AHA/ASA volunteer expert Larry B. Goldstein, M.D. offers perspective (via Skype) on ISC 19 abstract 9.  He is the Ruth L. Works Professor, the Chairman of the Department of Neurology and Co-Director of the Kentucky Neuroscience Institute in Lexington, KY.
copyright American Heart Association 

"It's obviously quite concerning. Of the investigators found that, of the users of e-cigarettes, or recent users of e-cigarettes, that there's about a 70% increase in the risk of stroke, about a 60% increase in the risk of myocardial infarction, and about a 40% increased risk in coronary heart disease. So, those relevant increase risks are quite significant and quite important on a population level. What isn't in the data, is what the absolute increased risk is, so, it's hard to know how many exposures lead to an increase to that. Another issue is in studies of this type, it's a common problem with all of them, is that the adjustment for potential confounders is limited. They adjust it for age, sex, smoking status, diabetes and body mass index, but there are obviously other factors that can increase the risk of cardio-vascular disease, that weren't measured. One additional concern, is that, of the e-cigarette users, there was an almost doubling in the risk of cigarette smoking. In overall, in 2016, they reported that about 11% or so, of high school students reported using e-cigarettes. So, this is a potential chip of the spear, of a wave of cardio-vascular disease, that may be coming in the future, especially since this has been so attractive to young users."