Clinical relevance of tricuspid regurgitation in right ventricular pacing and left heart disease

Abstract

Valvular heart disease is a relatively common type of heart disease found globally. Tricuspid regurgitation (TR) is a widespread concomitant consequence of valvular disease, especially in patients with left-sided heart valve disease. Tricuspid regurgitation caused by the right ventricle (RV) pacing has also received much attention in recent years. Massive and long-term existing TR among patients with heart failure may affect their prognosis as it causes chronic congestion and subsequent hepatorenal dysfunction. Tricuspid annuloplasty (TA) is currently the primary treatment for significant TR. To date, however, the deep mechanism of RV pacing-induced TR is unclear, and how to improve and prevent TR and extend long-term survival in double valve replacement (DVR) patients has not been well established. Therefore, the present thesis aims to assess the prevalence and management of TR in RV pacing and DVR patients. Chapter 2 describes a prospective study of RV pacemaker lead-induced TR between right ventricular apex (RVA) pacing and non-right ventricular apex (non-RVA) pacing under the three-dimensional echocardiography (3DE). Echocardiography provides a crucial diagnosis method. A total of 284 patients were evaluated for the change of TR severity following permanent pacemaker implantation. Results showed that RVA pacing is associated with worsening of TR severity compared with non-RVA pacing (55.3% vs 44.7%, p = 0.01). RVA pacing was more likely to impinge the posterior leaflet, whereas non-RVA pacing was more likely to be positioned in the middle without the interference of any tricuspid valves (TVs). Under 3DE, Chapter 2 demonstrates that preferential lead impingement to the tricuspid valves may be one possible mechanism that could explain the higher frequency of TR in RVA pacing than in non-RVA pacing. Chapter 3 evaluates the clinical prognostic value of two modified Model for End-stage Liver Disease (MELD) scores in 210 patients undergoing DVR surgery. Severe and chronic TR causes hepatic and renal dysfunction, and the modified MELD scores reflect the hepatorenal function. In clinical settings, the Model for End-stage Liver Disease eXcluding International normalised ratio (INR) (MELD-XI) scores and modified MELD scores with albumin replacing the international normalised ratio (MELD-Albumin) scores have been reported as predictors of adverse events in liver and heart diseases. In contrast, their predictive function in DVR patients has received less attention. Chapter 3 assessed the clinical prognostic value of modified MELD scores in DVR patients. The results showed that DVR-only patients have a higher risk of worsening TR than those receiving DVR combined TA and that significant preoperative TR was associated with 1-year adverse outcomes. Secondly, the MELD-XI and MELD-Albumin scores independently predicted adverse outcomes during the follow-up. Lastly, the MELD-Albumin scores provided incremental prognostic value to clinical parameters and the EuroSCORE II (net reclassification index = 0.34; p < 0.01). This outcome demonstrates that monitoring the modified MELD scores before surgery may provide helpful information for risk-stratification in DVR patients. In conclusion, this thesis systematically evaluates the different RV pacing sites of lead-induced TR and monitor the modified MELD scores to stratify the risk before surgery in DVR patients.