The main finding of our study was the improvement of QoL over a long-term period in a group of patients with typical AFl undergoing CTI ablation. This is, to the best of our knowledge, the first study to assess QoL in this population over a long-term period such as this (more than five years) and that used MID to assess QoL changes perceived by the patient. The SF-36 questionnaire is an extensively validated generic QoL measure and has been used in the study of numerous health conditions, including AFl . Unlike other studies, we also used the MID to evaluate differences in QoL. It is important to determine MID because it enables an assessment of whether typical AFl patients perceive changes in QoL produced by CTI ablation as providing enough benefit to make this treatment acceptable, in the absence of excessive cost or severe side effects, regardless of the differences determined by statistical analysis, and thereby an assessment of treatment efficacy. In addition, all scores were standardized and normalized for the Spanish population, adjusted for age and sex, which allowed our results to be compared with the Spanish general population.
Patients had a low score for all SF-36 questionnaire dimensions at baseline. After a long-term follow-up, all dimensions were higher and Physical Role, Vitality and Mental Health significantly improved; however, we only observed a significant MID for Physical Role. This is very important because it indicated that improvements in QoL after CTI ablation are not in fact perceived by the patient in long-term follow-up, except for Physical Role, suggesting that this dimension is particularly affected in AFl and CTI ablation provides an improvement after several years, although, because of its ceiling effect, we cannot know exactly the magnitude of improvement on QoL.
The baseline dimensions were very low and, probably, the existence of comorbidity factors such as DM, heart failure and osteoarthritis partly contributed to these findings. These chronic afflictions have an impact on QoL and, in fact, chronic diseases such as arthritis or osteoarthritis may condition a nine-point difference for the Physical Function dimension, and others, such as DM or heart failure, can explain a difference of up to 13 points .
Previous studies that assessed the basal QoL showed similar results [16, 17]. The baseline characteristics of our study population are comparable to other studies of AFl ablation [5, 16–18]; however, in our population there was a greater proportion of DM (20%, compared to 7–15% described elsewhere). Furthermore, these similar findings were published in relation to other arrhythmias, such as AF [17, 19, 20], which is usually better tolerated than AFl. Thus, Lönnerholm, et al.  reported a reduced basal QoL in patients with AF, both for the Physical and Mental Functions, even when values were lower than those published in the Medical Outcome Study , which included patients with symptomatic chronic left ventricular dysfunction (dyspnea, edemas,…), hypertensive patients with very severe symptoms and severe heart failure and/or stroke, patients with previous myocardial infarction and heart failure or patients with severe angina and diabetes with multiorgan involvement.
The basal dimension with the highest score was Bodily Pain, which seems not to be very important role for patients with AFl; indeed, the most common symptoms associated with AFl are palpitations, shortness of breath or occasionally heart failure and, rarely, chest pain .
At follow-up, scores were higher than baseline scores for all dimensions of health, except for Bodily Pain, the worst scores for which could be explained by an increase in age-related noncardiac comorbidities such as, for example, osteoarthritis. There was a significant difference between follow-up and baseline scores for Physical Role, Vitality and Mental Health. The improvement for Mental Health and Vitality is important because these dimensions showed neither a ceiling nor a floor effect, which means that the SF-36 questionnaire can reliably perceive positive or negative changes for these dimensions. Moreover, Vitality is an important dimension because it represents the physical and mental aspects of health. However, all scores were low in relation to the Spanish general population. It is possible that associated comorbidities could explain this finding.
Several studies in the literature [16, 17, 21–23] have described a significant and important improvement in QoL after AFl ablation in short- to medium-term follow-up. In our study, we found a smaller improvement, probably because of the longer follow-up period. Our study extends the follow up and a longer follow-up facilitates the onset of age-related comorbidities and the progression of baseline chronic diseases, such as diabetes mellitus; both phenomena are associated with an impairment on QoL. This fact can contribute to the lower QoL, regardless of the ablation procedure. Even thus, there was an improvement on long-term QoL after CTI ablation with respect to baseline QoL. So, these findings support the AFl conditions an important deterioration on QoL and the ablation provides an improvement on QoL not only in the short- to medium-term, as previously described, but also in the longer term.
The main determinants of long-term QoL that we found were the baseline QoL, AFl recurrence, the previous DM, OAC and AF. AFl recurrence often presents with high ventricular rates, which makes it a very symptomatic arrhythmia; it is more difficult to achieve an appropriate rate control using antiarrhythmic drugs. That is why this arrhythmia has an important impact on QoL. In our study, all patients with typical AFl recurrence underwent a reablation procedure, except for one individual who underwent electrical cardioversion with no more AFl clinical episodes. DM is a chronic progressive disease associated with multiple complications, and so, by the time of follow-up, the disease has progressed and complications will have appeared; this would explain why the deterioration in QoL, both for physical and mental health, was more pronounced in these patients compared to those who do not suffer from DM. It is well known that the presence of AF is associated with impaired QoL, which significantly improves when a good heart rate control or sinus rhythm is achieved. OAC is very likely to be a risk indicator in patients who receive it, indicating that it is used in patients with more comorbidities and therefore at high risk of complications and impaired QoL. In addition, the numerous controls used to optimize the dose of anticoagulant therapy in patients with restricted mobility and who live far from health centers, such as it occurs in our study population, could contribute to a loss of QoL.
So, patients that have undergone AFl ablation constituted a population presenting comorbidities that probably influenced the deterioration of QoL at baseline and at long-term follow-up. Nevertheless, ablation provided a significant improvement, chiefly for Physical Role, Vitality and Mental Health, and patients were able to perceive this improvement for Physical Role.
Finally, the questionnaire completion rate was excellent; all patients answered the questionnaire at baseline (prior to ablation procedure) and at follow-up. Therefore, there were neither blank questionnaires nor incomplete items, unlike other studies [13, 24, 25] in which the questionnaire was retrospectively completed, making it more difficult to complete and to evaluate the health status before and after a particular treatment.
This study was developed in a single hospital in Spain, so the interpretation of the results should be made with caution. More studies are needed to replicate these findings.
The SF-36 is a generic questionnaire that evaluates most of the health-related areas relevant to multiple diseases and their treatment but, as a generic questionnaire, it is not designed to assess specifically QoL related to the treatment of arrhythmias. Furthermore, there are some important health aspects that are not covered in this questionnaire, such as sleep disorders, eating disorders, familial function, sexual function or cognitive function. In addition, both the ceiling and floor effect were observed for some dimensions, probably indicating that the SF-36 is not quite sensitive and specific enough to detect changes in these dimensions after the ablation procedure.