not in Caucasians. Receiver operating characteristic analysis showed an improvement in area under the curve from 0.81 to 0.86 (p = 0.05) when including Lp(a) in the predictive model in Southeast Asians. This translated to 7% of Southeast Asians reclassified to correct CAC status. Lp(a) measurements may have a role in risk stratification of Southeast Asians. Ethnic variation should be taken into account when considering the use of Lp(a) measurements in risk assessment.

Influence of symptoms and age on the predictive value of coronary artery calcium scanning.

The study by Henneman et al. ([1][1]) included 40 consecutive patients with suspected acute coronary syndrome who underwent coronary artery calcium (CAC) scoring and computed tomography coronary angiography. Of the entire cohort of 40 patients, 5 had obstructive disease and no presence of CAC. The