Discussion
In the present study, the cumulative rate of progressive TR ranged from 1.3% in the first year to 18.4% in the sixth year. Higher pre-implant TRPG and larger post-implant LA dimension were positively associated with progressive post-implant TR, which was associated with a trend toward HF hospitalization.
TR occurs mainly due to annular dilation and right ventricular enlargement, often secondary to LV dysfunction from myocardial or valvular causes, right ventricular volume and pressure overload, and cardiac chamber dilations 11. Lead-related TR is an underdetermined problem and may be caused by lead-related tricuspid leaflet injury or perforation or lead entanglement, impingement, or adherence to the tricuspid valve 6. However, lead-related tricuspid valve injury could not be fully detected and was only observed in 12% of patients with PPM-related severe TR by transthoracic echocardiography 6. Kim et al. reported that abnormal TR developed in 21.2%, worsened TR by ≥1 grade in 24.2%, and progressed to severe TR in 3.9% of patients with initially normal TR 4. However, Al-Bawardy et al. reported a small but significant increase in the prevalence of moderate and severe TR, both acutely and chronically after a cardiac device implantation5. Arabi et al. reported that TR was worsened by 1 grade in 70.8% and 2 grades in 17.1% of patients, and 19.5% of patients without baseline TR developed new-onset TR after the lead implantation in the follow-up period 12. In this study, the cumulative rate of progressive post-implant TR (increased TR grade of ≥2 degrees and/or TRPG of >30 mmHg) was from 1.3% in the first year to 18.4% in the sixth year. Moreover, higher pre-implant TRPG and larger post-implant LA dimension were independent predictors of progressive post-implant TR. Pacing-induced electrical and mechanical dyssynchrony of LV can also result in TR and MR13. However, in this study, pacing percentage and pacing QRS length was not associated with the development of progressive post-implant TR. In this study, larger post-implant LA size was an independent predictor of progressive post-implant TR. Our previous study showed that right and left atrial sizes were larger in patients with atrioventricular dyssynchrony after pacing 14. Atrial enlargement is a well known predictor of atrial fibrillation. Utsunomiya et al reported that functional TR with a structurally normal tricuspid valve may occur secondary to chronic atrial fibrillation and is associated with advanced age and right atrial enlargement15.
In one small retrospective cohort study, significant lead-induced TR was associated with a significantly increased incidence of all-cause mortality and HF events in patients after PPM implantation16. Other studies also reported post-implant TR to be an independent risk factor for late death 5, 13. However, a significant proportion of patients in previous studies included patients with HF and receiving ICD and cardiac resynchronization therapy (CRT). Patients with ICDs and/or CRT devices usually have poor LVEF and advanced HF and consequently, higher incident HF hospitalization and mortality. In our study, we only enrolled patients receiving PPM implantation and excluded patients receiving ICD or CRT and those with prior history of HF, valvular heart disease and preexisting abnormal (mild-moderate, moderate or severe) TR and abnormal (>30 mmHg) TRPG. In this large cohort study, progressive post-implant TR was significantly associated with HF hospitalization in univariate analysis and was associated with a non-significant trend toward HF hospitalization (p = 0.070) in multivariate analysis (Table 5), and progressive post-implant TR was not associated with cardiovascular and all-cause mortality. Therefore, patients with preserved LV function and without valve disease underwent transvenous ventricular-based pacemaker implantation should have baseline echocardiography evaluation before implant and those with higher pre-implant TRPG should have more vigorously echocardiographic follow-up for the development of progressive post-implant TR.