What can be done to
prevent stroke recurrence?

One of the most powerful risk factors for a stroke is having had one already. The odds of a recurrent stroke within a few months of an initial stroke are on the order of one in six. Each year, recurrent strokes account for about 30% of all strokes in the United States. The risk of a second stroke declines if the first year passes without incident, but it remains elevated when compared to the risk of individuals who have never had a stroke.

Not only is the risk of a second stroke higher than the risk of a first stroke, but also the consequences of a second stroke are more severe. The likelihood of death within 30 days is nearly twice as great for a second stroke as for a first stroke.

Clinically recognized strokes represent only a portion of our total stroke burden. With sensitive imaging studies, we frequently identify silent (clinically unrecognized) strokes. In fact, clinically recognized strokes may be only the tip of the iceberg. It has been estimated that small, silent strokes may be more than ten times as common as recognized strokes.

Although small, silent strokes are individually silent, an accumulation of them can give rise to clinical syndromes that are unlike what we expect from a stroke. Rather than having a sudden loss of function, one may experience a gradually progressive disorder that resembles Alzheimer's disease or Parkinson's disease. Just as clinically evident strokes are more common in patients who have had a previous stroke, so too are clinically silent strokes.

As if these realities were not sufficiently sobering, persons with a previous stroke are also at higher risk for heart attack and for sudden vascular death than are their stroke-free counterparts.

There is a silver lining in this dark cloud, however. A stroke doesn't, in itself, engender another stroke. Rather, a stroke is just a powerful marker for an elevated risk of stroke, nothing more.

A stroke is the damage caused by a failure of circulation to a part of the brain. Most often, this failure is caused by a clot that blocks an artery, but there are other ways in which the circulation can fail, and there are many risk factors that predispose to circulatory failure. Most of these risk factors are modifiable, and there is good evidence that modifying them can reduce risk. Indeed, it has been estimated that more than two-thirds of all strokes could be prevented by more effectively modifying underlying risks.

Among the most important modifiable risks are high blood pressure, heart disease (especially atrial fibrillation, a chaotic heartbeat), diabetes, high cholesterol, tobacco use, and narrowing of the carotid arteries.

A discussion of the treatment for these risk factors is beyond the scope of this column. Multiple treatment options exist, and the best treatment for a given individual is something that must be individually determined.

The take-home message is this: If you have had a stroke, it is more important than ever that you review your stroke risk profile with your doctor, and that together you craft an optimal strategy for preventing recurrence.