Author + information
- Received December 30, 2015
- Accepted February 2, 2016
- Published online May 17, 2016.
- aDivision of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
- bDepartment of Cardiology, Mount Sinai Beth Israel Hospital, New York, New York
- ↵∗Reprint requests and correspondence:
Dr. Rick A. Nishimura, Division of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905.
The 2014 American College of Cardiology/American Heart Association guidelines for valvular heart disease were released to help guide the clinician in caring for patients with this ever more prevalent and complex group of diseases and have been instrumental in providing a foundation of knowledge for the management of patients with valvular heart disease. However, there are many caveats in applying the guidelines to individual patients. As clinicians, we wish to outline important aspects to be considered by other clinicians, including the integration of the echocardiogram with the history and physical examination, recognition of discordant data within an echocardiographic examination, and proper interpretation of the cutoff measurements applied to timing of intervention. Decisions regarding management should be individualized to the institution, particularly when recommending early operation for an asymptomatic patient. Finally, all decisions should be individualized to each patient by not only recognizing specific comorbidities, but also understanding the patient’s needs and preferences.
Due to the aging of the population, the last 50 years have brought to medical practice an increasing number of patients presenting with age-related or degenerative valvular heart disease (1). Thus, the knowledge and skills in the diagnosis and treatment of valvular heart disease have become a progressively more important part of the core competencies of all cardiologists. In parallel, the diagnosis and management of patients with valvular heart disease have undergone a significant transformation since the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for the management of patients with valvular heart disease were first written in 1998 (2). There are now long-term data on the natural history of patients with the different valve diseases using objective measures of valve severity at baseline. The development of modern cardiovascular imaging modalities—such as 2-dimensional, Doppler, transesophageal, and 3-dimensional echocardiography; computed tomography (CT); and cardiac magnetic resonance (CMR)—has significantly enhanced the clinician’s armamentarium for diagnosis and quantitation of valve severity. Continuous improvement in interventions for patients with valvular heart disease, including the refinement of valve repair and the development of newer-generation prostheses, has led to a lowered threshold for indications for valve intervention. In addition, less invasive interventions, such as transcatheter valve replacements and repair, have extended the population who can receive valve interventions to elderly, frail patients. On the basis of this accumulating knowledge, a new version of the ACC/AHA guidelines for the management of patients with valvular heart disease was released in 2014 to help guide the clinician in caring for patients with this ever more prevalent and complex group of diseases (3). The Valvular Heart Disease Guidelines Committee was composed of experts in all areas of cardiovascular practice involving patients with valvular lesions, including clinicians, imagers, interventionalists, surgeons, and anesthesiologists. Much time and effort was put into creating class recommendations on the basis of evidence as well as the clinical experience of experts in valvular heart disease (4). However, because no guideline can be written to account for the richness of biological variability in our patients, there are many caveats in applying the results of these guidelines to patient care. We truly feel that a clinician who follows the recommendations of the guidelines 100% of the time is not properly doing his or her job as a physician. This paper outlines a clinical perspective for interpreting and implementing these guideline recommendations to provide optimal patient care.
Integration of the Echocardiogram with the History and Physical Examination
Echocardiography has rapidly evolved as the most important single diagnostic modality for patients with valvular heart disease. Two-dimensional echocardiography is able to visualize valve morphology and motion, provide concomitant information about the status of the left ventricle and other cardiac chambers, as well as evaluate other cardiac structures, such as aortic size and pericardial abnormalities. Doppler echocardiography now provides hemodynamic information regarding the severity of valve stenosis, valve regurgitation, and intracardiac and pulmonary pressures (5). However, the echocardiogram (or any other test) should not be used alone in clinical decision making for patients with valvular heart disease because no cardiac test is both 100% sensitive and 100% specific. A meticulous history and physical examination is of great importance in the evaluation of patients with valvular heart disease, for it establishes a “pre-test probability” of the severity of a valve lesion and its effect on the circulation and cardiac chambers. The results of a 2-dimensional and Doppler echocardiogram are most useful when applied as a diagnostic modality using the pre-test probability as a baseline. In patients with suspected coronary artery disease, the accuracy of a stress test is dependent upon the pre-test probability of coronary artery disease in the patient being studied. The same concept then applies to the diagnostic utility of an echocardiogram for patients with valvular heart disease (Central Illustration).
For instance, a patient may present with exertional symptoms of dyspnea and clinical findings of severe aortic stenosis, with a dampened carotid upstroke, a late-peaking systolic ejection murmur, and absent aortic component of the S2. The Doppler echocardiogram might show a mild degree of aortic stenosis with a mean gradient <30 mm Hg and a valve area >1.2 cm2. In this instance, the echocardiogram may have significantly underestimated the severity of aortic stenosis due to the inability of the echocardiographer to properly align the Doppler beam with the aortic velocity jet. The high pre-test probability from physical examination that the patient has severe aortic stenosis should cause the clinician to doubt the echocardiographic results, leading to additional investigation.
Another not uncommon example of the need for using the physical examination is the patient presenting with new-onset dyspnea in whom a loud holosystolic murmur and an early diastolic filling sound are heard at the apex. The echocardiogram may show a very narrow eccentric jet of mitral regurgitation that occupies <15% of the left atrial area, interpreted as a mild degree of mitral regurgitation. However, the history and physical examination suggest severe mitral regurgitation due to an unsupported segment of the posterior leaflet. If an echocardiographer relies only on regurgitant jet area for determination of mitral regurgitation severity, there will be a gross underestimation of the severity of regurgitation due to the loss of energy of the color flow jet as it impinges on the atrial wall.
The clinician also has to be aware of discrepancies contained within the echocardiographic report. A report may describe severe mitral regurgitation due to mitral valve prolapse on the basis of the calculation of a large effective orifice area of 0.4 cm2 and a central jet of mitral regurgitation that occupies nearly two-thirds of the left atrial area in a patient with mitral valve prolapse. However, there may be normal left atrial and ventricular volumes. If the left ventricular and left atrial sizes are normal in an asymptomatic patient, severe chronic mitral regurgitation cannot be present. If 50% of left ventricular stroke volume is regurgitated into the left atrium, diastolic pressure has to be elevated and forward output has to be diminished, conditions that cause symptoms. In this case, the severity of mitral regurgitation is overestimated by using the proximal isovelocity surface area, which assumes that the regurgitation occurs throughout all of systole, whereas, in some patients with mitral valve prolapse, the regurgitation occurs in only very late systole (6). The physical examination would demonstrate a very late soft systolic murmur with no diastolic filling sound and clear lungs, all consistent with only mild-to-moderate mitral regurgitation.
It is necessary for the clinicians to directly review the actual echocardiographic images, rather than rely only on text or numbers from a report. The proper interpretation of an echocardiogram should be an essential competency of all cardiologists in practice. Additional knowledge should be sought from experts in this field, if indicated. Clinicians must be aware of the possible discrepancies that occur in the interpretation of echocardiographic findings in patients with valvular heart disease (Table 1). There are also unique hemodynamic challenges that arise from Doppler echocardiographic studies in these patients that must be recognized and reconciled. These include the concept of pressure recovery (an overestimation of the true pressure gradient in patients with small mechanical prostheses or small annular dimensions), low-flow aortic stenosis (both with preserved ejection fraction and with low ejection fraction), as well as the problems with calculating a valve area in patients with mixed valve disease.
In these areas of discrepancy between the physical examination and echocardiography, further testing is warranted. There are now a number of different modalities that can be used, including transesophageal echocardiography, CT, CMR, and cardiac catheterization. A Class I indication for cardiac catheterization occurs when there is a discrepancy between the physical examination and echocardiogram. In these cases, measurement of intracardiac and pulmonary pressures, and direct measurement of valve gradients with cardiac output for stenotic lesions and injection of the aortic root and left ventricle for regurgitant lesions, are essential (7).
This important integration of the echocardiogram with the physical examination highlights the necessity of performing a meticulous, comprehensive cardiovascular examination. With the advent of the newer cardiovascular diagnostic imaging modalities, such as echocardiography, CT, and CMR, there has been less emphasis on teaching and performing a proper physical examination. Training programs should re-emphasize the importance of this aspect of cardiovascular medicine, using master clinicians identified at each institution to train the fellows in performing a proper physical examination. There are also tools, not only for the trainees, but also for cardiologists already in practice, such as the American College of Cardiology’s Heart Songs, which have been shown to significantly improve the accuracy of auscultation.
Throughout the ACC/AHA guideline document, there are class recommendations for timing of operation on the basis of cutoff points for left ventricular dimensions and ejection fraction (3). This is particularly true for regurgitant lesions, in which long-standing volume overload can lead to progressive left ventricular dilation and, eventually, to irreversible left ventricular dysfunction. In patients who are asymptomatic, operation may be indicated before the onset of symptoms or heart failure to prevent the adverse consequences of long-standing volume overload on the left ventricle. Thus, cutoff points for ejection fraction and ventricular dimensions have been implemented in the class recommendations, on the basis of natural history studies that document the outcome of patients following operation in relation to pre-operative left ventricular measurements. For instance, in patients with mitral regurgitation, an end-systolic dimension >40 mm and/or an ejection fraction <60% is an indication for intervention, as studies have shown a poor prognosis once this dimension or ejection fraction has been reached. Alternatively, in patients with aortic regurgitation, an end-systolic dimension >50 mm or an ejection fraction <50% have been used for timing of operation.
However, there are a number of caveats when using these cutoff points. First, there is variability in the measurement of these parameters by 2-dimensional and M-mode echocardiography. In a patient with mitral regurgitation, there might be an ejection fraction of 62% on one study, with an ejection fraction of 55% on a subsequent study, due only to variability in measurement or estimation. Thus, particularly in the asymptomatic patient, it is important to document serial changes in size and function of the left ventricle at several points in time, rather than relying on a single measurement at one point in time.
Second, it must also be emphasized that many of these cutoff points have been derived from studies that determine when it is “too late” for intervention, in terms of irreversible left ventricular systolic function. Ventricular size and function are continuous variables, not binary; thus, it is not reasonable to assume that a patient is perfectly fine when his end-systolic dimension is 39 mm but becomes ill when that dimension is reported as 41 mm. Hence, a progressive enlargement in the size of the left ventricle or progressive decrease in its function may be a more appropriate indicator of timing of operation in the asymptomatic patient, before the cutoff points are reached. Finally, the current data are on the basis of left ventricular diameters, which may not reflect the total left ventricular volume due to the geometric changes that occur with volume and pressure overload. In the future, data on the use of volumes by 3-dimensional echocardiography or other imaging modalities, such as CT or CMR scanning, may turn out to be more predictive of outcome.
Assessment of Symptoms
The indication for operation in many valve diseases is the presence of symptoms. However, due to the slowly progressive hemodynamic alterations that occur with chronic valve disease, patients frequently do not perceive a functional limitation. It may be of benefit to ask the spouse or significant other for his or her observation of a patient’s activity level, particularly when the patient claims to be asymptomatic. Formal exercise testing can provide an objective measurement of effort tolerance and, in some patients, may change the patient from being categorized as stage C1 (asymptomatic) to stage D (symptomatic), which has implications for timing of intervention.
Individualizing the Decision to the Institution
To overcome the potential problem of long-standing volume or pressure overload causing damage to the left ventricle, recommendations have been made to operate earlier in the asymptomatic patient, particularly if an operation can be performed with low operative risk. In the case of primary mitral regurgitation, early operation is advised only if a durable valve repair can be performed with a high degree of success. This concept derives from the excellent long-term outcome of successful early operation from highly experienced surgical centers (8). However, not all institutions performing open-heart surgery are able to match the results of the highly experienced centers, in terms of both operative risk and long-term outcome (9).
Thus, to offer early operation to the asymptomatic patient, it is necessary for the clinician to know the individual results of the particular surgeon and institution. This requires transparency of the outcomes data for each surgeon and institution and has led to the concept of “valve centers of excellence,” in which highly experienced valve teams work together to ensure the highest quality of care and high success rates with surgical interventions. This requires that these centers report their outcomes so that the clinician and patient can weigh all risks and benefits when deciding between early operation and “watchful waiting.” It should be the responsibility of the cardiovascular community to promote the collection and retrieval of outcome data for all interventions in patients with valvular heart disease, including not only surgical but also transcatheter procedures. The data need to be granular enough to allow clinicians to make reliable recommendations for individual patients.
Individualizing the Decision to the Patient
The decision to proceed with an intervention must also be individualized for each patient. For instance, surgical aortic valve replacement would be a reasonable intervention for the 72-year-old, still-active runner with very severe aortic stenosis. Alternatively, a 72-year-old obese woman with severe aortic stenosis who has diabetes and multiple other medical problems might be best served with watchful waiting or with transcatheter aortic valve replacement, especially if symptoms are mild or masked by inactivity. It is very important to understand the patient’s own needs and preferences when discussing therapy for valvular heart disease. It truly is a shared decision-making approach that must be undertaken for each individual patient.
The ACC/AHA guidelines have been instrumental in providing a foundation of knowledge for the management of patients with valvular heart disease. However, it is not just a matter of applying all class recommendations to each and every patient with valvular heart disease. One size does not fit all. A “guideline” is just a guideline, and it is the role of the physician to properly incorporate the guidelines into a shared decision with each individual patient.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose. Patrick O’Gara, MD, served as guest editor for this paper.
- Abbreviations and Acronyms
- cardiac magnetic resonance
- computed tomography
- Received December 30, 2015.
- Accepted February 2, 2016.
- 2016 American College of Cardiology Foundation
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