Yes, and what is medicine's theory regarding this finding?
I have a theory. (Actually it dovetails quite nicely with Pauling/Rath)
From my recent personal experience with high vitamin D in winter, and the result being an almost complete protection from illness, a protection I did not receive from mega vitamin C alone for many years, and combined with knowledge from Cathcart and others http://orthomed.com/titrate.htm that almost any illness quickly depletes tissues of vitamin C, my theory is that high vitamin D, by protecting against illness and rapid vitamin C loss, thereby protects the cardiovascular system.
One way to find out would be to analyze the same data on the basis of illness.