Stroke Occurring with Atrial Fibrillation: Likely to be Fatal or Severe

ABSTRACTS & COMMENTARY

Sources: Lin H-J, et al. Stroke severity in atrial fibrillation. The Framingham Study. Stroke 1996;27:1760-1764; Jorgensen HS, et al. Acute stroke with atrial fibrillation: The Copenhagen Stroke Study. Stroke 1996;10:1765-1769.

Atrial fibrillation (AF) is the most prevalent chronic cardiac arrhythmia in the elderly and increases the risk of stroke as much as five-fold. Whether the strokes that occur in patients with AF also are more serious than those in non-AF stroke patients has been uncertain. Two recent community-based studies confirm that acute stroke patients with AF had both a higher mortality rate and a poorer functional status than stroke patients without AF (see Table).

The Framingham researchers found that stroke patients with AF had a higher mortality, more stroke recurrences, greater severity, and poorer functional status than those without AF. The poorer outcome in AF subjects was reflected in the high early mortality rate. The significantly higher 30-day mortality in AF-associated strokes (see Table) was similar to that in previous reports. Stroke was more lethal in older subjects, and, in fact, one-half of the strokes in AF patients 75 years of age or older were either severe or fatal. Overall, acute stroke severity was significantly greater in AF-associated stroke (see Table). Nearly three-quarters of acute AF stroke patients were severely disabled, compared with only one-third of non-AF patients. The difference in functional status between AF and non-AF patients decreased over time and by 12 months after strokes was not statistically significant. This decrease in difference is likely due to the poorer survival of AF subjects during the follow-up period (more died) and the higher functional performance and higher Barthel Index (BI) scores of the AF stroke survivors.

Table

Clinical characteristics of stroke patients

Framingham Study* Copenhagen Study**
AF Non-AF AF Non-AF
n 103 398 217 965
Age (years) 75±1 71±0.5 80±8 73±11
Mortality n (%) 26 (25) 56 (14)£ 72 (33) 171 (17)£
Acute BI 29.6±6.9 58.6±3.5£ 34.5±39.1 51.7±41.3£
Outcome BI 64.3±10.7 80.3±4.0º 66.8±38.0 78.0±3.3º
Note values given as:
* mean + SEM; ** mean + SD; £ P < 0.001; º NS

The Copenhagen physicians found that AF patients had higher mortality rates, more severe strokes, longer hospital stays, and a lower rate of discharge to their own homes. In this study, the functional level was significantly lower in AF stroke patients acutely and also much later when they were discharged from rehabilitation (see Table), although the authors do not give the average time in months to this event.

On CT scan, AF patients had larger cerebral infarcts and had an infarct from a previous stroke more frequently. Leukoaraiosis was less frequent in AF patients. Interestingly, stroke in evolution or progressive stroke and recurrent stroke during the acute hospital stay occurred with equal frequency in AF and non-AF patients.

COMMENTARY

Both these studies support the conclusion that AF leads to emboli that occlude large cerebral arteries leading to severe strokes. The Copenhagen study found that patients with AF more often had large cortical infarcts on CT and less frequently had small subcortical infarcts. Chronic AF also was not associated with diffuse cerebral small vessel disease.

Since stroke is usually the initial manifestation of embolism in AF, primary prevention of stroke with warfarin anticoagulation in AF patients seems indicated. Proper anticoagulation treatment can safely prevent the majority of embolic strokes in AF patients. Nevertheless, because most individuals with AF are old, and many are older than 80 years, many physicians are reluctant to institute anticoagulation. The poor outcomes reported in these two studies indicate that prevention of the first AF-caused stroke had a substantial benefit that outweighs the risks.