Effect of Low-Frame Invasive Coronary Angiography on Radiation and Image Quality.

Invasive coronary angiography (ICA) uses harmful x-ray energy. To date, there are no studies evaluating the effect of performing ICA at lower than the standard 15 frames per second (f/s) on radiation dose and image quality. In this study, we investigated the effect of performing ICAs at 7.5 f/s as opposed to the standard 15 f/s on radiation exposure and image quality. Thirty-nine patients referred for ICA for clinical indications were assigned to have their ICA performed at 7.5 f/s or 15 f/s in a 2:1 ratio, respectively. All studies were performed by one experienced operator in the same laboratory. Magnification, table height, collimation, number of images, and specific angles for image acquisition were kept constant to account for these variables that also effect radiation. Studies performed at 7.5 f/s had significantly less radiation exposure than those performed at 15 f/s (252.2 mGy vs 433.7 mGy, p <0.01). In addition, radiation per unit time was also significantly reduced in the 7.5 f/s versus the 15 f/s group (140.0 mGy/min vs 254.7 mGy/min, p <0.01). Image quality was evaluated by an experienced operator blinded to the goals of the study; allstudies were graded as good to excellent. In conclusion, performing ICA at 7.5 f/s versus 15 f/s significantly reduces x-ray exposure without compromising image quality. The results of this single-center study warrant a larger randomized clinical trial.

Low lifetime recreational activity is a risk factor for peripheral arterial disease.

BACKGROUND: The relationship between lifetime physical activity and the risk of developing peripheral arterial disease (PAD) is not known. METHODS: We studied 1381 patients referred for elective coronary angiography in a point prevalence analysis. PAD was defined as ankle-brachial index (ABI) <0.9 at the time or a history of revascularization of the lower extremities regardless of ABI measure. We used a validated physical activity questionnaire to retrospectively measure each patient's lifetime recreational activity (LRA). Multivariate and logistic regression analyses were used to assess the independent association of LRA to ABI and the presence of PAD. RESULTS: PAD was present in 19% (n = 258) of all subjects. Subjects reporting no regular LRA had greater diastolic blood pressure and were more likely to be female. They had lower average ABI, and a higher proportion had PAD (25.6%). In a regression model, including traditional risk factors and LRA, multivariate analysis showed that age (P < .001), female gender (P < .001), systolic blood pressure (P = .014), fasting glucose (P < .001), serum triglycerides (P = .02), and cumulative pack years (P < .001) were independent negative predictors of ABI, and LRA was a positive predictor of ABI (P < .001). History of sedentary lifestyle independently increased the odds ratio for PAD (odds ratio, 0.46; 95% confidence interval, 1.01-2.10) when assessed by logistic regression. Intriguingly, there is a correlation between physical activity and gender, such that women with low LRA are at greatest risk. CONCLUSION: Recalled LRA is positively correlated to ABI and associated with PAD. Whereas the mechanism for this effect is not clear, LRA may be a useful clinical screening tool for PAD risk, and strategies to increase adult recreational activity may reduce the burden of PAD later in life.

Sex differences in the prevalence of peripheral artery disease in patients undergoing coronary catheterization.

To determine whether there are sex differences in the prevalence of peripheral artery disease, we performed an observational study of 1014 men and 547 women, aged ≥ 40 years, referred for elective coronary angiography. Women were slightly older, more obese, had higher low-density lipoprotein cholesterol (LDL-C) levels and systolic blood pressure (BP), and were more likely to be African American. Women had higher high-density lipoprotein cholesterol (HDL-C) levels, lower diastolic BP, and were less likely to smoke or to have a history of cardiovascular disease. Women had less prevalent (62% vs 81%) and less severe coronary artery disease (CAD) (p < 0.001 for both) by coronary angiography, but more prevalent peripheral artery disease (PAD) as determined by the ankle-brachial index (ABI) than men (23.6% versus 17.2%). Independent predictors of lower ABI were female sex, black race, older age, tobacco use, CAD, diabetes, and triglyceride level. In a full multivariable logistic regression model, women had a risk-adjusted odds ratio for PAD of 1.78 (95% CI 1.25-2.54) relative to men. Among patients referred for coronary angiography, women have less prevalent and less severe CAD, but more prevalent PAD, a sex difference that is not explained by traditional cardiovascular disease risk factors or CAD severity. Clinical Trial Registration-URL: http://clinicaltrials.gov. Unique identifier: NCT00380185.

Age and double product (systolic blood pressure x heart rate) reserve-adjusted modification of the Duke Treadmill Score nomogram in men.

The Duke Treadmill Score (DTS) is an established clinical tool for risk stratification. Our aim was to determine if other variables could improve the prognostic power of the DTS and if so, to modify the DTS nomogram. From a total of 1,959 patients referred for exercise testing at the Palo Alto VA Medical Center from 1997 to 2006 (a mean follow-up of 5.4 years), we studied 1,759 male veterans (age 57 +/- 12 years) free of heart failure. Double product (DP) was calculated by multiplying systolic blood pressure and heart rate; variables and their products were subtracted to obtain the differences between at rest and maximal exercise (reserve) and recovery. Of all the hemodynamic measurements, DP reserve was the strongest predictor of cardiovascular death (CVD) (Wald Z-score -3.84, p <0.001) after adjustment for potential confounders. When the components of DTS were entered in the Cox hazard model with DP reserve and age, only DP reserve and age were chosen (p <0.00001). Using the Cox coefficients, a score calculated by [age - DTS - 3 x (DP reserve/1,000)] yielded an area under the curve of 0.84 compared with 0.76 for the DTS. Using this equation, a nomogram was constructed by adding age and DP reserve to the original DTS nomogram improving estimation of annual CVD. In conclusion, we propose an age and DP reserve-adjusted DTS nomogram that improves the prognostic estimates of average annual CVD over the DTS alone.

Prognostic value of double product reserve.

BACKGROUND: Although the prognostic power of exercise capacity has been demonstrated, the relative prognostic potential of other hemodynamic responses has not been thoroughly investigated. We aimed to assess the prognostic power of double product (DP) parameters in patients referred for standard exercise testing. DESIGN: A retrospective cohort study. METHODS: Analyses were performed on 1959 patients referred for exercise testing at the Palo Alto Veterans Affairs Medical Center from 1997 to 2006. After removal of female and heart failure patients, 1759 male veterans (mean age 57+/-12 years) remained. DP was calculated by multiplying systolic blood pressure (SBP) and heart rate (HR); variables and their products were subtracted to obtain the differences between rest and maximal exercise (reserve), and recovery. RESULTS: Multivariable Cox survival analysis was performed for 157 all-cause and 53 cardiovascular deaths during a mean follow-up of 5.4+/-2.1 years. Although most of the hemodynamic variables were individually significant in Cox survival analysis, when age, DP reserve, exercise capacity (in metabolic equivalents), and HR recovery were entered together, only age and DP reserve were chosen. Of all hemodynamic measurements considered, DP reserve was the strongest predictor of cardiovascular prognosis after adjustment for age (Wald Z-score,-5.12; P<0.0001) and when considering other potential confounders such as age, beta-blocker use, and the Duke treadmill Score (Wald Z-score,-3.84; P<0.0001). CONCLUSION: In this study population, DP reserve had greater prognostic power than metabolic equivalents, maximal HR or systolic blood pressure, or HR recovery.

In vivo imaging and evaluation of different biomatrices for improvement of stem cell survival.

Therapeutic effects from injection of stem cells are often hampered by acute donor cell death as well as migration away from damaged areas. This is likely due to the fact that injected cells do not have the physical and biochemical cues for ordered engrafment. Here we evaluate 3 common biomatrices (Matrigel, Collagen I, Purmatrix) that has the potential of providing suitable scaffolds needed to enhance stem cell survival. The longitudinal fate of transplanted stem cells was monitored by reporter imaging techniques.