Cardiac pacing has developed into a technically reliable and efficient treatment for patients with bradycardic heart diseases. Randomized controlled trials have been done documenting the efficacy of this treatment with respect to improvement in quality of life and reduction in morbidity as well as to which pacing mode to select. However, in each centre performing pacemaker implantations, a continuous work still should be done aiming at improvement of treatment quality and at reducing side effects and complications. For this purpose, the regular feedback from obligatory well-organized quality control programmes is invaluable.
Nowak et al.1 present a study of the effect of patient gender on pacemaker implantation based upon analysis of pre- and peri-operative data from a cohort of 17 800 consecutive patients undergoing primary pacemaker implantation and reported as part of an obligatory external quality control programme. Some very interesting findings regarding pacing mode selection and complications of pacemaker treatment appeared in this analysis.
A surprisingly high percentage of patients received a single-lead ventricular (VVI) pacemaker system instead of a physiological pacemaker system that preserves synchrony between the atria and the ventricles. More women than men were treated with VVI pacing. Restricting the analysis to patients treated in small centres performing less than 20 pacemaker implantations per year, the gender differences were extreme, with 60% of women receiving VVI devices vs. 45% of men, but still in the remaining larger centres as many as 39% of women and 33% of men were treated with VVI devices. In the elderly population, significantly more women than men received VVI pacemaker systems, both in those who had atrio-ventricular (AV) block and those with sick sinus syndrome (SSS) as an indication for pacemaker implantation. In these patient categories, a total of 27–29% of women and 21–23% of men aged 80–89 years and as many as 60–62% of women and 41–48% of men aged 90 years or more were treated with VVI pacing. Among younger patients, fewer received VVI devices, and no significant differences were observed between genders. According to the ESC guidelines on cardiac pacing, dual-chamber pacing with programming aimed at reducing ventricular pacing or alternatively single-lead atrial pacing for selected patients is the recommended pacing mode for SSS, whereas ‘VVI pacing alone can no longer be recommended’. 2 For patients with AV block, dual-chamber pacing is the recommended pacing mode while rate-adaptive VVI pacing ‘could be an alternative, especially in patients who have a low level of physical activity and in those with a short expected lifespan’. The present analysis therefore documents a clinically significant non-adherence to guidelines for pacing mode selection resulting in more patients being treated with a less good VVI pacemaker system. This non-adherence to guidelines was more distinct in women than in men, especially in the elderly patients.
Among patients with SSS, it has been clearly demonstrated in randomized trials that VVI pacing increases the risk of atrial fibrillation, 3 and in a meta-analysis, VVI pacing was found also to increase the risk of stroke. 4 Dual-chamber pacing increases quality-adjusted life-expectancy in patients with SSS at a cost that is generally considered acceptable. 5 Admittedly, pacing mode selection has to be individualized for each patient, and the recommended pacing mode cannot be used for every patient. However, the use of VVI pacing in patients with SSS or AV block can be reduced to a stable level of 10–15% of patients as documented in the Danish Pacemaker Register. 6 The difference observed between men and women regarding the pacing mode selection has not been found in previous large cohort studies. 7 , 8 The reason for this difference among genders is largely unknown. Similar durations of implantation and fluoroscopy in male and female patients indicate that other reasons than any technical/surgical differences between the two genders have to be searched for. Older age and co-morbidities as well as physicians selection bias were suggested to play a role. Socio-economic reasons may have contributed. Older age is independently associated with atrial fibrillation and stroke, and therefore per se should not be regarded an excuse for selecting VVI pacing to patients with SSS increasing these risks even more. Especially not in women, who in mean lives longer than men after their pacemaker implantation, despite an older age at the time of implantation.
The present analysis underlines the importance of constantly running an obligatory external quality control programme in cardiac device therapy. Only by the use of such a programme is it possible to detect the degree of adherence to guidelines as well as any systematic imbalances as the present difference detected between genders. The results should be used to improve future quality in pacemaker treatment. An additional prospective registration of the reason for deviating from the recommended pacing mode may be used for this purpose in future quality control programmes. This parameter is recorded, for example, in the Danish Pacemaker Register 6 whenever another pacing mode than the recommended mode is chosen. Such a requirement may increase physicians' attention to the importance of an appropriate pacing mode selection and to the adherence to guidelines in both women and men.
Another important finding from the quality control programme was the association between the rate of acute complications of pacemaker implantation and the gender. The complication rates were similar to rates reported from other large quality databases, 6 , 9 indicating a sufficiently high surgical/technical quality in the centres participating. The finding of a higher rate of complications among women, significant overall and with respect to pneumothorax and pocket haematoma, has not been reported before. These results are very similar to findings recently reported in a large study on patients receiving an implantable cardioverter-defibrillator (ICD). 9 The reasons for these gender differences are not known. In the present study, durations of procedures and fluoroscopy were identical in men and women as were the rates of subclavian vein puncture. Therefore, it seems unlikely that the surgical procedures in general were more difficult in the female than in the male patients. It is likely that anatomical differences between genders may play a role and predispose women to some of these complications such as pneumothorax.
Detection of gender differences with respect to complications to pacemaker implantations—also in this case does the obligatory external quality control program prove its value. Such a quality control programme is the only way to follow real-life complication rates regularly and to intervene if the rates exceed a given standard, thereby improving device therapy. The present findings on gender differences in complication rates will increase attention on how to avoid device-related complications, but should also result in a recording of additional data potentially related to complications in the future quality control programme, e.g. body mass index and treatment with anticoagulation/antiplatelet drugs followed by another analysis of complications and gender.
It should be kept in mind that recording of complications to device therapy in obligatory external quality control programmes are based upon self-reporting from the implanting centres, and such rates therefore represent minimum values. Regular external audit should be used to ensure a sufficiently high accordance between complications reported in hospital files and reported to the quality control programme.
In conclusion, the report by Nowak et al. represents an excellent example of how results from an obligatory external quality control programme may disclose important data on the real-life quality in device therapy. 1 It should be mandatory for all clinics performing pacemaker and/or ICD implantations to participate in a similar quality control programme to continuously document their quality in treatment and to improve this quality. Participants should be encouraged to publish their results as done by Nowak et al.1 to allow other centres implanting devices to use this information improving their own quality control programme.
Conflict of interest: none declared.