While most people still think of cardiovascular trouble as primarily afflicting men, the reality is that heart disease has never discriminated between the sexes. In fact, for a variety of complex reasons, the condition is more often fatal in women than in men - it is also more likely to leave women severely disabled by a stroke or congestive heart failure. The common belief that pre-menopausal women are immune to heart problems is simply wrong. Which of the following, if true, would most strengthen the argument?