Vasodilator stress impairs the left ventricular function obtained with gated single-photon emission computed tomography in patients with known or suspected coronary artery disease.

BACKGROUND: Transient ischemic dilatation (TID) and post-stress dysfunction of the left ventricle (LV) are important markers of severe coronary artery disease (CAD). To clarify the effects of stressor type on TID and post-stress LV dysfunction, changes in LV measurements were compared between patients with exercise- or vasodilator-induced stress. METHODS AND RESULTS: The 689 patients referred for technetium-99m tetrofosmin myocardial perfusion imaging were included. Patients were stressed with either a vasodilator (n=236) or exercise (n=453). LV measurements were obtained with ECG-gated SPECT. LV end-diastolic and end-systolic volume indexes (LVEDVI, LVESVI) increased and LV ejection fraction (LVEF) decreased after stress in the vasodilator-stress group. Vasodilator-stress and the summed difference score (SDS) were independent variables that decreased LVEF after stress. Even in patients without reversible defects, vasodilator-stress impaired LV function. There were no differences in the stress-to-rest ratios of LVEDVI (rEDV) and LVESVI (rESV) among patients with normal myocardial perfusion, fixed defects and reversible defects in the vasodilator-stress group, whereas in the exercise-stress group, rESV was significantly higher in the patients with reversible defects than in those without reversible defects. Within the vasodilator-stress group, neither rEDV nor rESV correlated with the SDS. CONCLUSIONS: Vasodilator-stress by itself decreases LVEF after stress. TID should be carefully interpreted when vasodilator-stress is used to detect severe CAD.

Evaluation of right and left ventricular function by quantitative blood-pool SPECT (QBS): comparison with conventional methods and quantitative gated SPECT (QGS).

Though quantitative ECG-gated blood-pool SPECT (QBS) has become a popular tool in research settings, more verification is necessary for its utilization in clinical medicine. To evaluate the reliability of the measurements of left and right ventricular functions with QBS, we performed QBS, as well as first-pass pool (FPP) and ECG-gated blood-pool (GBP) studies on planar images in 41 patients and 8 healthy volunteers. Quantitative ECG-gated myocardial perfusion SPECT (QGS) was also performed in 30 of 49 subjects. First, we assessed the reproducibility of the measurements of left and right ventricular ejection fraction (LVEF, RVEF) and left and right ventricular end-diastolic volume (LVEDV, RVEDV) with QBS. Second, LVEF and RVEF obtained from QBS were compared with those from FPP and GBP, respectively. Third, LVEF and LVEDV obtained from QBS were compared with those from QGS, respectively. The intra- and inter-observer reproducibilities were excellent for LVEF, LVEDV, RVEF and RVEDV measured with QBS (r = 0.88 to 0.96, p < 0.01), while the biases in the measurements of RVEF and RVEDV were relatively large. LVEF obtained from QBS correlated significantly with those from FPP and GBP, while RVEF from QBS did not. LVEF and LVEDV obtained from QBS were significantly correlated with those from QGS, but the regression lines were not close to the lines of identity. In conclusion, the measurements of LVEF and LVEDV with QBS have good reproducibility and are useful clinically, while those of RVEF and RVEDV are less useful compared with LVEF and LVEDV. The algorithm of QBS for the measurements of RVEF and RVEDV remains to be improved.

Improvement of cardiac sympathetic innervation by renal transplantation.

UNLABELLED: Chronic renal failure (CRF) patients on dialysis frequently show reduced heart rate variability (HRV), which has been reported to be corrected by renal transplantation. Recently, (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy has been used to evaluate cardiac sympathetic innervation, and uremic patients often show marked abnormalities of cardiac (123)I-MIBG uptake. We investigated whether renal transplantation can improve cardiac (123)I-MIBG uptake in patients with CRF on dialysis. METHODS: We analyzed time- and frequency-domain measures of 24-h HRV and cardiac (123)I-MIBG scintigraphy before and 1-3 mo after renal transplantation in 13 CRF patients on dialysis and in 10 control subjects. RESULTS: Both 24-h HRV and cardiac (123)I-MIBG uptake were significantly abnormal in the patients before transplantation compared with the control subjects. After transplantation, (123)I-MIBG washout rate from the myocardium significantly decreased from 46% +/- 21% to 20% +/- 22% (P = 0.006), and the heart-to-mediastinum ratio of (123)I-MIBG uptake in the late image significantly increased from 1.74 +/- 0.39 to 2.06 +/- 0.39 (P = 0.006). On the other hand, HRV measures tended to increase after transplantation but the changes did not reach statistical significance (P > 0.05). CONCLUSION: Renal transplantation provides the improvement of uremic cardiac sympathetic neuropathy assessed by (123)I-MIBG imaging, which may be a more sensitive or at least an earlier marker than HRV.

Longitudinal study on white blood cell count and the incidence of metabolic syndrome.

OBJECTIVE: Many studies have revealed that white blood cell count (WBC) is related to insulin resistance which is a central mechanism of metabolic syndrome (MetS). However, few cohort studies have examined the role of WBC in the development of MetS. We hypothesized that WBC is associated with the future development of MetS, and investigated the longitudinal incidence of MetS in healthy workers. METHODS: WBC was measured in 5,073 workers (mean age 42.5 years) without MetS at baseline. The incidence of MetS was monitored over 7 years of follow-up, in relation to quartiles of WBC. During the follow-up, 925 participants were diagnosed as MetS. RESULTS: Incidence of MetS was increased in participants with higher WBC: the rates of incidence of MetS were 22.6, 32.9, 42.9, and 57.5 per 1,000 person-years of follow-up in the 1st, 2nd, 3rd, and 4th quartiles of WBC, respectively. After adjustments for confounding factors, the adjusted hazards ratio (95% confidence interval) for MetS was 1.00 (reference), 1.22 (0.98 to 1.51), 1.52 (1.24 to 1.87), and 1.66 (1.35 to 2.04) through the quartiles of WBC, respectively, (p <0.001). This relationship was consistent among current smokers and never smokers, and among male and female genders, respectively. CONCLUSION: WBC is useful in predicting the future development of MetS which leads to atherosclerotic diseases.

Medical check-up findings characteristic of smokers: aimed at improving smoking cessation interventions by physicians.

OBJECTIVE: The purpose of this study was to elucidate the medical check-up findings associated with smoking habit, which medical professionals, particularly physicians, should use for the promotion of quitting smoking. METHODS: In 6,215 male and 1,627 female employees who participated in annual medical check-up, we compared the results of each test between smokers and nonsmokers. RESULTS: Many results were significantly different between smokers and nonsmokers in both males and females. Among them, the hematocrit, leukocyte count, and levels of hemoglobin and triglyceride were significantly higher, the level of high-density lipoprotein cholesterol was significantly lower, and the frequencies of positive urinary occult blood and hearing loss were significantly higher in male smokers than in male nonsmokers. Furthermore, the hematocrit, leukocyte count, positive urinary occult blood, hearing loss, and levels of hemoglobin, triglyceride, and high-density lipoprotein cholesterol showed significant trends for male nonsmoker, and light, moderate, and heavy male smokers, that is, significant associations with larger numbers of cigarettes smoked per day. CONCLUSION: Not only polycythemia and low high-density lipoprotein cholesterol level but also high leukocyte count, hearing loss, positive urinary occult blood, and high triglyceride level are smoking-related abnormal findings. In the medical check-up, medical professionals should inform smokers of these data and encourage them to quit smoking.

[Usefulness of lung and right ventricular thallium-201 uptake during single photon emission computed tomography in exercise testing of patients with coronary artery disease].

OBJECTIVES: Increased pulmonary or right ventricular 201Tl uptake during the exercise test has been used as a marker of multivessel coronary artery disease. The most useful method for assessing the severity of coronary artery disease was evaluated among conventional evaluation of single photon emission computed tomography (SPECT), measurement of lung to heart uptake ratio (L/H), and right ventricular to left ventricular uptake ratio (RV/LV) on 201Tl images during exercise testing. METHODS: Regions-of-interest (4 X 4 pixels) were placed at the lung and the heart, and L/H was defined as mean lung uptake/mean heart uptake. Correspondingly, regions-of-interest (4 X 4 pixels) were placed at the RV and the LV, and RV/LV was defined as maximum RV uptake /maximum LV uptake. L/H and RV/LV on the initial image were analyzed in 216 patients(angiographically normal coronary arteries: 89, single-vessel disease: 82, multivessel disease: 45). The diagnostic value was evaluated using the receiver operating characteristic curve. RESULTS: All methods showed significantly higher values in patients with multivessel disease than in patients with no coronary artery disease or single-vessel disease. L/H was significantly higher in patients with prior myocardial infarction and RV/LV was significantly higher in patients without infarction. The sensitivity of only conventional SPECT evaluation for multivessel coronary artery disease was low (sensitivity 53%, specificity 94%). However, addition of evaluation of L/H and RV/LV to SPECT improved the sensitivity for multivessel coronary artery disease (sensitivity 93%, specificity 49%). CONCLUSIONS: The diagnostic sensitivity for multivessel coronary artery disease was improved by adding L/H and RV/LV to conventional evaluation of exercise 201Tl SPECT. L/H and RV/LV during exercise 201Tl imaging may provide additional information regarding the severity of coronary artery disease.

Usefulness of stress myocardial perfusion imaging for evaluating asymptomatic patients after coronary stent implantation.

BACKGROUND: Stent implantation in coronary angioplasty has reduced the rate of restenosis, but many patients still undergo follow-up coronary angiography (CAG). The present study was a multi-center retrospective analysis of the usefulness of stress single photon emission computed tomography (SPECT) compared with follow-up CAG in stent-implanted patients who remained asymptomatic during the follow-up period. METHODS AND RESULTS: The study group of 103 patients underwent both SPECT and CAG at 4-9 months after stent implantation. Restenosis occurred in 20 (19%) of 106 vessel territories, and a reversible perfusion defect was found in 32 (30%) territories. Sensitivity, specificity, positive and negative predictive values, and accuracy of SPECT were 65%, 78%, 41%, 91%, and 76%, respectively. The accuracy was lower in territories with a prior myocardial infarction (71%), in the left circumflex artery (58%), and in cases with three-vessel disease (63%). The negative predictive value was high, but 7 false negative cases included 4 cases with prior myocardial infarction, and 2 cases with reversible defects in other vessel territories. CONCLUSIONS: Stress SPECT imaging is a useful tool for following up patients with coronary stent implantation, and follow-up CAG could be omitted in patients with negative SPECT imaging, no prior myocardial infarction, one- or two-vessel disease, and sufficient stress loading.