|Year : 2013 | Volume
| Issue : 4 | Page : 342-345
Prognosis of diastolic dysfunction: difference in renal function
Department of Internal Medicine, Shebin Elkom Teaching Hospital, Menofia, Egypt
|Date of Submission||12-Aug-2013|
|Date of Acceptance||01-Oct-2013|
|Date of Web Publication||1-Feb-2014|
Department of Internal Medicine, Shebin Elkom Teaching Hospital
Despite the common finding of diastolic dysfunction with preserved ejection fraction on routine echocardiography in elderly patients, it is unknown why some patients with isolated diastolic dysfunction are asymptomatic, whereas others develop diastolic heart failure (i.e. signs and symptoms of congestive heart failure).
The aim of the study is to investigate whether the intrinsic renal insufficiency turn diastolic dysfunction symptomatic.
Patients and methods
We reviewed 80 consecutive patients undergoing transthoracic echocardiography and divided them into two groups: group A, which included 40 patients with diastolic dysfunction without symptoms of heart failure, and group B, which included 40 patients with diastolic dysfunction and symptoms of heart failure. Patient's age, weight and cardiovascular risk factors (hypertension, diabetes and coronary artery disease) were recorded. We used Framingham criteria for congestive heart failure to determine the presence of diastolic heart failure from the symptoms developed, examination findings and radiological studies. Average creatinine clearance and estimated glomerular filtration rate were calculated for each group.
There was difference neither in age or sex nor in the echocardiographic variables of diastolic function or left ventricular hypertrophy between groups. Multiple regression analysis showed that only lower levels of creatinine clearance (74 ± 46 vs. 44 ± 36 ml/min, P = significant) and lower estimated glomerular filtration rate (69 ± 28 vs. 44 ± 33 ml/min/m, P = significant) were associated with diastolic heart failure. There was no significant difference in the presence of hypertension, diabetes and coronary artery disease between two groups.
The results of this study support the hypothesis that patients with normal left ventricular ejection fractions but with diastolic dysfunction develop congestive heart failure because of underlying renal insufficiency. However, a larger prospective study is required to confirm this hypothesis.
Keywords: Diastolic dysfunction, heart failure, renal insufficiency
|How to cite this article:|
Shaeen ES. Prognosis of diastolic dysfunction: difference in renal function. Tanta Med J 2013;41:342-5
| Introduction|| |
Heart failure is a major contributor to morbidity and mortality, with about 3.4 million outpatient visits, one million hospitalizations, and 60 000 deaths attributed to the disease each year in the USA  . Once thought to be caused solely by systolic pump failure manifested by depressed left ventricular ejection fraction (LVEF), it is now known that up to 30-50% of patients with heart failure have isolated diastolic heart failure with preserved LVEF  . It is important to distinguish this clinical syndrome from asymptomatic diastolic dysfunction, which describes mechanical abnormalities of heart during diastole but might be unaccompanied by signs or symptoms of volume overload or congestive heart failure. Asymptomatic diastolic dysfunction is diagnosed using Doppler echocardiography and can be present without any signs or symptoms of congestive heart failure or systolic dysfunction. The prevalence of diastolic dysfunction is unknown, but it is being increasingly recognized and known to increase with age  . This abnormality is often observed on routine echocardiography and might be ignored as unimportant, especially in the elderly. In contrast, isolated diastolic dysfunction with a preserved LVEF is often observed on echocardiographic evaluation of patients with classic heart failure symptoms, and these patients might be categorized as having diastolic heart failure. Diastolic dysfunction can be defined as abnormal relaxation and/or increased stiffness of left ventricle myocardium leading to impaired filling during diastole. A stiff, noncompliant left ventricle with impaired relaxation would result in an elevated left ventricular end-diastolic pressure with consequent increased pulmonary venous pressure  . It is unclear as to why similar abnormalities in diastolic properties of the left ventricle cause only few or no symptoms in some but evident heart failure in others. Because of pressure-volume relationship of left ventricle with impaired diastolic properties, relatively small increase in the ventricular volume might produce a significant increase in left ventricular end-diastolic and pulmonary venous pressure with consequent signs and symptoms of congestive heart failure. This shows that the regulation of volume in patients with diastolic heart failure might be a major factor that determines whether or not a patient develops symptoms  .
| Patients and methods|| |
We reviewed 80 consecutive patients undergoing transthoracic echocardiography from Shebin Elkom Teaching Hospital and divided them into two groups: group A, which included 40 patients with diastolic dysfunction without symptoms of heart failure, and group B, which included 40 patients with diastolic dysfunction and symptoms of heart failure. Patient's age, weight and cardiovascular risk factors (hypertension, diabetes and coronary artery disease) were recorded. We used Framingham criteria for congestive heart failure to determine the presence of diastolic heart failure from the symptoms developed, examination findings and radiological studies. Average creatinine clearance (CrCI) and estimated glomerular filtration rate (eGFR) were calculated for each group.
Echocardiographies were interpreted by experienced echocardiographers. Normal systolic function in this study was defined as LVEF 50% or more. Diastolic dysfunction was determined based on the following echocardiographic criteria  : stage 0 (normal): mitral inflow velocity ratio of early diastolic mitral inflow velocity (E) and atrial filling (A), E/A = 1, deceleration time between 150 and 240 ms, isovolumic relaxation time (IVRT) between 70 and 90 ms and normal left atrial diameter (< 4.1 cm in men and <3.9 cm in women). Stage 1 (impaired relaxation): E/A less than 1. Stage 2 (pseudonormal): E/A between 1 and 1.5, IVRT more than 90 ms and mild-to-moderate left atrial enlargement (4.1-5.1 cm in men and 3.9-4.6 cm in women). Stage 3-4 (restrictive): E/A ratio more than 1.5, at least two of the following deceleration time less than 150 ms, IVRT less than 70 ms and left atrial enlargement (≥ 5.2 cm in men and ≥ 4.7 in women). Significant valvular heart disease was excluded. The primary variable of this study was renal function. This was evaluated using the Cockcroft-Gault equation as follows: CrCI (ml/min) = (140−age) × (weight in kg) × (0.85 if female)/(72 × Cr)  . We also calculated eGFR using the modified diet in renal disease equation as follows: eGFR (ml/min/1.73 m) = 175 × (Cr)−1.154 × (age)−0.203 × (0.742 if female) × (1.212 if African American)  . Age, sex, presence of diabetes or hypertension, signs and symptoms heart failure and chest radiographs were also recorded. To objectively determine whether the participants had heart failure, we used the Framingham criteria for heart failure  . Major criteria for heart failure were paroxysmal nocturnal dyspnoea, neck vein distention, rales, radiographic cardiomegaly, acute pulmonary oedema, an S 3 gallop, increased central venous pressure (>16 cm at right atrium), hepatojugular reflux, or a more than 4.5 kg weight loss in 5 days in response to treatment. Minor criteria were bilateral ankle oedema, nocturnal cough, dyspnoea on ordinary exertion, hepatomegaly, pleural effusion, decrease in vital capacity by third from maximum recorded and tachycardia (heart rate>120 beats/min). Those participants who fulfilled one or two major criteria and two minor criteria without an alternate explanation for their signs and symptoms were placed in the diastolic heart failure group, whereas those who did not meet these criteria were placed in the diastolic dysfunction group.
The Student t-test was used to test statistical differences in the means between groups and the χ2 -test was used to test differences in frequency of population and clinical variables between groups. Multiple regression analysis was used to assess association of population and clinical variables with presence of heart failure. P values of less than 0.05 were considered significant (two-tailed). Values were expressed as mean ± SD.
| Results|| |
Eighty patients were divided into two groups: group A, which included 40 patients with diastolic dysfunction without symptoms of heart failure, and group B, which included 40 patients with diastolic dysfunction who fulfilled the Framingham criteria for congestive heart failure. No significant differences were found between group A and group B with regard to mean age (68 ± 13 vs. 69 ± 12), sex (% male) (48 vs. 44), diabetes (%) (40 vs. 42), coronary artery disease (%) (39 vs. 38); however, significant differences were found between group A and group B with regard to CrCI (76 ± 42 vs. 44 ± 36) and glomerular filtration rate (ml/min/m) (69 ± 28 vs. 44 ± 33) [Table 1].
|Table 1: Demographic and clinical variables of diastolic heart failure group compared with diastolic dysfunction among group|
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Nonsignificant differences in echocardiographic indices between group A and group B with regard to LVEF (%) (61 ± 5 vs. 60 ± 5), left ventricular posterior wall thickness measure at the end of diastole (1.2 ± 0.26 vs. 1.25 ± 0.22), left ventricular interventricular septum thickness measure at the end of diastole (1.46 ± 0.58 vs. 1.21 ± 0.31) and E/A (0.8 ± 0.2 vs. 1.2 ± 0.5) are shown in [Table 2].
|Table 2: Echocardiographic indices of left ventricular diastolic dysfunction|
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Multiple regression analysis of clinical variables associated with diastolic heart failure showed nonsignificant differences with regard to sex, hypertension, diabetes, coronary artery disease, whereas it showed significant differences with regard to glomerular filtration rate and CrCI [Table 3].
|Table 3: Multiple regression analysis of clinical variables associated with diastolic heart failure|
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| Discussion|| |
Heart failure with preserved ejection fraction (HFPEF) is the preferred terminology for diastolic heart failure. There is an important distinction between HFPEF and diastolic dysfunction, which is often a finding on routine echocardiography. Diastolic dysfunction refers to an abnormality of diastolic compliance, filling or relaxation of the ventricle. This can occur in the absence of symptoms classically associated with heart failure (i.e. shortness of breath, fatigue and volume overload). If these signs and symptoms are present in a patient with a normal ejection fraction, they are said to have HFPEF. Generally some evidence of diastolic dysfunction is found in these patients as well  .
A decrease in compliance and diastolic relaxation and an increase in diastolic stiffness of left ventricle are noted in ageing. Echocardiographic index of left ventricular diastolic abnormality are ordinarily adjusted for age. Indeed, evidence of left ventricular diastolic dysfunction is a common finding on routine echocardiography in elderly patients  . There is usually little or no clinical consequence of abnormalities in diastolic function in most patients. However, in some individuals with diastolic abnormalities there are clinical signs and symptoms of congestive heart failure, although the echocardiographic indexes of diastolic dysfunction are not necessarily inappropriate for age and might be similar to those of individuals who are asymptomatic  . In this study, we tested the hypothesis that patients with diastolic dysfunction and normal ejection fractions who develop congestive heart failure have underlying intrinsic renal insufficiency. Congestive symptoms develop because of reduced capacity to clear solute and free water, which is in contrast to individuals who might demonstrate equal degrees of diastolic dysfunction on echocardiography but do not have signs of congestive heart failure  . Because comorbid conditions such as hypertension, coronary artery disease and diabetes mellitus also might produce left ventricular diastolic dysfunction, we determined whether these conditions were more often associated with diastolic heart failure than with asymptomatic diastolic dysfunction alone. On multiple regression analysis, none of these factors were present more often in the heart failure group when compared with the asymptomatic diastolic dysfunction group. Furthermore, according to the study by Victor et al  , race and sex were not found to be major determinants of diastolic heart failure and this was consistent with our hypothesis.
A patient with a normal LVEF but diastolic dysfunction, with or without concomitant heart failure, might have a reduced resting cardiac output  . Abnormal left ventricular relaxation compromises left ventricular filling resulting in reduced left ventricular diastolic volume and attendant stroke volume. Consequently, at a heart rate within the normal resting range cardiac output might be reduced. One could therefore postulate that reduced renal function observed in patients with diastolic heart failure was attributed to a reduction in renal perfusion and not to intrinsic renal insufficiency .
There was no significant difference in left ventricular wall thickness between patients in the diastolic heart failure group and asymptomatic diastolic dysfunction group, suggesting that there was a similar degree of diastolic dysfunction in both groups. Thus, patients in the group with asymptomatic diastolic dysfunction might have the same degree of depression of resting cardiac output with corresponding reduction in renal blood flow causing the same degree of renal insufficiency as in the group of patients with asymptomatic diastolic dysfunction alone  . Therefore, the postulated hypothesis that the reduction in renal perfusion attributed to reduced cardiac output in the group with heart failure only and not in the group with diastolic dysfunction alone might not explain the significant difference in the renal function between the two groups. Nevertheless, we cannot exclude the possibility that invasive testing might have detected different aspects or more complex abnormalities in diastolic function in the heart failure group that were not readily detected by noninvasive Doppler echocardiography used in this investigation. In addition, there was no difference in the frequency of major risk factors for renal insufficiency (hypertension and diabetes), and therefore the renal insufficiency in the heart failure group could not be attributed to these comorbid conditions. However, we cannot exclude the possibility that the heart failure group did have reduced renal perfusion because of coexisting atherosclerotic renal artery disease or other form of renal artery stenosis causing the intrinsic renal insufficiency.
| Conclusion|| |
Renal insufficiency is associated with symptoms of heart failure in patients with echocardiographic indicators of diastolic dysfunction but a preserved LVEF. A prospective and larger study is required to determine whether renal insufficiency is a causative mechanism of heart failure or a secondary effect of heart failure. Patients with asymptomatic diastolic dysfunction can be treated by prophylactic medical therapy to prevent renal insufficiency and consequently future heart failure.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]