Quantitative characterization of myocardial properties represent a rapidly emerging area of echocardiographic investigation. Because measurement of the ultrasonic integrated backscatter is theoretically applicable to analysis in vivo with reflected ultrasound, this study was performed to develop and evaluate a suitable method for measurement of quantitative backscatter in vivo. In view of the desirability of characterizing ischemic myocardium noninvasively, the study was performed with animal preparations simulating myocardial ischemia in humans. In one series of open-chest dogs, integrated backscatter among 22 ischemic regions was increased by 200% (P less than 0.01) compared to values in control regions within 1 hour after coronary occlusion and by 400% (-45.1 +/- 0.7 dB compared to -50.9 +/- 0.4 dB) (P less than 0.001) within 6 hours. In a second series of open-chest dogs, ischemia was quantified with 141Ce microspheres, and mean integrated backscatter was found to increase (280% of control) (P less than 0.01) in regions with flow less than 20% of control 2 hours following coronary occlusion. Additional studies with perfused hearts revealed two determinants of the increased ultrasonic backscatter observed: (1) an increase in cardiac fluid content reflected by the wet-to-dry weight ratio, and (2) the contributions of formed elements in whole blood. The results indicate that ultrasonic integrated backscatter distinguishes severely ischemic from nonischemic myocardium in vivo in open-chest animals. Because it was possible to obtain these results in the reflection mode, potential extension of the approach to clinical applications is promising.

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The study was conducted as an external analysis of prospectively collected data from Stepathlon, an annual international mHealth based global event conducted in the years 2012-14. Participants were organised in worksite-based teams, issued pedometers, and encouraged to increase daily steps and physical activity via utilisation of a multi-platform app, functional on mobile devices and the internet. The main outcome measures were change in step count, exercise days, sitting duration and weight.Results: The study included n=62905 participants in LMICs, with complete follow-up data available from 32956 participants. Following Stepathlon completion, improvements were seen in step count (+3563 steps/day 95%CI: 3527-3600, P<0.0001), sitting duration (-0.73 hrs/day 95%CI:-0.75,-0.70,P<0.0001), exercise days/week (+0.91, 95%CI: 0.89,0.93,P<0.0001), and weight (-1.51kg, 95%CI: -1.59 to -1.43, P<0.0001). Improvements were seen in women, men, and each year cohort (all P<0.0001).Conclusion: Large scale Mobile Health lifestyle intervention in lower-middle income countries translates to a significant reduction in the cardiovascular risk factors of elevated body weight and physical inactivity.

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