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NewsletterLiterature Reviews Prevalence of Left Ventricular Diastolic Dysfunction by Doppler Echocardiography: Clinical applications of the Canadian Consensus Guidelines Yamada H, et al. J Am Soc Echocardiography 2002; 15: 1238-44
Reviewers: Feroze Mahmood, MD
Background: Diastolic dysfunction is increasingly recognized as a cause of congestive heart failure, especially in patients with normal systolic function. The therapeutic approach to treatment of diastolic failure is different from the approach used to treat systolic heart failure, as diastolic failure precedes the systolic failure. With the advent of Doppler echocardiography, it has become easier to diagnose and grade diastolic dysfunction with serial measurements using pulmonary venous inflow (PVF) and trans mitral flow (TMF) patterns and monitor diastolic function response to treatment. Canadian Consensus guidelines1 have been developed to standardize the diagnosis of diastolic dysfunction using echocardiography and this paper is an attempt at application of these guidelines to assess the prevalence of diastolic dysfunction. Methods: This is a retrospective study of 520 patients referred for transthoracic echocardiographic (TTE) studies. Patients with severe mitral regurgitation, mitral stenosis, mitral prosthesis or repair, pericardial tamponade and restriction were excluded from the study, as were patients with atrial fibrillation, tachycardia (HR > 120) and heart block due to difficulty in interpretation of the flow patterns. However, patients with mild to moderate aortic regurgitation were included in the study. In recording TMF, deceleration time (DT), E/A wave duration and ratio were measured and calculated. In PVF assessment, systolic to diastolic flow ratio (S/D) and duration of atrial reversal (AR) were recorded and the difference between AR and duration of "a" wave (AR-A) was also recorded. On the basis of the Canadian Consensus guidelines (Table 1), the patients were classified into having normal diastolic function, mild diastolic dysfunction (impaired relaxation and normal filling pressures at rest), mild to moderate diastolic dysfunction (impaired relaxation and likely elevated filling pressures), moderate diastolic dysfunction (increased left ventricular (LV) filling pressures with pseudo normal pattern) and severe diastolic dysfunction (high LV filling pressures and restrictive pattern). At least 4 out of 5 criteria had to be fulfilled to assign into a specific group. The effect of age on LV diastolic filling pattern was distinguished from a true relaxation abnormality using 95% confidence limits for E/A ratio and DT for age and gender reported from a previous study by Klein et al2. In patients with abnormal relaxation, only those with parameters beyond the 95% confidence limit for age were classified as having a true relaxation abnormality. Sizes of left atrium and LV and LV ejection fraction (EF) were also measured during TTE study. Results: The reasons for referral for TTEs were coronary artery disease (27%), valvular heart disease (26%), heart failure (25%), hypertension (8%), and other miscellaneous causes (14%). The mean age of the patients was 62±15 years, and there were 326 men (63%) and 194 women (37%). They were able to record TMF patterns in all the patients; however, PVF patterns were recorded only in 72% of the cases. Of the 520 patients, 290 (56%) had abnormal diastolic dysfunction as described by the Canadian consensus guidelines, after correction for age. Among those patients (N=372) with normal LV systolic function (EF>45%), 167 had abnormal diastolic function with 85 (51%) having mild dysfunction, 2 (1%) having mild to moderate dysfunction, 65 (39%) having moderate dysfunction and 15 (9%) having severe dysfunction. Diastolic dysfunction was more common in patients with structural abnormality of the heart. Of the patients with normal hearts (N=104), 74% had normal diastolic function, and the remainder had mild diastolic dysfunction and none had moderate or severe dysfunction. Conversely, in patients with structural abnormalities of the heart (N=416), 64 (15%) had severe diastolic dysfunction, 112 (27%) had moderate dysfunction, 8 (2%) had mild to moderate dysfunction, 79 (19%) had mild dysfunction, and only 153 (37%) had normal diastolic function. Patients referred for coronary artery disease (64%) and hypertension (58%) had more abnormal diastolic function than those referred for miscellaneous causes (40%). Patient >50 years in age had a higher prevalence of diastolic dysfunction than the younger age group (60% vs. 40%). At the time of echocardiography, 99 patients had features of congestive heart failure, of which 38 (38%) had preserved systolic function, thus primary diastolic heart failure. Discussion and Comments: Unlike ventricular systolic function, of which ejection fraction is often used as a measure on a linear scale, there is no convenient linear scale measuring diastolic function. Canadian consensus guidelines represent one attempt at providing a semi-linear scale of diastolic dysfunction from mild to severe, based on TMF and PVF. A similar grading system, proposed by the Mayo Clinic, utilizes TMF only and is based on the presumed progression of diastolic dysfunction from normal, grade 1 (abnormal relaxation), grade 2 (pseudonormal), grade 3 (reversible restrictive), to grade 4 (irreversible restrictive)3. The significance of this study lies in demonstration of the extent of applicability of the linear scale of Canadian consensus guidelines in everyday practice. Whereas TMF could be measured in 100 % of the study patients, PVF was measurable in only 72 %, so that fully in 28 %, the scale of the guidelines could not be applied and classification had to be based on TMF only. Furthermore, since the study excluded patients with mitral disease or prosthesis, pericardial tamponade, constriction, atrial fibrillation, tachycardia, and atrioventricular block, the applicability of the guidelines in these patients remains unknown. On the other hand, since the study performed a retrospective analysis of echocardiographic data obtained for indications which might not have been for the purpose of diagnosing diastolic dysfunction, it is possible that had TTE been performed specifically for the purpose of examining PVF as well as TMF, feasibility of measurement might have been higher. In addition, intraoperatively when one uses TEE instead of TTE, feasibility of measurement of PVF as well as TMF - and therefore, applicability of the Canadian consensus guidelines - is likely to be much higher, probably approaching 100%4. Secondly, as the authors themselves point out, both TMF and PVF patterns depend on atrial and ventricular loading conditions such as hydration status, heart rate, posture, and medications. It may be difficult to separate the effect of these dynamic changes from intrinsic diastolic properties of the myocardium. An ideal scale of diastolic dysfunction should be based on load-independent measures. In this regard, it is of interest that mitral annulus velocity during diastole5 and peak early velocity longitudinal axis expansion6 measured by Doppler tissue imaging have been reported to be preload-independent. In addition, color M-mode Doppler echocardiography may be a tool to distinguish normal and pseudonormal patterns7, independent on loading conditions. Thirdly, in this study, the prevalence of primary diastolic heart failure (DHF) was 38%. A definitive diagnosis of DHF requires clinical evidence of heart failure in conjunction with objective evidence of normal LV systolic function (EF 3 50 %) and diastolic dysfunction8. A consensus scale of diastolic dysfunction such as Canadian consensus guidelines or Mayo Clinic grading system would be a prerequisite to not only making a verifiable, objective diagnosis of DHF, but also assessing the response to any treatment. In this study, those patients with primary DHF tended to be older, with a history of coronary artery disease and hypertension, and were usually less symptomatic than those with systolic heart failure - being minimally symptomatic at rest, but becoming symptomatic with tachycardia or exercise when diastolic filling time was shortened. Thus at least a subset of these patients with a primary DHF may be at an early stage of heart failure with potentially reversible abnormalities. Making an early diagnosis with a consensus grading system is therefore all the more important.  References 1. Rakowski H, Appleton CP, Chan KL, et al. Canadian consensus recommendations for the measurement and reporting of diastolic dysfunction by echocardiography: from the Investigators of Consensus on Diastolic Dysfunction by Echocardiography. J Am Soc Echocardiogr 1996; 9:736-60. 2. Klein AL, Burstow DJ, Tajik AJ, et al. Effects of age on left ventricular dimensions and filling dynamics in 117 normal persons. Mayo Clin Proc 1994; 69:212-24. 3. Nishmura RA, Rajik AJ. Evaluation of diastolic filling of left ventricle in health and disease: Doppler echocardiography is the clinician's Rosetta stone. J Am Coll Cardiol 1997; 30:8-18 4. Tabata T, Kabbani SS, Murray RD, et al. Difference in the respiratory variation between pulmonary venous and mitral inflow Doppler velocities in patients with constrictive pericarditis with and without atrial fibrillation. J Am Coll Cardiol 2001; 37:1936-42 5. Sohn DW, Chai IH, Lee DJ, et al. Assessment of mitral annulus velocity by Doppler tissue imaging in the evaluation of left ventricular diastolic function. J Am Coll Cardiol 1997; 30:474-80 6. Garcia MJ, Rodriguez L, Ares M, et al. Differentiation of constrictive pericarditis from restrictive cardiomyopathy: assessment of left ventricular diastolic velocities in longitudinal axis by Doppler tissue imaging. J Am Coll Cardiol 1996; 27:108-14 7. Takatsuji H, Mikami T, Urasawa K, et al. A new approach for evaluation of left ventricular diastolic function: spatial and temporal analysis of left ventricular filling flow propagation by color M-mode Doppler echocardiography. J Am Coll Cardiol 1996; 27:365-71 8. Vasan RS, Levy D. Defining diastolic heart failure: a call for standardized diagnostic criteria. Circulation 2000; 101: 21:2118-21 Table of Contents:
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