Lone Atrial Fibrillation in the Elderly
Abstract & Commentary
Synopsis: Lone atrial fibrillation after age 60 years indicates a higher risk of cardiovascular events that may be preventable with anticoagulation therapy.
Source: Kopecky SL, et al. Arch Intern Med 1999; 159:1118-1122.
Lone atrial fibrillation (af) is usually defined as AF in the absence of structural heart disease and systemic hypertension. Patients with lone AF younger than age 60 years have a low embolic risk such that anticoagulant therapy is not warranted. However, the embolic risk in lone (L) AF patients older than age 60 years is less clear. Thus, Kopecky and colleagues at the Mayo Clinic studied 55 LAF patients aged 61-97 years, which represented 2% of patients with a diagnosis of AF seen at the Mayo Clinic between 1950 and 1980. Another 55 age- and sex-watched patients served as controls. The primary events analyzed were survival and survival free of stroke over a median follow-up of 10 years. A secondary end point was survival free of thromboembolic and other cardiovascular events. In 26 of the 55 patients, 31 events occurred 0.7-18 years (median, 5) after diagnosis: seven myocardial infarctions (MI), six transient ischemic attacks (TIA), five strokes, and four pulmonary emboli. The event rates per person-year were 2.6% MI, 1.1% TIA, and 0.9% stroke for a total of 5% per person-year for these three events. The event rates in the control group were 1.1% MI, 0.2% stroke, and no TIAs for a total of 1.3% per person-year (P < 0.01 vs LAF patients). Despite the marked difference in cardiovascular event rates, survival was similar in the LAF patients vs. controls (80% at 5 years vs 89%, and 57% at 10 years vs 68%, respectively; P = 0.20). Only nine LAF patients received warfarin and six had embolic events before it was started. Only four patients were on chronic aspirin therapy. Kopecky et al conclude that LAF after age 60 years indicates a higher risk of cardiovascular events that may be preventable with anticoagulation therapy.
Comment by Michael H. Crawford, MD
Although LAF is infrequent among AF patients older than 60 years, it is an important group that physicians have not wanted to harm with treatment. This study clearly shows that they are at increased risk of cardiovascular events (four- and fivefold) over age- and sex-matched controls without AF. Thus, LAF seems to be a marker for occult cardiovascular disease in those older than 60 years. These results are supported by other trails using somewhat different patient populations. Older age increased risk fourfold in the Framingham study, which included patients with treated hypertension. In the Stroke Prevention Atrial Fibrillation (SPAF) study, patients younger than 60 years with LAF had no events.
The real issue is how to treat such patients. Obviously, if any risk factors for atherosclerosis are present, these should be treated vigorously. Beyond that, the issue is aspirin vs. warfarin. The SPAF data suggest that warfarin is superior at preventing strokes in patients with AF, especially at older ages. However, since some of the events were MIs, perhaps aspirin is indicated as well. A prospective treatment trail would be required to answer these questions, but will probably never be done in this small group of patients. Thus, at this time patients with LAF older than 60 years should probably be treated with warfarin and low-dose aspirin (81 mg/d) unless there are contraindications to this approach. Also, the development of other risk factors for stroke such as hypertension, heart failure, cerebrovascular events, or women older than 75 years would further reinforce the decision for warfarin therapy.
The above discussion is predicated on the persistence or recurrence of AF. In patients without structural heart disease, getting them into sinus rhythm and keeping them in it should be attempted. If sinus rhythm is achieved, the conservative approach is to keep them on aspirin and warfarin, but some would drop to just aspirin after a month of sinus rhythm. Although details about cardioversion attempts are not given in this paper, we do know that the majority of the patients had chronic AF, but 40% had one episode or recurrent AF. So the patient breakdown does not support a less aggressive approach.
Lone atrial fibrillation in those older than 60 years should be treated with:
a. warfarin.
b. aspirin.
c. All of the above
d. None of the above
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