There are some evidences that estrogen may protect from stroke or heart attack, though some studies have contrary results too. So a very conclusive evidence of protective effect of the estrogen is not there and it seems that there are many other risk factors too which play heavily compared to estrogen alone. Please see the abstract of this very extensive study;
Stroke is one of the leading causes of death and disability annually, and one of the larger populations for which neuroscience nurses care. Differences in gender have been identified as a risk factor for stroke repeatedly throughout the literature. The purpose of this evidence-based literature review is to provide information to healthcare professionals regarding stroke and its relationship with estrogen, the major female sex hormone. Background information on the three types of stroke is outlined, and information on estrogen compounds and hormone replacement therapy is detailed. A review of articles relating estrogen and/or hormone replacement therapy with stroke was performed. Fifty-seven articles met the criteria for inclusion in the review, 19 articles support the use of estrogen and/or an estrogen-related compound in the prevention or treatment of stroke, 6 articles claim estrogen and/or estrogen-related compounds are risk factors for stroke, and 11 articles remain inconclusive with regard to an estrogen and stroke relationship.
Estrogen and stroke: a review of the current literature.Carwile E - J Neurosci Nurs - 01-FEB-2009; 41(1): 18-25; quiz 26-7
Also see the same controversy going on about the estrogen;
Low-dose, transdermal hormone replacement therapy (HRT) does not appear to increase the risk for stroke compared with no HRT use, according to a study published June 3 in the BMJ.
In contrast, high-dose transdermal HRT is associated with an increased risk for stroke - a risk that is at least equal to if not higher than the risks associated with oral HRT use.
There are no beneficial effect in heart disease too of estrogen;
Am Heart J. 2010 Jun;159(6):987.e1-7.
Merz CN, Olson MB, McClure C, Yang YC, Symons J, Sopko G, Kelsey SF, Handberg E, Johnson BD, Cooper-DeHoff RM, Sharaf B, Rogers WJ, Pepine CJ.
Division of Cardiology, Department of Medicine, Cedars-Sinai Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA. firstname.lastname@example.org
Please feel free for your follow up questions.