CHRONIC DISEASE

Persistent lone atrial fibrillation its prognosis after clinical diagnosis .

J. B. CLOSE, b.scmrcp, D. W. EVANS, ma,md,b.sc,frcp,dch, and S. M. BAILEY, mb,bs SUMMARY. Eighty-three patients whose atrial fibrillation appeared to be permanent and the sole cardiac abnormality at the time of diagnosis were followed for one to 19 years (mean 7-5 years). None suffered systemic embolism. Three died, none of cardiac disease. Sinus rhythm re¬ turned in seven. Another six developed features suggestive of other heart disease. In the remain¬ ing 67, the initial diagnosis of persistent lone atrial fibrillation remained tenable and they re¬ mained well. The medium-term prognosis for patients with this disorder seems good.

Aims The first aim of the study was to see how well the initial diagnosis stood the test of time. Since it was based on simple clinical evidence, without specialized investi¬ gations, it was expected that some with cryptic heart disease might be misdiagnosed ione fibrillators' in¬ itially, the true state of affairs becoming evident sub¬ sequently. Were this to prove common, then prognostic caution would clearly be justified. The second and main aim was to assess the liability of those with defined persistent lone fibrillation to cardiac death or disability, with particular regard to the risk of systemic embolism.

Introduction

Method

rPHE need for this study was suggested by evidence -¦¦ of a restrictive attitude in the management of pa¬ tients with longstanding lone (idiopathic) atrial fibrilla¬ tion, particularly about their fitness to drive. This attitude was held to be justified by authoritative state¬ ments alleging a six per cent risk of embolism (Wood, 1968) and the rarity of the permanent dysrhythmia in isolation (Braunwald and Sobel, 1974). Our experience conflicted with these statements. We therefore decided to document the progress of a defined population in whom the initial diagnosis of persistent lone atrial fibrillation had been made on clinical grounds, there being no demonstrable cause, associated cardiovascular disease, or cardiac enlargement at that time. For exclusion of still-paroxysmal forms, which may carry a different prognosis, we relied on the continuous presence of the dysrhythmia for a week or more before diagnostic categorization (Phillips and

Eight hundred of the inpatients and outpatients seen by staff of the East Anglian Regional Cardiac Unit be¬ tween 1959 and 1976 were indexed as having atrial fibrillation. Their records were scrutinized to determine the assigned aetiology (Table 1) and 86 (nine per cent) were categorized as having persistent lone atrial fib¬ rillation after failure to find an underlying cause or evidence of other cardiac disease. These patients formed the study group. None of them had cardiac enlargement on x-ray or any ECG abnormality other than the dysrhythmia which had been present without detected interruption for at least seven days. There were 12 women, aged 50 to 76 years (mean, 63 years) at first presentation and 74 men, aged 20 to 79 years (mean, 52 years). Fifty-seven (77 per cent) of the men were aged from 40 to 69 years. Follow-up in¬ formation was obtained for 83 patients (97 per cent), 40 by personal interview and examination (J.B.C.) and the remainder from the general practitioner or hospital records. For those seen personally, details included plasma cholesterol and (fasting) triglyceride concen¬ trations, serum tri-iodothyronine, chest x-ray, and resting 12-lead electrocardiogram. Information on 39 patients was obtained from a questionnaire sent to their general practitioner, and from scrutiny of their hospital notes. Three were re-

Levine, 1949).

J. B. Close, Medical Registrar, St Thomas' Hospital, London; D. W. Evans, Consultant Cardiologist, Cambridgeshire Area Health Au¬ thority; S. M. Bailey, Clinical Research Assistant, East Anglian

Regional Health Authority.

© Journal of the Royal College of General Practitioners, 1979, 29, 547-549.

Journal ofthe Royal College of General Practitioners, September 1979

547

Chronic Disease Table 1. Aetiology of atrial fibrillation in 800 patients with this dysrhythmia seen between 1969 and 1976.

Rheumatic heart disease

275

Hypertension/ischaemia 200 Lone (idiopathic) paroxysmal 119 Lone (idiopathic) persistent 86 Thyrotoxicosis 30 Congenital heart disease 18 Cardiomyopathy 18 Myocarditis/pericarditis 14 Other (e.g. post-operation, pulmonary embolism, cor pulmonale)

40

Total

800

Table 2. Cause and age of death after diagnosis of persistent lone atrial fibrillation (PLAF). Time from

diagnosis of PLAF

Sex Age Female 79

to death

4 years

Cause of death Carcinoma of Carcinoma of

Male

46

2 years

Male

65

4 months

Necropsy No

stomach Yes

bronchus

Pulmonary embolism. Deep vein

Yes

thrombosis. Pontine

infarction. Basilar artery thrombosis

ported by their practitioners

to be in sinus rhythm. Chest x-ray reports and ECG traces were examined in all cases. Serum cholesterol was available in 21 cases. All were normal. Tests of thyroid function had not been performed routinely. One patient was diagnosed thyrotoxic six months later. Only four practitioners failed to return the ques¬ tionnaire. Information was obtained from these pa¬ tients' notes only. All had been followed up for more than four years. They had last been seen between three and seven years previously. The Registrar of Births and Deaths ascertained that none had died. Three patients were lost to follow up. None had died.

Results Three years

patients had died between four months and four (mean, 21 months) after diagnosis. Necropsy

details were available for two. Cause and age of death are shown in Table 2. In two cases death was due to neoplasia, and in the third, basilar arterial thrombosis and pulmonary embolism, but there was no evidence of systemic embolism and the heart was found to be normal. The haemoglobin, white blood count, urea, electrolytes, blood glucose, serum albumin, and serum 548

tri-iodothyronine were normal for all. Duration of follow-up for the 80 traced survivors ranged from one to 19 years (mean, 7-5 years). Seven were found to have reverted to sinus rhythm within three to 15 months. The remainder were taking digoxin and four were also on warfarin. All were active in the context of their years. None had developed evidence of valvular disease. None had diastolic blood pressure in excess of 95 mm Hg. One, a woman of 40 years, became overtly thyrotoxic within six months and underwent thyroidectomy. One, a man of 57 years, developed angina and suffered myocardial infarction 10 years after diagnosis of lone atrial fibrillation. None reported symptoms suggestive of embolism. Three developed cardiothoracic ratios (on x-ray) above 50 per cent. Mean frontal QRS axis deviation to 30° was found at routine electrocardiography in one. Three had plasma cholesterol concentrations above 6*5 mmol/litre (250 mg/100 ml), the values ranging from 71 to 10-1 mmol/litre (274-390 mg/100 ml). Plasma triglyceride and serum tri-iodothyronine concentrations were normal in all.

Discussion A working diagnosis of lone atrial fibrillation is made in the absence of demonstrable cardiac or extracardiac disease known to cause or be associated with this dysrhythmia and in the presence of otherwise normal electrocardiographic and radiographic appearances (Hanson and Rutledge, 1949; Evans and Swann, 1954). In this study, the established (persistent) form of the dysrhythmia proved less common than the clearly par¬ oxysmal but was nevertheless thought to be present in nine per cent of all those with atrial fibrillation seen at this unit or in its clinics. There was a predilection for men in their fifth and sixth decades, as in other series

(Willius and Thomas, 1941; Phillips and Levine, 1949). The initial diagnosis stood the test of time in the great majority of cases. Seven of the 86 proved not to have truly persistent atrial fibrillation in that they subse¬ quently (and spontaneously) regained sinus rhythm, albeit at three or more months after first diagnosis. Another two may have been misclassified in that they developed overt coronary disease and hyperthyroidism respectively, during the follow-up period. Malignant disease was the cause of two of the deaths and arteriosclerosis was involved in the third, although the heart itself was found to be normal. Some cardiac enlarge¬ ment was noted in three of the survivors and these, like the one who developed left axis deviation, may have some generalized myocardial disorder. There was no instance of systemic embolism and none of the survivors had disabling symptoms, although exertional palpitation was a common complaint. Four were taking warfarin but there now appears to be no indication for anticoagulant therapy in these patients. Electrical reversion is no longer advised because of

Journal ofthe Royal College of General Practitioners,

September 1979

Chronic Disease

disappointing long-term results (Bjerkelund and Orning, 1968; Radford and Evans, 1968; Szekely et al., 1970; Waris et al., 1971). The only treatment necessary was enough digitalis to control exaggerated exertional and emotional tachycardia; even this therapy may not be needed in the elderly with naturally slow ventricular response (Martin, 1977). On the basis of this and published experience (Willius and Thomas, 1941; Phillips and Levine, 1949; Evans and Swann, 1954), persistent lone atrial fibrillation is a benign disorder and should pose no special problem in relation to driving. Indeed, the presence of this chronic dysrhythmia is evidently no bar to continuing validity of flying licences in the USA (Busby and Davis, 1976).

JOURNAL PUBLICATIONS The following have been published by the Journal of the Royal College of General Practitioners and can be obtained, while still in print, from the Royal College of General Practitioners.

REPORTS FROM GENERAL PRACTICE

Conclusion A diagnosis of established lone atrial fibrillation, made on persistence of the dysrhythmia for at least a week and absence of other cardiac disorder or obvious cause, is likely to remain tenable during protracted follow-up. The prognosis appears benign, no instance of cardiac death or systemic embolism having occurred in this large series.

References Bjerkelund, C. & Orning, 0. M. (1968). An evaluation of DC shock treatment of atrial arrhythmias. Acta Medica Scandinavica, 184, 481 491. Braunwald, E. & Sobel, B. E. (1974). In Harrison's Principles of Internal Medicine. (Ed. Wintrobe, M. M. et al.) 7th edition. Tokyo: McGraw-Hill. Busby, D. E. & Davis, A. W. (1976). Paroxysmal and chronic atrial fibrillation in airman certification. Aviation, Space and Environmental Medicine, 47, 185-186. Evans, W. & Swann, P. (1954). Lone auricular fibrillation. British Heart Journal, 16, 189-194. Hanson, H. H. & Rutledge, D. I. (1949). Auricular fibrillation in normal hearts. New England Journal of Medicine, 240, 947953. Martin, A. (1977). Atrial fibrillation in the elderly. British Medical Journal, 1, 712. Phillips, E. & Levine, S. A. (1949). Auricular fibrillation without other evidence of heart disease: cause of reversible heart failure. American Journal of Medicine, 7, 478-489. Radford, M. D. & Evans, D. W. (1968). Long-term results of DC reversion of atrial fibrillation. British Heart Journal, 30, 91-96. Szekely, P., Sideris, D. A. & Batson, G. A. (1970). Maintenance of sinus rhythm after atrial defibrillation. British Heart Journal, 32, 741-746. Waris, E., Kreus, K. E. & Salokannel, J. (1971). Factors influencing persistence of sinus rhythm after DC shock treatment of atrial fibrillation. Acta Medica Scandinavica, 189, 161-166. Willius, F. A. & Thomas, J. D. (1941). Prognosis of auricular fibrillation of undetermined origin. Journal of the American Medical Association, 117, 330-332. Wood, P. (1968). Diseases of the Heart and Circulation. 3rd edition. p. 279. London: Eyre & Spottiswoode.

Acknowledgements We thank the many general practitioners who kindly provided information about follow-up, Dr H. A. Fleming for allowing us to study some of his patients and Dr L. Reese, at St Bartholomew's Hospital, for the tri-iodothyronine assays. S. M. B. is in receipt of a clinical research grant from the East Anglian Regional Health Authority.

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