Blood pressure and weight predict heart failure

Ramachandran S. Vasan, of Boston University School of Medicine and colleagues studied 3,362 subjects (57 percent women) who attended routine examinations between 1969 and 1994.
The team examined the participants' blood pressure and pulse pressure and BMI measurements. BMI is the ratio of height to weight that is commonly used to determine if someone is over- or under-weight. (Like no one knows what BMI means in this day and age)
These measurements were classified as current; recent (average of all available measurements during the decade); or remote (average of all available measurements obtained 11 to 20 years before the examination).
A total of 518 subjects developed heart failure. The researchers found that recent systolic blood pressure (the higher number in a blood pressure reading), pulse pressure and BMI were all associated with the risk of heart failure. An association was also observed between heart failure and remote systolic blood pressure, pulse pressure and BMI.

518 people out of 3,362 is 15%, over 25 years (and some of the measurements weren't current, some were anywhere from 11 to 20 years old). So, if the measurements in some cases were that old, could they have changed between the time the measurements were taken and those people developed heart failure (if indeed any of them did)? And if the measurements had changed, in what direction had they changed? Did the blood pressure, pulse pressure, and BMI increase, or did they decrease? Did all 3 measurements increase/decrease, or just one or two? What affect did that have on the results? What were the family histories of the people involved in the study? Did hypertension run in their families? Had other family members developed heart failure? Nowhere in this article is any of that covered, and I would say those are all relevant factors that should be taken into consideration.

"The prevention of heart failure should begin early in life, and should include screening for elevated blood pressure and BMI," Vasan told Reuters Health. "Failure to identify or treat such modifiable risk factors in early and mid-adulthood may result in the loss of opportunities to reduce the incidence of heart failure in later life."

Failure to identify or treat such modifiable risk factors? Since when is BMI modifiable? Permanently, I mean? I would think that losing weight, only to gain it back and possibly more, would be worse than not losing it at all, even for those at risk of developing heart failure. Especially since repeated loss and gain of weight usually means muscle mass is lost first (and your heart is a very important muscle), and when weight is regained, it usually isn't muscle that is regained, it's fat. So any muscle you've lost from your heart is not going to be replaced (and wouldn't that lead to heart failure if you have hypertension to begin with?). If I'm wrong, let me know, I want to know if my conclusions are erroneous.