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Gian Luigi Nicolosi1

1 Department of Cardiology, ARC, Policlinic of San Giorgio, Italy

Abstract: Current Guidelines on Valvular heart Disease are suggesting different modalities of intervention only in pre-sence of severe valvular regurgitation. The precise classification of the severity of regurgitation by Echocardiography is then very crucial for clinical decision making. The recommendations for the assessment of valvular regurgitation are suggesting three different degrees of severity: mild, moderate and severe. However, in clinical practice, it is very common to find in the echocardiographic report intermediate degrees of severity, like „mild to moderate” or “moderate to severe” regurgitation. Some classification with four degrees of severity, including mild, moderate, moderate to severe and severe or massive are sometimes also used in clinical practice. Indetermination of severity can appear even more evident when another type of classification, as „at least moderate”, is used in the report. Greater effort should then be devoted in each echocardiographic examination to reach a sufficient confidence, through adequate imaging effort, trying to more clearly separate the three defined and standardized degrees of severity (mild, moderate, severe) in order to allow a better management of different clinical situations, avoiding unnecessary use of other multimodality imaging and potentially wrong operational decisions.

INTRODUCTION

Current Guidelines on Valvular heart Disease (VHD) are suggesting different modalities of intervention only in presence of severe valvular regurgitation1. The pre-cise classification of the severity of regurgitation by Echocardiography is then very crucial for clinical de-cision making. Valvular regurgitation or insufficiency is defined as the presence of backward or retrograde fl ow across a given closed cardiac valve2. It is evident that the spectrum of regurgitation severity should be considered as a continuum from the mildest trivial form of insuffi ciency to the maximal degrees of severe massive regurgitation. The great effort devoted to try to classify and separate the severity of regurgitation into three degrees (mild, moderate and severe) is a way to help the clinician to better manage the medical situation and the decision making process on how to proceed in the single patient. With the advent of Doppler techniques, it is frequent to detect some degree of regurgitation even in the absence of valve lesion. Trivial regurgitation in presence of a normal valve, particularly of the right-sided valves, should be then considered as physiologi-cal. In other situations, a complete echocardiographic assessment is more appropriate and should integrate quantification of the regurgitation, assessment of the valve anatomy and function, and the consequences of valvular disease on cardiac chambers2. Practically, the quantification of regurgitation is based on the integra-tion of a set of direct and indirect parameters. Direct criteria derive from colour Doppler Echocardiogra-phy2. Indirect criteria are mainly represented by the impact of regurgitation on the cardiac size and functi-on. In practice, the evaluation starts with two-dimensi-onal (2D) echocardiography, which can orient readily to a severe regurgitation in the presence of a major valvular defect or to a minor leak when the valve ana-tomy and leaflet motion are normal. Then, a careful assessment of the regurgitant jets by colour Doppler, using multiple views, can rapidly diagnose minimal re-gurgitation, which requires a priori no further quanti-fication. In the other cases, the use of a more quanti-tative method is advised when feasible. In the second step, the impact of the regurgitation on the ventricles, the atrium, and the pulmonary artery pressures are estimated2. Finally, the collected data are confronted with the individual clinical context and symptoms, in order to stratify the management and the follow-up. Of note, the comprehensive haemodynamic evaluati-on of patients with complex valve disease, including full quantitation of valvular regurgitation, should be performed by echocardiographers with advanced trai-ning level and appropriate exposure to valvular heart disease patients, according to the EAE recommenda-tions and including qualitative, semi-quantitative and quantitative parameters2.

HOW A STANDARDIZED METHODOLOGY CAN IMPACT ON CLINICAL PRACTICE

The recommendations for the assessment of valvu-lar regurgitation by Echocardiography are suggesting three different degrees of severity: mild, moderate and severe2-4. Since the introduction of 2-dimensional and Doppler echocardiography, even mild or trivial valvular regurgitation has become easily recognized and diagnosed non-invasively even in healthy normal individuals5-8. The prevalence rate of mitral regurgita-tion in normal subjects are increasing with age, while the prevalence rate of tricuspid and pulmonary re-gurgitation tends towards the lower rate in groups over the age of 30 years7,8. „Physiological” Mitral and Tricuspid regurgitation in normal valves are reported to occur more commonly in athletes than in control normal sedentary volunteers (mitral 69% vs 27%; tri-cuspid 76% vs 15%)9. Regurgitation of at least one of the cardiac valves was found in 91% of athletes, but in only 38% of control subjects (P <0.001)9. Multival-vular regurgitation should be considered as another characteristic of the “normal” athlete’s heart9. In VHD descriptive morphological findings of the valves, whi-ch always need to be well delineated in the echo re-port, and traditional calculated measurements have to be integrated into a concise and conclusive echo report10. Because VHD mainly affects geometry and function of cardiac cavities, the neighbouring cavities shall be accurately assessed with respect to size and function10,11. The precise classifi cation of the severity of regurgitation is then very crucial for clinical decisi-on making, even before considering clinical symptoms and the possible relation or compatibility of the same symptoms with the degree of regurgitation. The re-commendations for the assessment of valvular regur-gitation are suggesting three different degrees of se-verity: mild, moderate and severe2-4. However, in the heterogeneity of clinical practice, it is very common to find in the echocardiographic report intermediate degrees of severity, like “mild to moderate” or “mo-derate to severe” regurgitation. Indetermination of severity can appear even more evident when another type of classifi cation, as „at least moderate”, is used in the report. Diffi culties in grading severity of mitral regurgitation, considered as a continuum, are expec-ted and can derive from primary versus secondary MR, acute versus chronic regurgitation, holosystolic versus partial systolic MR, different loading conditi-ons, particularly blood pressure, and patient-related factors such body habitus or motion artifacts12,13. In cases where Tranthoracic Echocardiograhy (TTE) is technically diffi cult or it cannot deliver conclusive data, Transesophageal Echocardiography (TEE) and/ or Cardiac Computed Tomography (CCT), Cardiac Magnetic Resonance (CMR) or 3D Echocardiography could be useful12-15. Image quality can also be a limiting factor in assessing severity of chronic aortic regurgi-tation16. All these difficulties can be exalted by several technical and physiological factors such as inadequate acoustic windows, incomplete examinations, impinging jets, multivalvular diseases and heart failure17-19 How-ever, uncertainty does not help in clinical practice and decision making, and intermediate degree of severity should not be easily and immediately accepted as a rule or a way to spare time and effort and to conclude anyway a difficult echocardiographic examination. Re-search interventional clinical trials are supporting the need of precisely defi ned severity of regurgitation20,21 even though uncertainties and intermediate classifi – cation of severity have sometimes to be accepted20, but this should not be the general rule at a first glan-ce. Furthermore, progression of severity is generally slow, at least for aortic regurgitation22,23. This means that each new control follow-up examination gives a further opportunity to assess and grade more preci-sely the severity of regurgitation, in comparison with previous examination and report. This opportunity should be taken with awareness, great care and attention, following all the indications of guidelines1-4 and even a standardized methodology control, internal to each echocardiographic examination, for impro-ving confidence in reliably measuring left ventricular linear internal dimensions11. In fact, the assessment of severity of valvular regurgitation should be in some way logically separated and independent from the sub-sequent decision if the patient have to be operated on for that particular regurgitation. The interventional decision is in fact secondary not only to the fact that we assess the presence of severe regurgitation, but also in presence of a defined cut-off of ventricular di-latation and symptoms which can be ascribed to that specifi c observed VHD in that individual patient1. If in-dication to cardiac surgery and benefi t of surgery with reverse remodeling after the intervention, as assessed by Cardiac Magnetic Resonance (CMR), are conside-red as the reference gold standard for comparison in separating severe from moderate regurgitation, as assessed at the echocardiographic examination24,25, this modality of approach can introduce further bias. The difficulty of having and applying an easy and direct access to CMR, is further underlined by the compari-son of reproducibility and consistency of conventional Magnetic Resonance Imaging (MRI) with 4D flow MRI in the quantification of Mitral and Tricuspid Regurgi-tation26. The paper is in fact dealing with only 21 ca-ses recruited in a period of time of 21 months26. This approach does not seem then a general solution for quantifying valvular regurgitation. In daily clinical prac-tice we can in fact decide that a patient has severe regurgitation by Echocardiography, but does not need surgery at present and we can follow-up strictly his LV size by subsequent examinations, until linear LV inter-nal dimensional cut-off defined by the guidelines are reached 1 and the decision to intervene can appropri-ately be made. Multimodality imaging should be then considered only as a complementary second step, when Echocar-diography, first step technique more easily accessible and repeatable in clinical practice, is giving equivocal or uncertain result and a clinical decision is immediately needed in that single patient12-16,25. It is also important to say that current European guidelines for the ma-nagement of valvular heart disease (1) are preferring echocardiographic linear LV size internal dimensional cut off for the decision to undergo surgery, proba-bly due also to the greater variability and uncertainty of volume measurements in clinical practice. In fact the accuracy of assessing linear internal dimensions of LV size can undergo further control during the same echocardiographic examination, since they can be assessed from different echocardiographic windows (parasternal, apical and subcostal) allowing a simpli-fied three-dimensional spatial approach for improving confi dence in reliably measuring such left ventricular linear internal dimensions11. The development of a consensus algorithm by ex-perts has also allowed improvement of interobserver agreement and accuracy, at least in the determination of Tricuspid Regurgitation severity27. Accreditation of echocardiographic laboratories could further help to reach more complete reporting and better image quality28. In this setting echocardiographic quantifica-tion and color Doppler image quality were associated with improved concordance in grading valvular heart disease28. Future quality improvement initiatives sho-uld highlight the importance of high-quality color Doppler imaging and echocardiographic quantificati-on to improve accuracy, reproducibility, and quality of echocardiographic studies for valvular heart disea-se28.

CONCLUSIONS

Greater effort should be devoted, in each echocardi-ographic examination, to try to more clearly separate the three defi ned degrees of severity (mild, moderate, severe), following all the indications of published gui-delines, in order to allow a better management of di-fferent clinical situations and to avoid unnecessary or inappropriate use of other multimodality imaging and potentially wrong operational decisions. Intermediate and uncertain classification should be avoided as much as possible, or only very exceptionally accepted in the clinical arena, after long, comprehensive and adequate evaluation of the complete echocardiographic exami-nation. The use of other multimodality imaging tech-niques could be occasionally helpful in such situations, while an easy and immediate access to multimodality imaging should not be considered as an abjuration to a complete and comprehensive echocardiographic study. Furthermore, we have to take into account the easy repeatibility of echocardiographic examinations. Serial short term follow-up echocardiographic studies could be in fact programmed in these uncertain situ-ations, in order to make any effort to reassess valve morphology and function, to grade again regurgitation severity by Doppler, to reassess chamber dimensions and function, all in comparison with previous exami-nation and reports, in the frame of clinical symptoms. This aware try again could possibly overcome, in the next examination, those uncertainties and difficulties, allowing to achieve a more strict adherence to the recommended classification into three degrees of se-verity of regurgitation, i.e. mild, moderate and severe.

Conflict of interest: none declared.

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