Eclipsed MI: how to treat this paroxysmal mitral insufficiency?

Mitral regurgitation eclipsed: a paroxysmal entity with critical diagnostic challenges

"Eclipsed" mitral regurgitation (MR) is a rare and paroxysmal form of functional MR occurring despite a preserved left ventricular ejection fraction. This case report details the journey of an 82-year-old female patient, suffering from systemic scleroderma and atrial fibrillation, admitted four times in six months for acute heart failure. The major clinical challenge lies in the fleeting nature of the regurgitation: massive during episodes with a total loss of leaflet coaptation, it becomes minimal between crises, making provocative tests (notably with norepinephrine) often inconclusive.

The objective of this study is to characterize the distinctive echocardiographic signs of eclipsed MR — such as the "dagger-shaped" jet and reversible pulmonary hypertension — in order to better understand this underdiagnosed pathology. The authors test the hypothesis that this pathology constitutes a unique pathophysiological entity, distinct from chronic atrial or ventricular functional MR. The use of mitral valve replacement (MVR) is analyzed here as a necessary response to recurrent episodes of pulmonary edema, with histopathological analysis confirming the absence of significant intrinsic structural lesions despite the clinical severity of the episodes.

Methodology of clinical investigation

This clinical case dissects the management of an 82-year-old female patient with systemic sclerosis, admitted four times for acute heart failure within six months. The methodological challenge lies in the echocardiographic capture of a dynamic and fleeting phenomenon: "eclipsed" mitral regurgitation (MR).

The team deployed a specific diagnostic arsenal to characterize this massive but reversible regurgitation:

• Comparative transthoracic echocardiography (TTE): the authors performed real-time examinations during paroxysmal episodes of dyspnea, systematically comparing them with data obtained during phases of clinical stability (where MI remained mild).
• Pharmacological provocation test: to attempt to reproduce the loss of valvular coaptation observed in the emergency setting, a norepinephrine infusion was administered in stages, reaching a dose of 0.1 μg/kg/min under continuous hemodynamic and ultrasound monitoring.
• Monitoring and differential diagnosis: telemetric monitoring was maintained throughout the hospitalization to evaluate a possible arrhythmic origin. The valvular apparatus was also the subject of additional exploration by transesophageal echocardiography (TEE).
• Surgical and tissue validation: given the recurrence of crises despite optimal medical therapy, urgent mitral valve replacement associated with tricuspid annuloplasty was performed. The methodology includes intraoperative macroscopic inspection of the leaflets, chordae, and pillars, followed by histopathological analysis of the mitral leaflet and papillary muscle aimed at characterizing the structural damage to the valvular tissue.

Echocardiographic dynamics and hemodynamic instability

The key observation in this case lies in the paroxysmal and massive nature of the mitral regurgitation (MR). During the acute episode documented in the emergency department, transthoracic echocardiography (TTE) revealed a total loss of coaptation between the anterior and posterior leaflets, resulting in massive MR. A major clinical finding: this regurgitation was accompanied by a drop in systolic blood pressure, from 130 mmHg to 100 mmHg.

Doppler analysis revealed a "dagger-shaped" MR jet, characterized by an early peak followed by rapid deceleration. Simultaneously, pulmonary pressures showed a dramatic fluctuation correlated with symptoms:

Note that norepinephrine provocation tests (up to 0.1 μg/kg/min) failed to reproduce leaflet malcoaptation, confirming the diagnostic difficulty of "eclipsed" MR outside of spontaneous episodes.

Intraoperative findings and histopathology

The surgical intervention (mitral valve replacement and tricuspid annuloplasty) allowed for direct inspection of the valvular apparatus. Contrary to expectations given such severe MI, structural lesions were minimal:

• Macro-anatomy: Only a slight thickening of the anterior leaflet was observed. There was no chordal rupture, nor elongation or shortening of the papillary muscles. The mitral annulus showed no significant dilation.
• Histopathology: Tissue examination confirmed the absence of major intrinsic damage. The results show a preserved valvular architecture, with only mild fibrosis and myxoid changes. No inflammatory infiltration or amyloid deposits were detected.

These results highlight that eclipsed MR is based on an acute and reversible functional mechanism, independent of organic valve degradation or chronic ventricular remodeling.

Clinical analysis and diagnostic limitations of eclipsed MI

This clinical case highlights the fleeting and potentially fatal nature of eclipsed mitral regurgitation (MR). Acute phase echocardiographic capture revealed a massive loss of leaflet coaptation and a dagger-shaped Doppler jet, indicating severe and paroxysmal MR that was completely absent during routine examinations. The most striking aspect is the discrepancy between clinical severity and operative findings: direct inspection and histopathology showed only minor alterations (mild fibrosis, myxoid degeneration), confirming that this is a dynamic functional entity rather than an organic one.

A major limitation identified in this study is the inefficiency of standard provocation tests. Despite a norepinephrine infusion of up to 0.1 μg/kg/min, massive MR could not be artificially reproduced, highlighting that diagnosis relies almost exclusively on bedside imaging during a spontaneous crisis. Although the study suggests a clear distinction from atrial functional mitral regurgitation (AFMR) due to the absence of significant annular dilation, the exact triggering mechanism remains undetermined in this 82-year-old patient suffering from scleroderma.

Implications for practice

The success of mitral valve replacement (MVR) in this case shows that surgery can be curative in preventing recurrences of acute pulmonary edema, even in very elderly patients. The surgical decision was driven by the failure of medical treatment and the immediate life-threatening risk during repeated crises.

Study essentials

This clinical case documents an "eclipsed" mitral regurgitation (MR) in an 82-year-old patient: a massive paroxysmal regurgitation with loss of coaptation and a "dagger-shaped" jet, occurring despite a preserved ejection fraction. The diagnosis was based on echocardiography at the peak of a crisis (tricuspid regurgitation gradient at 57 mmHg), as inter-critical examinations and provocation tests remained negative.

In concrete terms, for the practitioner:

• Synchronous imaging: A normal result outside of an attack does not rule out the diagnosis; Doppler ultrasound must imperatively be performed during the acute phase to capture the transient malcoaptation.
• Clinical profile: Consider this entity in cases of unexplained recurrent acute pulmonary oedema (APO), particularly if the valvular apparatus appears structurally sound at rest.
• Surgical option: In cases of recurrence despite optimal medical treatment, mitral valve replacement prevents crises definitively, even without prior annular dilation or chronic organic lesions.

Technical lexicon of the study

Eclipsed mitral regurgitation: A rare paroxysmal entity characterized by massive and reversible functional mitral regurgitation in patients with preserved left ventricular ejection fraction (LVEF). The severity of the leak is demonstrable only during acute clinical episodes.

Malcoaptation of the leaflets: Transient loss of contact between the anterior and posterior mitral leaflets, identified by transthoracic echocardiography (TTE) as the causal mechanism of massive regurgitation during the acute episode.

Dagger-shaped jet: Continuous wave Doppler flow profile showing an abrupt protosystolic peak followed by rapid deceleration, characteristic of the hemodynamic regurgitation profile during an eclipsed MR crisis.

Myxoid degeneration: Histopathological alteration revealed by Alcian blue staining, characterized by an accumulation of acid mucopolysaccharides and an expansion of the spongiosa layer of the mitral leaflet, without associated major organic lesion.

Norepinephrine stress echocardiography: Pharmacological provocation protocol (using an infusion of up to 0.1 μg/kg/min) designed to reproduce leaflet malcoaptation by increasing afterload; the study specifies that a negative test does not exclude the diagnosis.

TR-PG (Tricuspid Regurgitation Pressure Gradient): Tricuspid regurgitation pressure gradient used to monitor paroxysmal pulmonary hypertension, increasing from 21 mmHg at rest to 57 mmHg during the acute episode in this specific case.

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