Majority of males had normal diastolic function (62%). In the abnormal diastolic function group sex distribution was equal (Table 5).

More than half of the cases with abnormal diastolic function (defined by abnormal E/A ratio) had duration of hypertension more than 12 months (Table 6).

The level of SBP was not significantly associated with diastolic dysfunction as defined by abnormal E/A ratio (Table 7).

Fig. 5: Bar chart showing diastolic blood pressure in normal and abnormal E/A ratio groups

Diastolic blood pressures <80 and ³90 mmHg were significantly associated with abnormal E/A ratio (Table 8).

Incidence of Diastolic dysfunction is more above the age of 40years.

DISCUSSION: Hypertensionis one of the most common diseases afflicting humans throughout the world^{25, 26, and 27}.

The prevalence of hypertension in Indian population is 3.80 to 15.63% in men and 2 to 15.38% in women in urban population and 1.57 to 6.93% in men and 2.38 to 8.81% in women in rural population²⁸.

                Hypertension affects various organs like central nervous system, heart, retina, kidneys and blood vessels. Hypertension affects the heart causing systolic^{29, 30} & diastolic dysfunction³¹, left ventricular hypertrophy³⁰, heart failure³² and contributes to atherosclerotic vascular problems, such as coronary artery disease²⁹.

In recent years there is an increased interest in understanding of diastolic function and its importance in common cardiovascular diseases^{1, 33, 34-38}.

The aim of our study was to assess the diastolic function in hypertensive patients with preserved left ventricular function by transmitral flow velocity curve to detect diastolic dysfunction.

This retrospective cross-sectional study was done on a relatively homogeneous and ambulatory hypertensive population.

Diastolic function is known to be influenced by several interacting factors including age, sex, duration of blood pressure, and LV hypertrophy³⁹, all of which may potentially influence arterial compliance.

Subjects in our study underwent echocardiographic examination where diastolic function was assessed by transmitral flow velocity curves and E/A ratio [ratio of mitral early diastolic filling wave (E) velocity to mitral atrial contraction wave (A) velocity]. In our study, an E/A ratio value of 1.0 was arbitrarily chosen as the lower limit to detect impaired relaxation like in other studies⁴⁰. The values for the E/A ratio observed in our impaired relaxation group (abnormal E/A ratio; 0.80 ± 0.22) were significantly lower than the normal value.

Majority of cases in our study were males (58%). A similar male preponderance was noted in several earlier studies^41-44.

The mean age of cases in our study was 45.70±11.12 years. This was comparable to mean age of cases in the earlier Asian studies. (Masliza et al⁴⁵. mean age 43.1±5.7years), whereas other western studies had enrolled older cases (Mottram et al⁴¹. 58±8 years, Yamamato et al⁴². 69±6years, Mitra et al⁴³. 54.48years, Adewole et al⁴⁴. 59±10.4 years). This may be due to enrollment of follow-up patients with hypertension.

Diastolic dysfunction as defined by E/A ratio was found to be abnormal in 44% of cases in our study. Mottram et al⁴¹. had found abnormal E/A ratio in 40% of their patients which is comparable to our finding. Other investigators have found a lower proportion of cases with abnormal E/A ratio in their study group. Yamamato et al⁴². found abnormal E/A ratio in 31% of their cases, which may be due to lower mean DBP in their cases as compared to our study (74 v/s 91 mm Hg). Masliza et al⁴⁵. found abnormal E/A ratio in only 18.6% of their cases. This could be due to lesser duration of hypertension in their cases. In Masliza’s⁴⁵ study all subjects were newly diagnosed hypertensive (duration less than 6 months), whereas only 32% of subjects were newly diagnosed hypertensive in our study.

Although the sex ratio in abnormal E/A ratio group was equal (50% v/s 50%), more males tended to have normal E/A ratio (62% v/s 48%) in our study. Mottram et al⁴¹. had found that female sex was an independent predictor of diastolic dysfunction. In our study there was a preponderance of female sex with diastolic dysfunction (52% females v/s 38% of males).

Abnormal E/A ratio correlated with DBP ³ 90mm Hg in our study. There was also correlation between normal diastolic function defined by E/A ratio and DBP < 80 mmHg (p=0.004). Mottram et al⁴¹. had also found DBP to be significantly associated with diastolic dysfunction a finding similar to our study.

Our study did not find any association between abnormal E/A ratio and duration of hypertension and systolic blood pressure. No other study except Masliza’s⁴⁵ study had found an association between systolic BP, duration of hypertension and diastolic dysfunction.

Diastolic BP level ³ 90 mmHg was significantly associated with diastolic dysfunction. Mottram et al⁴¹. have also found, elevation in diastolic blood pressure to be significantly associated with diastolic dysfunction. Indeed the study considered the diastolic BP to be an independent risk factor for diastolic dysfunction. Diastolic blood pressure is dependent on peripheral resistance and increases afterload of the heart. Increased afterload may promote myocyte hypertrophy and may also directly slow LV relaxation and contribute to diastolic dysfunction. Our study also found correlation between DBP< 80 mmHg and normal diastolic function (p=0.001). This has not been shown by previous studies.

Although earlier studies had found correlation between left ventricular hypertrophy and diastolic dysfunction⁴⁶, recent studies including our study have not confirmed the association. Masliza et al⁴⁵. also did not find correlation between LVH and diastolic dysfunction and have suggested that a compensatory physiological mechanism in response to pressure load during early hypertension even before onset of demonstrable LVH may be the cause for diastolic dysfunction^{47, 48, 49}.

In our study Diastolic dysfunction in relation to age is more in above 40years of age group; it is comparable to study done by H. Schirmer, P. Lunde et al⁵⁰. lesser incidence in above 55years of age may be due to pseudonormalization in which E/A ratio will be abnormally high due to severe diastolic dysfunction.

Clinical implications: The current findings have potential relevance in clinical practice for evaluation of hypertensive patients as diastolic dysfunction may be an early manifestation of cardiac involvement in hypertension².studies have shown that anti-hypertensive such as ACE inhibitors may be more useful in this condition. The presence of diastolic dysfunction also provides an additional evidence of end-organ damage⁵¹. The frequency of isolated diastolic heart failure in elderly hypertensive patients suggests that asymptomatic hypertensive patients with diastolic dysfunction may be at risk of progression to diastolic heart failure. More longitudinal studies of hypertensive patients with evidence of diastolic dysfunction are needed to determine the predictive value of these noninvasive indicators of diastolic dysfunction.

Study limitations: Our study group consisted of small homogeneous group of hypertensives. As echocardiographic examination could be performed in lesser number of patients than was desirable. Hence, the prevalence of LV diastolic dysfunction obtained in the current study may not be identical when applied to a larger or different population of hypertensives, and a future study with larger population may be required.

The study included patients who were on medications. Diastolic function may be affected by medications as has been shown in several previous studies. This may affect the prevalence of diastolic dysfunction in the current study subjects. The medications were continued by the patients in our study for ethical reasons. In the study diastolic dysfunction was calculated using transmitral flow velocity curve, which fail to detect the diastolic dysfunction in pseudonormal group, which can be detected by studying pulmonary flow velocity curve.

CONCLUSIONS: Diastolic function assessment was done on asymptomatic ambulatory hypertensive patients. Majority were males (58%). The abnormal diastolic function as assessed by abnormal E/A ratio was seen in 44% of cases. There was a preponderance of female sex in this abnormal diastolic function group. Diastolic blood pressure was significantly associated with diastolic dysfunction.

Both decreased and increased diastolic blood pressure was negatively and positively associated with diastolic dysfunction. The diastolic dysfunction was seen in patients with LVH, however this is statistically not significant indicating LVH is not the only cause for diastolic dysfunction in hypertensives.

The current study demonstrated that the presence of LV diastolic dysfunction in hypertensive patients is actually greater than previously reported by studies that analyzed transmitral flow velocity curves.

SUMMARY: Ambulatory hypertensives cases had abnormality in diastolic function (44%) as assessed by transmitral Doppler signals (E/A ratio). The current study demonstrated that the presence of LV diastolic dysfunction in hypertensive patients is actually greater than previously reported by studies that analyzed transmitral flow velocity curves. To avoid overlooking patients with diastolic dysfunction analysis of transmitral flow velocity curves is recommended in all hypertensive patients irrespective of duration of hypertension.

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