Diastolic Dysfunction by Echo Doppler
Abstract & Commentary
Synopsis: Using the Canadian Consensus Guidelines, a majority of patients referred for transthoracic echocardiography have diastolic dysfunction, and the diagnosis of mild and moderate dysfunction were equally common.
Source: Yamada H, et al. J Am Soc Echocardiogr. 2002;15:1238-1244.
Abnormalities of diastolic left ventricular function are recognized to be an important aspect of cardiovascular health in a variety of patients. However, the identification and quantitation of such abnormalities remains controversial. In 1996 the Canadian Consensus Guidelines for the acquisition and interpretation of Doppler echocardiographic indices of diastolic dysfunction were published (J Am Soc Echocardiogr. 1996;9:736-760). Like many committee-derived guidelines, their use in actual clinical practice has not been fully tested. Thus, Yamada and colleagues from the Cleveland Clinic retrospectively evaluated 520 consecutive patients referred to their lab for transthoracic echocardiography. They excluded patients in whom the measurement and interpretation of diastolic parameters would be confounded by their disease process, such as those with mitral valve disease, pericardial effusion, atrial fibrillation, tachycardia, and atrioventricular block. The Canadian categorization of diastolic function is based upon the transmittal and pulmonary venous flow velocity signals, and measurement of the mitral E and A wave velocity ratio (E/A); the deceleration time of the mitral E wave (DT); the systolic and diastolic pulmonary venous flow velocities ratio (S/D); the pulmonary venous atrial systolic reversal velocity (AR); and the difference in the duration of the mitral A wave and the pulmonary A wave reversal velocities (see Table, below).
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Table |
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Canadian Consensus Diastolic Dysfunction Classification by Pulsed Doppler Echocardiography |
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| Grade | E/A | DT(ms) | S/D | AR(m/s) | AR-A(ms) |
| Normal | 1-2 | 150-200 | 1 | < .35 | < 20 |
| Mild | < 1 | > 200 | > 1 | < .35 | < 20 |
| Mild/ moderate | < 1 | > 200 | > 1 | > .35 | > 20 |
| Moderate | 1-2 | 150-200 | 0.5-< 1 | > .35 | > 20 |
| Severe | > 2 | < 150 | < 0.5 | > .35 | > 20 |
Mild dysfunction is considered decreased relaxation with no evidence of increased filling pressure. With mild-to-moderate, increased filling pressure is likely. Moderate is the pseudonormal pattern where filling pressure is definitely elevated. Severe is the restrictive pattern with very increased filling pressure. In addition, they measured other echocardiographic parameters of LV and LA size and function, and reviewed charts for clinical information. LV ejection fraction was estimated and ³ 45% was considered normal. The patients selected ranged in age from 20 to 92 years, their mean age was 62, and 37% were women. Pulsed Doppler mitral velocities were recorded in all patients and 72% had adequate pulmonary venous recordings.
Some abnormality in diastolic function was detected in 75% of the patients. When E/A and DT were adjusted for the known effects of age, 56% still had diastolic dysfunction. The main difference was that the proportion who had mild dysfunction decreased from 39% to 19% after age adjustment. In patients with a normal EF, 45% had diastolic dysfunction as compared to 83% with an abnormal EF. Among those with a structurally normal heart on echo, 26% had diastolic dysfunction compared to 63% with cardiac structural abnormalities. All patients with the diagnosis of heart failure and normal EF had diastolic dysfunction. All patients with moderate or severe diastolic dysfunction had LA enlargement on echo. Yamada et al concluded that, using the Canadian Consensus Guidelines, a majority of patients referred for transthoracic echocardiography have diastolic dysfunction and the diagnosis of mild and moderate dysfunction were equally common.
Comment by Michael H. Crawford, MD
The Canadian schema, the Mayo Clinic one (J Am Coll Cardiol. 1997;30:8-18), and other similar systems are used daily all over the world to label many patients as having abnormal diastolic LV function, yet this is the first assessment I have seen on the magnitude of what we are doing. Even with age adjustment, the majority of patients studied have diastolic dysfunction. Given that many, if not most, people referred for an echo have heart disease, this is perhaps not surprising. On the other hand, could diastolic dysfunction be like mitral valve prolapse in the early 1980s—grossly overdiagnosed? Some of the details of this observational study may shed light on this issue. First, the criteria for moderate and severe diastolic dysfunction with definitely increased filling pressure seem solid, since all such patients had LA enlargement. Second, the classification of mild-to-moderate dysfunction (increased filling pressure likely) seems problematic since only 2% of their patients fell into this category. Even in patients with reduced LVEF or a structurally abnormal heart, the incidence of mild-to-moderate diastolic dysfunction was only 2-4%. The only difference between the mild and the mild-to-moderate category is in the pulmonary venous A reversal velocity measures, which are often difficult to obtain and measure accurately. In fact, in this study, pulmonary venous velocities were recorded in only 72% of patients. Third, the high prevalence of mild diastolic dysfunction in those with a structurally normal heart (26%) and no instances of more severe diastolic abnormalities in these individuals raises concerns that this classification is too sensitive. On the other hand, perhaps this is a marker for early cardiac disease. Unfortunately, we don’t have the data to answer this question. In a patient with risk factors for coronary artery disease or conduction abnormalities on the ECG, this could be an important marker of early LV dysfunction. In apparently healthy individuals it may be worthless. Finally, new techniques such as tissue Doppler imaging, contrast echo, and neurohormone measures may help resolve these issues in the near future. At present, it seems reasonable to call mild and mild-to-moderate diastolic dysfunction by the Canadian criteria, abnormal relaxation-clinical correlation required, and to maintain their classification of moderate and severe.
Dr. Crawford is Professor of Medicine, Mayo Medical School; Consultant in Cardiovascular Diseases, and Director of Research, Mayo Clinic, Scottsdale, AZ.
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