Severe mitral regurgitation due to right ventricular apical pacing

Perspectives on Secondary Mitral Regurgitation in Heart Failure

PURPOSE OF THE REVIEW

This review focuses on broader perspectives of mitral regurgitation (MR) in patients with heart failure.

RECENT FINDINGS

The ratio of regurgitant volume to end-diastolic volume appears to help identify patients who may benefit from valve interventions. Secondary MR is not only attributed to geometric changes of the LV but also related to the structural changes in the mitral valve that include fibrosis of the mitral leaflets and changes in the extracellular matrix. The transition from mild to severe secondary MR can occur at different rates, from a slow LV remodeling process to a more abrupt process precipitated by an inciting event such as atrial fibrillation. Septal flash and apical rocking, two new visual markers of LV mechanical dyssynchrony, appear to be predictive of MR reduction following cardiac resynchronization therapy. Optimal guideline-directed medical therapy has been shown to decrease the severity of secondary MR effectively. A theoretical framework to characterize secondary MR as it relates to the onset of MR is proposed. Type A: Early onset of MR contemporaneous with myocardial injury. The maladaptive LV remodeling occurs in parallel with MR. Type B: LV remodeling proceeds without significant MR until the LV is moderately dilated, which coincides with or without inciting factors such as atrial fibrillation. Type C: LV remodeling proceeds after myocardial injury without significant MR until the LV is severely dilated. MR is a late manifestation of LV remodeling.

Treatment of Functional Mitral Regurgitation in Heart Failure

PURPOSE OF REVIEW

To analyze the current state of the art of functional mitral regurgitation (FMR) treatment.

RECENT FINDINGS

The first-line treatment of severe FMR consists of guideline medical therapy (GMT) and resynchronization therapy when indicated; the impact of new medical therapies like sacubitril/valsartan needs further assessment. Valvular intervention may be considered in FMR symptomatic patients despite GMT, and can be performed surgically or percutaneously. MitraClip is a safe percutaneous procedure associated with symptoms improvement. Recently, the COAPT trial showed superior outcomes for MitraClip versus GMT contrasting the MITRA-FR trial which showed no benefit of MitraClip compared with GMT. These results should be interpreted as complementary rather than opposite. The COAPT trial provided a "proof of concept" that percutaneous treatment of severe FMR in patients without too advanced left ventricular disease translates into a prognostic benefit. Careful patient selection will play a critical role in defining the clinical niche for successful interventions.

Ventricular pacing - Electromechanical consequences and valvular function

Although great strides have been made in the areas of ventricular pacing, it is still appreciated that dyssynchrony can be malignant, and that appropriately placed pacing leads may ameliorate mechanical dyssynchrony. However, the unknowns at present include: 1. The mechanisms by which ventricular pacing itself can induce dyssynchrony; 2. Whether or not various pacing locations can decrease the deleterious effects caused by ventricular pacing; 3. The impact of novel methods of pacing, such as atrioventricular septal, lead-less, and far-field surface stimulation; 4. The utility of ECG and echocardiography in predicting response to therapy and/or development of dyssynchrony in the setting of cardiac resynchronization therapy (CRT) lead placement; 5. The impact of ventricular pacing-induced dyssynchrony on valvular function, and how lead position correlates to potential improvement. This review examines the existing literature to put these issues into context, to provide a basis for understanding how electrical, mechanical, and functional aspects of the heart can be distorted with ventricular pacing. We highlight the central role of the mitral valve and its function as it relates to pacing strategies, especially in the setting of CRT. We also provide future directions for improved pacing modalities via alternative pacing sites and speculate over mechanisms on how lead position may affect the critical function of the mitral valve and thus overall efficacy of CRT.

An approach to the stepwise management of severe mitral regurgitation with optimal cardiac pacemaker function

Right ventricular apical pacing may cause or worsen mitral regurgitation (MR). Potential mechanisms for this adverse sequelae include intraventricular dyssynchrony, altered papillary muscle function, pacing-induced cardiomyopathy with left ventricular dilation, and annular dilation. In contrast, biventricular (BiV) pacing may improve MR presumably by opposing the negative effects. Whether or not left ventricular lead location is important in treating mitral regurgitation in patients with pacemakers is unknown.

We report a case of severe MR and left ventricular (LV) systolic failure in a patient with right ventricular pacing. Multiple potential etiologies for the worsening valve function were noted, and a stepwise iterative optimizing scheme that included basal lateral LV pacing improved mitral valve function and ameliorated heart failure symptoms.