Hector I. Michelena

Clinical Context and Mechanism of Functional Tricuspid Regurgitation in Patients With and Without Pulmonary Hypertension

Background— Functional tricuspid regurgitation (FTR) with structurally normal valve is of poorly defined mechanisms. Prevalence and clinical context of idiopathic FTR (Id-FTR) (without overt TR cause) are unknown. Methods and Results— To investigate prevalence, clinical context, and mechanisms specific to FTR types, Id-FTR versus pulmonary hypertension-related (PHTN-FTR, systolic pulmonary pressure ≥50 mm Hg), we analyzed 1161 patients with prospectively quantified TR. Id-FTR (prevalence 12%) was associated with aging and atrial fibrillation. For mechanistic purposes, we measured valvular and right ventricular (RV) remodeling in 141 Id-FTR matched to 140 PHTN-FTR and to 99 controls with trivial TR for age, sex, atrial fibrillation, and ejection fraction. PHTN-FTR and Id-FTR were also matched for TR effective-regurgitant-orifice (ERO). Id-FTR valvular alterations (versus controls) were largest annular area (3.53±0.6 versus 2.74±0.4 cm2, P<0.0001) and lowest valvular/annular coverage ratio (1.06±0.1 versus 1.45±0.2, P<0.0001) but normal valve tenting height. PHTN-FTR had mild annular enlargement but excessive valve tenting height (0.8±0.3 versus 0.35±0.1 cm, P<0.0001). Valvular changes were linked to specific RV changes, largest basal dilatation, and normal length (RV conical deformation) in Id-FTR versus longest RV with elliptical/spherical deformation in PHTN-FTR. With increasing FTR severity (ERO ≥40 mm2), changes specific to each FTR type were accentuated, and RV function (index of myocardial performance) was consistently reduced. Conclusions— Id-FTR is frequent, linked to aging and atrial fibrillation, can be severe, and is of unique mechanism. In Id-FTR, excess annular and RV-basal enlargement exhausts valvular/annular coverage reserve, and RV conical deformation does not cause notable valvular tenting. Conversely, PHTN-FTR is determined by valvular tethering with tenting linked to RV elongation and elliptical/spherical deformation. These specific FTR-mechanisms may be important in considering surgical correction in FTR.

Progress in the Treatment of Severe Mitral Regurgitation

Organic mitral regurgitation (MR) is prevalent in the general population. Disease progression, involving potentially irreversible left ventricular dysfunction, implies a poor prognosis for patients who do not receive appropriate treatment. Immediate rescue surgery is indicated in those with severe MR in whom subclinical left ventricular dysfunction is suggested by echocardiographic measurements or the presence of symptoms, however minor. Patients whose symptomatology is unclear should be evaluated by exercise testing. Not all forms of severe organic MR are the same: the presence of risk factors in patients with severe asymptomatic MR and preserved ventricular function indicates a suboptimal prognosis over the medium-to-long term and should prompt early mitral repair if there is a low surgical risk and the probability of a successful repair is >90-95%. The patient should be referred to a specialized surgical center if necessary. Appropriate training of surgeons in mitral repair is essential. Ischemic MR carries a worse prognosis and the risk of surgery is higher. Consequently, treatment decisions must be patient-specific and take into account the possibility of repair, the risk of surgery, and the need for concomitant surgical revascularization. New percutaneous approaches to mitral repair are being developed for selected patient groups.

Avances en el tratamiento de la insuficiencia mitral grave

La insuficiencia mitral (IM) organica es prevalente en la poblacion. Su progresion, con deterioro potencialmente irreversible de la funcion ventricular izquierda, pone de manifiesto el grave pronostico de los pacientes que no reciben tratamiento oportunamente. La deteccion de disfuncion subclinica del ventriculo izquierdo a traves de parametros ecocardiograficos o la presencia de sintomas, asi sean minimos, indican cirugia de rescate inmediata en la IM grave. Los pacientes con sintomatologia incierta deben ser evaluados con prueba de esfuerzo. No todas las IM organicas graves son iguales: la presencia de factores de riesgo en la IM grave asintomatica con funcion ventricular normal indica peor pronostico a medio y largo plazo, lo cual debe estimular la cirugia temprana con reparacion si el riesgo quirurgico es bajo y la posibilidad de reparacion es > 90-95%. Si es necesario, se debe referir al paciente a centros especializados. El entrenamiento adecuado de cirujanos en la reparacion mitral es critico. La IM isquemica acarrea un peor pronostico, con mayor riesgo quirurgico, y las decisiones sobre el tratamiento deben ser especificas para cada paciente, teniendo en cuenta la posibilidad de reparacion, el riesgo quirurgico y la necesidad de revascularizacion quirurgica concomitante. Se esta estudiando nuevos procedimientos percutaneos para pacientes seleccionados.