Although PAF is one of the most common heart-disturbances causing patients to get in touch with medical care centres, surprisingly little information is available about the factors which trigger it and the symptoms associated with the onset of arrhythmia in larger groups of patients. This study has therefore been undertaken to determine which factors patients consider responsible for triggering arrhythmia and the symptoms that occur in connection with episodes of arrhythmia.
What provokes arrhythmia?
From observations of heart-rate in sinus rhythm shortly before its onset, a separation of PAF into sympathetically-mediated and vagal forms has been suggested . Earlier studies have shown a degree of daily variation in the onset of AF. Thus, attacks are more common in the morning and at night , but higher frequency has also been reported during daytime . A possible explanation is that arrhythmia often starts in younger patients at night and in older ones during the day . A weekly variation has also been reported, with fewer attacks on Saturdays . An annual variation with fewer attacks during the last months of the year has also been reported .
In our study, the 72 patients who thought that their attacks of arrhythmia usually occurred at about the same time of day gave this as the evening or at night. Hence a large fraction of those investigated should have vagal PAF since this often starts at night . Despite this, the majority of the patients considered that the triggering-factor was some kind of situation in which increased levels of catecholamines can be discerned. Even those with positive stress-related anamnesis (triggered by physical exertion and psychic stress) had often attacks starting in the evening or at night. However, this need not imply an absolute correlation in time, but rather the probable existence of a certain latent period between stress and the onset of arrhythmia. In earlier studies, it has been proposed that attacks of PAF are often due to variations in the tonus of the autonomic nervous system. Arrhythmia is stimulated particularly when an initial adrenergic increase is followed by an abrupt change to vagal dominance .
Alcohol has long been considered to play an etiological role in PAF, a correlation underlined in the expression "holiday heart" . Since temporary enhanced alcohol consumption is frequent, it is difficult to prove a direct correlation [8, 16]. Episodes of AF have been triggered by the acute effects of alcohol on atrial refractoriness and conduction, but also by the effects of chronic misuse of alcohol leading to subclinical heart dysfunction . Other mechanisms have also been discussed . Every third patient in our study considered alcohol to be a triggering-factor, but white wine was blamed less than red wine and spirits. Why arrhythmia should be triggered less frequently by white wine than by red wine or spirits remains unclear.
It is now generally accepted that most attacks of PAF are induced by ectopic impulses originating in the pulmonary veins [19, 20]. Both automaticity and triggered automaticity in these cells have been demonstrated in experimental conditions [19, 20]. The influence of the autonomic nervous system, alcohol and other factors inducing arrhythmia on this mechanism is, however, uncertain.
Symptoms at the onset of fibrillation
Although a number of patients with PAF are without any symptoms , in general patients with this form of arrhythmia show more symptoms than those with permanent AF . Studies with telephone-transmitted ECG have, however, shown a sensitivity of symptomatic registrations of up to 89% with PAF . There is thus good correlation between the symptoms and ECG-verified AF.
The limited amount of literature on the symptomology of PAF includes Quality of Life investigations, Case Reports and quantification of a few symptoms . Investigations based on "Quality of Life" forms have earlier shown that patients with PAF have lower scores for physical function, emotional function, vitality and general health . The symptoms commonly reported include palpitations, giddiness, dyspnoea, tachycardia, perspiring, chest pains, coldness, anxiety [23–25], tiredness, weakness, indisposition, vomiting and epigastrical discomfort .
The most frequent symptoms in periods of AF reported by our group of patients included palpitations, reduced physical performance, palpitations when at rest, breathlessness when exerting oneself and anxiety. In an earlier report, the most pronounced symptoms were palpitations and anxiety as well as giddiness . That females showed significantly higher frequencies of swollen legs, indisposition and anxiety than males has not previously been reported. These differences can possibly be accounted for since earlier studies have reported that attacks of AF in women last longer and cause higher heart-rates . We could not, however, establish any significant differences in the lengths of attacks between men and women in our material.
Swollen legs can also be accounted for due to right-sided cardiac failure in some patients. That most patients experience definite symptoms following acute but transient attacks of AF can possibly depend on the increased activity of the sympathetic nervous system triggered by an attack of AF . It is plausible to assume that the autonomic nervous system plays a considerable part in both the genesis of and the symptoms observed during a period of AF .
This material was taken at a hospital and is thus not representative of all patients with PAF. The symptoms of our patients are so far advanced that hospitalization or a visit to a hospital was required. Ongoing treatment can have modified patients' recollections of anamnestic factors. The material was not taken consecutively, but randomness was favoured by lack of a systemic inclusion mechanism.
Patients with hypertension are not excluded, even if subtle diastolic changes in the left ventricle and hence the left atrial performance could be caused by hypertension .
Although symptoms associated with the onset of PAF may be age related, the present material is too limited to allow exploration of this relation.