Estándares de Calidad Educativa

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is a paradox. The mean waist circumference is also found to be lower in the patients than in the controls. However, the mean height in the patients is comparable with that of the controls.

Evaluation of systolic BP in the patients showed that it was similar to that of the controls.

Although high blood pressure (HBP) remains the commonest cause of HF in our environment, the evolution of HBP is characterized by progressive decline in BP with increasing myocardial damage and advancing HF such that the BP falsely normalises and indeed the BP may be lower than normal at late stage of the condition.

In this study, the electrolyte and urea in the patients were similar to those in the controls but the creatinine was higher in the patients compared with the controls. The mean eGFR in the patients was also lower compared with that of the controls. This may be attributed to renal impairment that is common in the patients with HF due to similar aetiology of both heart and renal disease conditions i.e. hypertension, DM and other causes of HF. Furthermore, there is reduction of renal perfusion in HF causing renal ischaemia and reduction of GFR. Patients with renal hypoperfusion or intrinsic renal disease show an impaired response to diuretics and ACEI and are at increased risk of adverse effects during treatment with digitalis. A recent meta- analysis revealed that most HF patients had some degree of renal impairment and this represents a high risk group with an increased relative mortality risk when compared with patients with normal renal function.⁹⁰ Renal insufficiency is emerging as a strong independent predictor of adverse outcomes in HF patients.^91,92

6.1 THE RELATIONSHIP BETWEEN PLASMA BNP AND ECHO LV INDICES IN

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plasma BNP level in the healthy controls was below the recommended cut-off value of 100pg/ml. Though ethno-racial variability was proposed by Montagnana M et al¹⁴ and Abdulle AM et al,¹⁵ this was not evaluated in the present study since it was carried out among the blacks only. However, the observed mean BNP in the healthy controls was still within the acceptable cut-off value observed in the Caucasian studies.

Furthermore, gender variability of BNP was observed in this study among healthy controls. The mean BNP level in female healthy controls (81.8±50.8pg/ml) was higher than that of male controls (77.1±43.7pg/ml). The observed gender differences could not be attributed to age or worsening renal functions because there were no significant differences in age and the renal function in both male and female controls. However, this tally with findings obtained in other studies 37,57,93,94 where they also observed similar higher values in the female than male. However, the reason for the gender related differences is still not clear, but may be caused by higher wall stress in the smaller female heart.²⁹ There may also be a stimulatory effect of female sex hormones on the peptide gene expression⁹⁵ and an extra-cardiac source of the peptide in female reproductive tract⁹⁶ In both genders, increasing natriuretic peptide was related to decreasing free testosterone and increasing sex hormone binding globulin SHBG concentration. This suggests that testosterone may exert a suppressive effect on the natriuretic peptides system and thus mediate a BNP deficiency in men compared to women.⁹⁷ On the other hand, estrogens exert a stimulatory effect on natriuretic peptide in post- menopausal women⁹⁸ and administration of estrogens produced a rise in plasma BNP⁹⁹. Studies on circulating cardiovascular biomarkers such as natriuretic peptides may provide a biologic basis to better understand the gender differences in cardiovascular risk. Thus, the lower BNP may be the explanation for the lack of cardiovascular protection in men compared to women¹⁰⁰. This finding underscores the importance of having different cut- off values of the peptide in women and men.

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The gender comparison of anthropometric, biochemical and Echo indices in patients with HF revealed similar and comparable means in these parameters except LVIDd and LVIDs.

LVIDd and LVIDs (P= 0.007 and 0.011 respectively) were significantly higher in the male patients than in the females. In the same vein, the mean plasma BNP level was significantly higher in male patients than in the females. These differences could be due to significant difference in LV internal dimension observed in this study as well as worse systolic dysfunction in the male than the female patients, however, the males were more ill than the females as shown in Table 6.

Despite the fact that this study was carried out in patients presenting newly with clinical features of HF, majority were in NYHA class III (57.5%), followed by class IV (22.5%) and class II (20%) and none was in class I. This is a reflection of late presentation of HF patients to hospitals, paucity of health care facilities, ignorance about the symptoms of the disease and poverty. However, the mean BNP level was observed to be progressively increasing according to the severity of the patients NYHA functional class. This was observed in similar studies by Wieczoreck SJ et al¹⁰¹ and Jabar et al¹⁰² amongst Caucasians and Pakistani populations respectively.

The Echo parameters in patients and controls are represented in Tables 8 and 9 for LV systolic and diastolic indices respectively. It is significant to note that the mean LVMI in the controls were 139.5±27 and 111.9±23g/m² for male and female respectively. This mean LVMI observed in the healthy controls in this study is slightly above the recommended cut- off value for upper limit of normal by ASE^{75, 79} despite screening the controls with ECG.

However, it is not surprising because ASE criteria was based on Caucasian Echo indices.

Blacks are more muscular and may have higher LVMI. Although, Echo is more sensitive and specific for LVH than ECG as observed by Katibi et al⁸⁰ when they compared various ECG criteria for the diagnosis of LVH and Echo in adult Nigerians. Similar higher LVMI was

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reported by Katibi et al¹⁰³ among normal adult Nigerians culminating in the recommendation for a larger multicentre study for the establishment of new normal limits of LVMI for Nigerians.¹⁰³

The mean LVIDd and LVIDs in the patients were significantly higher than in the controls (P<0.001). This is not unexpected in patient presenting with symptomatic HF, because HF patients usually have increased LV end diastolic volume and/ or pressure overload leading to cardiac remodelling, hypertrophy and dilatation of the ventricles. Similarly in this study, the mean FS and EF were significantly lower in the patients (22.4% and 43.3%) compared with the controls (39% and 69.8%) (P<0.001). However, this is an expected trend because the former were in HF while the latter were not in failure. The mean LAD is higher in the patients (39.8±7.5) than the controls (32±4.3) P<0.001 which is a reflection of high LV filling pressure in patients with HF. This increased LV filling pressure stimulates the cardiac myocyte to secrete the natriuretic peptides.

The LV diastolic parameters showed a significantly higher E/A ratio in the patients (2.03±1.47) than in the controls (1.29±0.27) P <0.001. This observation is in keeping with the fact that diastolic HF is common among patients with HF, one- half of HF patients have normal or preserved ejection fraction.² The mean IVRT was found to be prolonged in the patients than in the controls. This is however expected in the HF patients due to impaired diastolic functions.