Introduction: Permanent pacemaker (PPM) implant is a well-established treatment to reduce morbidity in patients with symptomatic sinus node dysfunction (SND). Common symptoms of shortness of breath on exertion, fatigue, dizziness and syncope can be incredibly disabling. When we consider its increased prevalence in the elderly, where falls and deconditioning are leading drivers of mortality, the importance of timely intervention is clear. We hypothesised that early intervention before hospital admission could be beneficial in reducing overall mortality. We investigate this by comparing mortality data between patients receiving inpatient (IP) and outpatient (OP) implants.
Methods: This was a single-centre, observational study. We included patients who had either a single or dual chamber PPM implanted for SND between 1 January 2016 and 1 November 2020. Patients were excluded if they had any degree of atrioventricular block. Clinical information was entered at the time of implant into our institution’s electronic records database. This system is linked to the Office for National Statistics mortality records allowing us to extract all necessary data for analysis. Survival analysis was conducted using Kaplan–Meier (KM) plots and survival compared using the log-rank test. Univariate Cox proportional hazard regression analysis (CPhM) was used to assess the prognostic value of prespecified demographic, symptom, comorbidity and implant-related metrics.
Results: A total of 1,269 patients were included in the analysis: 740 (58%) OPs and 529 (42%) IPs. Cohorts were similar in age (OP 76 ± 9 years vs IP 77 ± 11 years; p=0.12) and gender (female OP 338 [46%] vs IP 245 [46%]; p=0.82). IPs had more syncope (IP 303 [57%] vs OP 269 [36%]; p<0.001) and ischaemic heart disease (IHD; IP 125 [24%] vs OP 125 [17%]; p<0.05). Implant complication rate was non-significantly higher in OPs (OP 32 [4.3%] vs IP 15 [2.8%]; p=0.17). KM survival analysis (Figure 1) demonstrated worse survival in IPs, with significantly different survival curves (p<0.001). CPhM analysis of 1-year all-cause mortality demonstrated IP implant (HR 3.25, 95% CI 1.92–5.50; p<0.001), presence of IHD (HR 2.22, 95% CI 1.10–4.51; p<0.001) and age (HR 1.11, 95% CI 1.07–1.15; p<0.001) were significant predictors of mortality. Symptoms of presyncope (HR 1.13, 95% CI 0.70–1.85; p=1.13) and syncope (HR 1.29, 95% CI 0.78–2.11; p=0.32) were not.
Conclusions: Our study highlights the morbidity associated with SND, with a significant proportion of patients requiring hospital admission. Importantly, we demonstrated IP implant is strongly associated with increased all-cause mortality, representing a worse prognostic marker than age or IHD. This supports our hypothesis that intervention before development of debilitating symptoms necessitating admission is beneficial in these patients. It may be considered that admission is correlated with a patient’s functional reserve (i.e. the frailer patient is likely to manifest more significant symptoms with less ability to manage within the community). As such, IP implant will inevitably be associated with higher mortality. Indeed, we do not suggest that SND is a direct cause of mortality in these patients, rather a leading driver of this deconditioning. Identification of these vulnerable patients to facilitate earlier intervention is likely to be of significant benefit. The clinical application of this is challenging. However, we suggest consideration of a patient’s frailty score may be of value and aim to investigate this with future prospective work. ❑