(Circulation. 1998;98:1045-1046.)
© 1998 American Heart Association, Inc.
Prediction of Transition to Chronic Atrial Fibrillation in Patients With Paroxysmal Atrial Fibrillation
Hironosuke Sakamoto, MD, PhD;
Masahiko Kurabayashi, MD, PhD;
; Ryozo Nagai, MD, PhD
The Second Department of Internal Medicine,
Gunma University School of Medicine,
Maebashi, Japan
Jun Fujii, MD, PhD
The Institute for Adult Diseases Asahi Life Foundation,
Tokyo, Japan
To the Editor:
We read with great interest the recent report of Abe et
al1 demonstrating that P-wave–triggered
signal-averaged electrocardiography may be
useful to predict the transition to chronic atrial fibrillation in
patients with paroxysmal atrial fibrillation. In their study, although
sex, age, and presence of organic heart disease were not associated
with an increased risk for the transition to chronic atrial
fibrillation, patients with the abnormality of a P-wave–triggered
signal-averaged ECG had an 11-fold greater risk for chronic atrial
fibrillation than those without the abnormality.
Echocardiographically, left atrial dimension in
patients with chronic atrial fibrillation was larger than that in
patients with paroxysmal atrial fibrillation (40.5 versus 36.4 mm,
P<0.05), but there were no significant differences in left
ventricular dimensions measured at end diastole
and end systole or in ejection fraction between the 2 groups.
In contrast to the findings by Abe et al, we2
previously reported that congestive heart failure and reduction in left
ventricular ejection fraction were predictors of the
transition to chronic atrial fibrillation in patients with new-onset
atrial fibrillation. To identify predictors of the transition to
chronic atrial fibrillation within the first year after onset, we
retrospectively reviewed clinical records, standard 12-lead ECGs,
and M-mode echocardiograms of 137 patients with new-onset, nonrheumatic
atrial fibrillation. One year after onset, 30 (22%) of 137 patients
showed a transition to chronic atrial fibrillation, and the other 107
continued to have paroxysmal atrial fibrillation. Compared with
patients with paroxysmal atrial fibrillation, patients with chronic
atrial fibrillation were older at the time of onset (70.1 versus 62.4
years, P<0.01), more frequently had diabetes mellitus (37%
versus 19%, P<0.05), and more frequently had congestive
heart failure (13% versus 3%, P<0.05). These patients
also had higher cardiothoracic ratios on chest x-ray (52.0% versus
47.0%, P<0.01), greater f-wave amplitude in lead
V1 on ECG (1.48 versus 1.06 mm,
P<0.05), larger left atrial dimension measured by
echocardiography (41.0 versus 34.2 mm,
P<0.01), larger left ventricular
end-systolic dimension (32.9 versus 29.7 mm,
P<0.05), and lower ejection fraction (0.71 versus 0.76,
P<0.05). Furthermore, the presence of any 1 of the
following 7 factors was associated with an increased risk for the
transition to chronic atrial fibrillation: age >65 years (32% versus
11%, P<0.01), diabetes mellitus (35% versus 18%,
P<0.05), congestive heart failure (57% versus 20%,
P<0.05), cardiothoracic ratio >50% (41% versus 11%,
P<0.01), f-wave amplitude in lead V1
>2.0 mm (80% versus 20%, P<0.01), left atrial
dimension >38 mm (34% versus 5%, P<0.01), and
ejection fraction <0.76 (35% versus 4%, P<0.01). When
each of these 7 significant predictors was assigned 1 point in risk
score, the transition to chronic atrial fibrillation occurred in >88%
of the patients with a risk score >4 (a high-risk group), in 22% of
the patients with a risk score of 3 (an intermediate-risk group), and
in <6% of the patients with a risk score <2 (a low-risk group).
The discrepancy between these 2 studies may be due to patient
characteristics. Patients in the study by Abe et al were outpatients
who had maintained cardiac function relatively well, whereas our study
patients were recruited in part from an inpatient population with more
congestive heart failure or moderate to severe cardiac dysfunction.
This suggests that P-wave–triggered signal-averaged
electrocardiography is useful to predict the
transition to chronic atrial fibrillation, especially in patients with
normal cardiac function. On the other hand, in the population including
patients with impaired cardiac function, we propose that congestive
heart failure and reduced left ventricular ejection
fraction are important predictors of the transition to chronic atrial
fibrillation. Furthermore, the major advantage of our proposed
predictors and risk scoring system is that they allow physicians to
identify patients with new-onset atrial fibrillation at high risk for
the transition to chronic atrial fibrillation using routinely available
clinical parameters.
References
1.
Abe Y, Fukunami M, Yamada T, Ohmori M, Shimonagata T,
Kumagai K, Kim J, Sanada S, Hori M, Hoki N. Prediction of transition to
chronic atrial fibrillation in patients with paroxysmal atrial
fibrillation by signal-averaged
electrocardiography: a prospective study.
Circulation. 1997;96:2612–2616.[Abstract/Free Full Text]
2.
Sakamoto H, Okamoto E, Imataka K, Ieki K, Fujii J.
Prediction of early development of chronic nonrheumatic atrial
fibrillation. Jpn Heart J. 1995;36:191–199.[Medline]
[Order article via Infotrieve]
Response
Masatake Fukunami, MD;
Yasushi Abe, MD;
; Noritake Hoki, MD
Division of Cardiology,
Osaka Prefectural Hospital,
Osaka, Japan
We appreciate the interest shown by Dr Sakamoto and his
colleagues in our article1 and their valuable
comments using their results. They raised some important issues on
prediction of transition to chronic atrial fibrillation. They proposed
their risk-scoring system using 7 predictors from clinical
parameters, including indexes of heart failure, which
proved to be significant in their retrospective
study.2
As they pointed out, the discrepancy between their and our results may
be derived mainly from the difference of study population; study design
(prospective or retrospective) may be also involved. Unfortunately, we
have not yet conducted studies on the usefulness of P-wave
signal–averaged electrocardiography for
prediction of transition in patients with reduced cardiac function.
However, we recently found that filtered P-wave duration prolongation
can be a direct predictor of hospitalization for worsening heart
failure in a prospective heart failure
study3 , in which Kaplan-Meier
analysis revealed that patients with heart failure (ejection
fraction <40%) who had an abnormally prolonged filtered P wave (
145
ms) were more often (29% versus 4%, log-rank test P<0.05)
hospitalized for worsening heart failure than those without it during
the follow-up period of 1 to 37 months. In addition, atrial
fibrillation was often observed on admission. This implies that
filtered P-wave duration may be an early predictor of heart failure
deterioration as well as the establishment of atrial fibrillation. It
is also well known that atrial fibrillation itself causes a
deterioration in cardiac function, probably due to the disappearance of
atrial contraction and shortening of the diastolic phase,
although heart failure itself enhances the accomplishment of atrial
fibrillation. Consequently, the mechanism for establishment of atrial
fibrillation may be complicated in heart failure patients, in whom
changes in autonomic nerve system, electrolytes, humoral factors, and
hemodynamics often occur. In general, most clinical
parameters are redundant and depend in part on each other.
That is why the analysis had to be complex, especially in a
prospective study. Subsequently, to make it simpler, we investigated
only filtered P-wave characteristics, such as
electrophysiological arrhythmogenic
substrate, in patients without heart failure. Although the left atrial
dimension and the number of atrial premature contractions a day were
weakly but significantly different between the 2 groups with and
without the transition in our study, we think that this might be
because they were closely related to the filtered P-wave
duration.
Many people would like to know what type of paroxysmal atrial
fibrillation will eventually change to the chronic form because the
prognosis and incidence of thromboembolism are different. Thus, we
would like to propose again that P wave signal–averaged
electrocardiography be used in patients without
heart failure. If additional criteria in P-wave signal–averaged
electrocardiography for patients with heart
failure are proposed, our method will be more applicable in
clinics.
References
1.
Abe Y, Fukunami M, Yamada T, Ohmori M, Shimonagata T,
Kumagai K, Kim J, Sanada S, Hori M, Hoki N. Prediction of transition to
chronic atrial fibrillation in patients with paroxysmal atrial
fibrillation by signal-averaged
electrocardiography: a prospective study.
Circulation. 1997;96:2612–2616.
2.
Sakamoto H, Okamoto E, Imataka K, Ieki K, Fujii J.
Prediction of early development of chronic nonrheumatic atrial
fibrillation. Jpn Heart J. 1995;36:191–199.
3.
Asano Y, Fukunami M, Shimonagata T, Kumagai K, Yamada
T, Sanada S, Ogita H, Hoki N. Signal-averaged P-wave duration: as a
predictor for the deterioration of heart failure. J Cardiac
Failure. In press.
