New concepts in the clinical aspects of cardiovascular disease.

Many patients with HIV infection, as well as those without this disease, may have coronary heart disease (CHD) or be at high risk for this condition. The high prevalence of and risk of CHD among patients with HIV infection are generally caused by traditional risk factors that can be readily managed with currently available therapies. New tools are also available for functional imaging and establishing diagnoses and prognoses in patients who do experience coronary events. Management of these persons requires careful attention to patient characteristics that may influence therapeutic outcomes.

Decreased myocardial perfusion SPECT lung-to-heart ratio: Lucent lungs.

We present a case of a patient with chronic obstructive pulmonary disease whose myocardial perfusion SPECT imaging demonstrated diffusely decreased Tc-99m sestamibi lung uptake ("lucent lungs"); our results indicate that there may be a lower limit of normal for lung-to-heart ratio, below which pathology can be inferred.

Iodofiltic acid I 123 (BMIPP) fatty acid imaging improves initial diagnosis in emergency department patients with suspected acute coronary syndromes: a multicenter trial.

OBJECTIVES: The aim of this study was to assess the performance of beta-methyl-p-[123I]-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) to detect acute coronary syndromes (ACS) in emergency department patients with chest pain. BACKGROUND: Emergency department diagnosis of chest pain is problematic, often requiring prolonged observation and stress testing. BMIPP SPECT detects abnormalities in fatty acid metabolism resulting from myocardial ischemia, even many hours after symptom cessation. METHODS: Emergency department patients with suspected ACS were enrolled at 50 centers. Patients received 5 mCi BMIPP within 30 h of symptom cessation. BMIPP SPECT images were interpreted semiquantitatively by 3 blinded readers. Initial clinical diagnosis was based on symptoms, initial electrocardiograms, and troponin, whereas the final diagnosis was based on all available data (including angiography and stress SPECT) but not BMIPP SPECT. Final diagnoses were adjudicated by a blinded committee as ACS, intermediate likelihood of ACS, or negative for ACS. RESULTS: A total of 507 patients were studied and efficacy was evaluated in 448 patients with sufficient data. The sensitivity of BMIPP by 3 blinded readers for a final diagnosis of ACS and intermediate likelihood of ACS was 71% (95% confidence interval [CI]: 64% to 79%), 74% (95% CI: 68% to 81%), and 69% (95% CI: 62% to 77%); the corresponding specificity of BMIPP was 67% (95% CI: 61% to 73%), 54% (95% CI: 48% to 60%), and 70% (95% CI: 64% to 76%). Compared with the initial diagnosis alone, BMIPP+initial diagnosis increased sensitivity from 43% to 81% (p<0.001), negative predictive value from 62% to 83% (p<0.001), and positive predictive value from 41% to 58% (p<0.001), whereas specificity was unchanged (61% to 62%, p=NS). CONCLUSIONS: The addition of BMIPP data to the initially available clinical information adds incremental value toward the early diagnosis of an ACS, potentially allowing determination of the presence or absence of ACS to be made earlier in the evaluation process. (Safety and Efficacy Iodofiltic Acid I 123 in the Treatment of Acute Coronary Syndrome [Zeus-ACS]; NCT00514501).

Spontaneous transition of an autonomously functioning thyroid adenoma to Graves' disease.

We report a case of a 57-year-old postmenopausal woman with an autonomously functioning thyroid adenoma spontaneously developing Graves' disease (GD) as documented by I-123 scintigraphy. To date, anecdotal case reports citing the progression of an autonomous nodule to GD have documented either a major thyroidal insult, spontaneous or therapeutic, or the activation of thyroid tissue by circulating thyroid stimulating IgG, with variable progression characteristics. In contradiction to the proposed inciting factors, our patient underwent a minimally invasive fine needle aspiration biopsy followed by suppressive pharmacotherapy. Her antithyroid antibody assay detected low titers of thyroperoxidase antibody (<10 U/mL). We conclude that this is a rare case of autonomously functioning adenoma where neither significant thyroid tissue damage nor the presence of thyroid stimulating IgG can be implicated as an inciting trigger in its progression to GD.

Clinical validation of SPECT attenuation correction using x-ray computed tomography-derived attenuation maps: multicenter clinical trial with angiographic correlation.

BACKGROUND: Nonuniform attenuation artifacts cause suboptimal specificity of stress single photon emission computed tomography (SPECT) myocardial perfusion images. In phantoms, normal subjects, and patients suspected of having coronary artery disease (CAD), we evaluated a new hybrid attenuation correction (AC) system that combines x-ray computed tomography (CT) with conventional stress SPECT imaging. METHODS AND RESULTS: The effect of CT-based AC was evaluated in phantoms by assessing homogeneity of normal cardiac inserts. AC improved homogeneity of normal cardiac phantoms from 11% +/- 2% to 5% +/- 1% (P < .001). Attenuation-corrected normal patient files were created from 37 normal subjects with a low likelihood (<3%) of CAD. The diagnostic performance of AC for detection of CAD was evaluated in 118 patients who had stress technetium 99m sestamibi or tetrofosmin stress SPECT imaging and coronary angiography. SPECT images with and without AC were interpreted by 4 blinded readers with different interpretative attitudes. Overall, AC improved the diagnostic performance of all readers, particularly the normalcy rate. The degree of improvement depended on interpretative attitude. Readers prone to high sensitivity or with less experience had the greatest gain in the normalcy rate, whereas a reader prone to higher specificity had improvements in sensitivity and specificity but not the normalcy rate. Importantly, improvement of one diagnostic variable was not associated with worsening of other variables. CONCLUSION: CT-based AC of SPECT images consistently improved overall diagnostic performance of readers with different interpretive attitudes and experience. CT-based AC is well suited for routine use in clinical practice.

QT dispersion and viable myocardium in patients with prior myocardial infarction and severe left ventricular dysfunction.

BACKGROUND: QT dispersion (QTd) has been found to correlate to the amount of viable myocardium in patients with Q-wave myocardial infarction and well-preserved LV function. However, this relationship is unknown in patients with severe left ventricular dysfunction. METHODS: Thirty-four patients with prior large myocardial infarction and severe left ventricular dysfunction underwent Tc-99m sestamibi single photon emission cardiac tomography (SPECT) and F-18 fluorodeoxyglucose (FDG) SPECT. Viability was defined as a defect relative count density (DCD) of at least 20% greater on FDG SPECT. QTd, corrected QT dispersion (QTcd), and QT coefficient of variation (cv) in patients with viable myocardium was compared to those without viable myocardium in the infarct area. RESULTS: Thirteen patients were excluded from analysis for poor FDG images or inadequate ECG tracings. Of the remaining patients, 10 (48%) were found to have viability on FDG SPECT. QTd, QTcd, and QTcv in patients with viability were: 58 +/- 22 ms, 61 +/- 23 ms, and 4.81 +/- 1.76%, respectively, which did not differ significantly from those in patients without viability (QTd = 56 +/- 14 ms, QTcd = 70 +/- 16 ms and Qtcv = 5.06 +/- 1.20% [P = NS]). Moreover, neither FDG defect size, nor LVEF correlated with QTd. CONCLUSIONS: This study indicates no relationship between QTd and viability in patients with myocardial infarction and severe left ventricular dysfunction.