Right-sided heart failure, right ventricular dysfunction, and tricuspid insufficiency (TI) have become focal points in recent structural heart disease treatment studies, both percutaneous and surgical. Previous blog posts analyzing key studies affirm this trend. These three entities, while often occurring together, are complementary and can present independently. In line with this, the authors propose diverse clinical scenarios, likely to inspire future right heart failure classifications, as seen with left heart failure. Initially, they outline a scenario involving patients with preserved right ventricular function, where congestive symptoms may be absent or mild (fully reversible) or, alternatively, more pronounced congestion may be present (potentially reversible condition). At the other end of the spectrum, there are patients with right ventricular dysfunction, again either with mild (potentially reversible) or severe (end-stage heart disease) congestion.

The reversibility of right-sided heart failure largely depends on the efficacy of medical treatment and TI correction, whether achieved through depletive therapy and/or invasive techniques. Due to the unique nature of the tricuspid valve, its insufficiency follows distinct pathophysiology and mechanisms that, in my view, align well with Carpentier’s classification without necessitating additional classifications, which are also imperfect. Notably, Shah modified this classification to include mechanisms of mitral insufficiency, such as anterior systolic motion, while El Khoury adapted it to classify mechanisms of aortic insufficiency. For TI, the mechanisms are as follows:

• Isolated: corresponding to Carpentier type I mechanism due to annular dilation without excessive or restricted movement, typically caused by atrial dilation from atrial fibrillation (AF) or persistent intracardiac shunts.
• Primary: aligned with Carpentier types I (perforation of various etiologies, whether traumatic or endocarditic), type II (excessive movement causing prolapse or flail from congenital, traumatic causes, or complications from endomyocardial biopsy or pacemaker lead extraction), and type IIIA (commonly rheumatic disease, congenital, or movement restriction from pacemaker leads).
• Secondary: linked to type IIIB mechanism, involving systolic restriction from right ventricular dysfunction without intrinsic valve disease but often associated with Carpentier type I mechanism due to annular dilation under right-sided volume overload.

Cleveland Clinic reports on their experience with tricuspid valve surgery in patient subgroups mentioned above, characterized by potentially reversible right-sided heart failure: either with concomitant right ventricular dysfunction and mild congestion or without right ventricular dysfunction but severe congestion. Over seven years, they gathered data on 62 patients undergoing isolated tricuspid surgery (excluding infective endocarditis; 73% had prior valve surgery, 19 with previous tricuspid valve procedures; 45% in preoperative AF; 16 with trans-tricuspid pacemaker leads). Initially, the small sample size stands out, as even a high-volume center like Cleveland Clinic operated on fewer than nine patients per year. Moreover, congenital patients were not included, nor was the rejection rate disclosed before selecting these 62 patients.

A crucial aspect in understanding this study is the dichotomy of TI into “functional” or “structural” categories. The first comprises the mechanisms described for “isolated” and “secondary,” while the second entirely covers the “primary” category.

The authors conducted a thorough systematic collection of clinical and echocardiographic variables and performed multidimensional statistical analysis, combining various clinical, echographic, and hemodynamic variables grouped into clusters. Despite the sophistication of this approach (evidencing the influence of EH Blackstone), the authors acknowledge that some analyses may have been compromised due to the limited sample size. Key findings are summarized below:

1. Upon comparing the two forms of tricuspid insufficiency, significant demographic, clinical, hemodynamic, and morphological differences in right ventricular function were observed. Patients with functional TI were generally older, had greater right atrial dilation, and higher MELD-sodium scores. Clinically, they exhibited higher degrees of jugular venous congestion, dependent edema, and elevated right and pulmonary artery pressures. Echocardiographically, they showed greater annular dilation with lower TAPSE values; however, other parameters for right ventricular function (fractional area change, ejection fraction, right ventricular systolic and diastolic pressures, systolic excursion velocity, free wall strain) and ventricular diameters did not differ between TI etiologies. These findings indicate a prevalence of “secondary” etiology over “isolated” in the cohort with “functional” TI.
2. Independent of the tricuspid valve etiology, right-sided heart failure severity was better characterized by morphological parameters (primarily volume) than functional metrics. In their discussion, the authors highlight that the International Right Heart Foundation Working Group considers ventricular dilation as the earliest marker of right ventricular failure over function parameters. This association with higher AF rates and congestion symptoms (ascites, edema) further supports this point. Despite these patients exhibiting advanced coagulopathy, post-surgical recovery was comparable to those without dilation or significant congestion.
3. Postoperative outcomes were similarly favorable for both etiologies, with a 0% hospital mortality rate in the “structural” group and 3.2% in the “functional” group. Prosthetic replacement was more common in “structural” cases (55%), whereas repair was predominant in “functional” cases (84%). Postoperative morbidity was similar across groups, though the “functional” group required more blood transfusions and experienced longer hospital stays. Long-term survival over eight years was notably poorer in the “functional” group, a trend that persisted even after propensity matching the two cohorts.

The authors conclude that the cluster analysis of right-sided heart failure characteristics in patients undergoing isolated tricuspid valve surgery identifies two distinct patient profiles. Despite excellent immediate postoperative outcomes, they suggest expanding treatment indications to include earlier-stage patients, particularly those with functional etiology and right ventricular dysfunction/dilation.

COMMENTARY:

This study serves as a renewed call for early intervention in TI, challenging the misconception of its benign nature. Previous blog posts support this stance, with this study providing further evidence.

Simultaneous intervention with other procedures, particularly left-sided valvular or congenital heart disease in adults, should be a standard in patients with right ventricular and tricuspid annular dilation, even in the absence of significant insufficiency. Additionally, the referral of patients with isolated disease for invasive therapies may become more common in coming years. Treatment indications should be based on risk, outcomes, and the corrective potential of the two main approaches: surgery (with its extensive technical options) and edge-to-edge therapy (TriClip® and Pascal®), pending further experience with other devices and prototypes in development for annuloplasty (Millipede®, Cardioband®, DaVingi®, TriCinch®) and percutaneous prostheses (TricValve®, TriCentro®, etc.).

For timely intervention, it will be essential to redefine parameters for evaluating right ventricular function, as dilation alone is a more sensitive prognostic marker than current measures of dysfunction. Right ventricular physiology may differ substantially from that of the left ventricle, suggesting that diagnostic parameters applied to the left may not fully apply to the right. Continued evidence aggregation will advance our understanding of right ventricular mechanics, potentially leading to its consideration as a unique entity rather than merely a weaker counterpart to the left ventricle.

Regarding TI, Carpentier type IIIB mechanisms, “secondary” or “functional” etiology, stand out for their especially poor prognosis, where early intervention—even in a preclinical phase—may improve outcomes. The findings clearly indicate that symptom-based correction, while beneficial, results in lower survival rates compared to patients with “organic” or “primary” etiologies.

In summary, this evidence-generating study sheds light on the timing of intervention. Though questions remain on the choice of repair versus replacement and the appropriate specialist (in a simplified, pessimistic view, and one hopefully inaccurate, the dichotomy between surgery/surgeon versus interventional cardiologist). The era of tricuspid valve intervention has only just begun.

REFERENCE:

Elgharably H, Ibrahim A, Rosinski B, Thuita L, Blackstone EH, Collier PH, et al. Right heart failure and patient selection for isolated tricuspid valve surgery. J Thorac Cardiovasc Surg. 2023 Sep;166(3):740-751.e8. doi: 10.1016/j.jtcvs.2021.10.059