3 3 LA ESCUELA Y LA EDUCACIÓN EN VALORES 3.3.1 Necesidad de educar en valores en la escuela.
3.4. LOS MEDIOS DE COMUNICACIÓN Y LOS VALORES.
3.4.1. Los medios de comunicación como agentes de socialización.
Ethical approval was obtained from the Ethical committee, UBTH, and informed consent was sought from the patients before enrolment into the study.
CHAPTER FOUR RESULTS
VARIABLES OF THE HEART FAILURE POPULATION The mean age of all the cohorts was 56.28 + 16.05 .
The total population was made up of 84 males and 111 females. The male:
female ratio of all the cohorts was 1: 1.3 . The mean duration of HF was 14.23 + 15.88 .
Twenty (22) out of the 36 AF patients were females while 14 were males.
Eighty-nine (89) out of the 159 patients in SR were females while 70 were males.
CARDIAC RHYTHM OF HF PATIENTS
The total population was made up of 36 (18.5%) AF patients,while 159 (81.5%) patients were in sinus rhythm.The cardiac rhythm of those in sinus rhythm were made up of sinus tachycardia 73(37.4% ),sinus bradycardia 15( 7.7%), SR with VPCs 52 ( 26.7%),and SR with APCs 19 ( 9.7%). Prevalence of AF was 18.5%
COMPARISON OF CLINICAL,ECG AND ECHOCARDIOGRAPHIC PARAMETERS
The mean age of the AF group being 48.1 + 16.5 while the mean age of the sinus rhythm ( 58.2 + 15.7)
When the mean age of the AF group was compared to the mean age of sinus rhythm group ,there was a statistically significant difference between them (t=3.3
;p < 0.001 ) .
Mean duration of HF in the AF group was 12.37 + 13.7, while the mean duration of HF in the SR group was 13.89 + 15.6. When the mean duration of HF of the two groups was compared, there was no statistically significant difference between them (t=0.24;p > 0.05) .
Comparison of ECG and Echocardiographic parameters between the 36 AF patients and the 159 sinus rhythm patients was done .There was no statistically significant difference in ventricular rate, QRS axis,QRS voltage and QTc interval ,between the AF and SR group. However, there was a significant difference in left atrial size, left ventricular internal diameter in diastole and systole (LVIDd and LVIDs), fractional shortening, and ejection fraction between the AF group and the SR group(table 3 ) .
Table 1:VARIABLES OF HF POPULATION
Parameter Mean + SD
Age(yrs) 56.28 + 16.05
Duration of HF(months) 14.23 +15.88
Heart rate (bpm) 95.32 + 14.62
Systolic BP (mmHg ) 122.16 + 20.70
Diastolic BP(mmHg ) Sex
78.18 + 14.30 Frequency (%)
Male 84 (43.1)
Female 111 (56.9)
QTc interval LVPW(cm)
448.27 + 28.72 1.1 + 0.38
IVS(cm) 1.1 + 0.31
Left atrial size(cm) 4.03 + 0.84
LVIDd(cm) 5.95 + 1.005
LVIDs(cm) 4.49 + 1.14
Fractional shortening (%) 24.56 + 10.04 Ejection fraction (%) 51.32 + 20.30
Table 2: CARDIAC RHYTHMS OBTAINED IN HEART FAILURE PATIENTS
Rhythm Frequency ( % )
Sinus tachycardia 73 (37.4 )
Sinus bradycardia 15 ( 7.7 )
SR with VPCs
SR with Atrial premature complexes
AF 52 (26.7 ) 19 ( 9.7 ) 36 ( 18.5 )
TOTAL 195 ( 100 )
Table 3: CLINICAL, ECG AND ECHOCARDIOGRAPHIC PARAMETERS OF AF VS SINUS RHYTHM GROUP
Parameter AF SR t statistic P value
n 36 159
Age(yrs) 48.1 + 16.5 58.2 + 15.7 3.3 p < 0.001 Duration of HF 12.37 + 13.7 13.89 + 15.6 0.24 p > 0.05 Ventricular rate 96.3 + 62.4 91.53 +58.4 0.02 p> 0.05 QRS axis ( 0 ) 31.3 + 49.4 25.19 +55.6 0.05 p > 0.05 R1 amplitude (mV) 0.8 + 0.25 1.1 + 0.27 0.17 p > 0.05 SV2+RV6 (mV) 29.0 + 8.0 26.8 + 7.9 1.34 p > 0.05 QTc interval
Left atrial size (cm)
406 + 26.8 4.5 + 2.1
402 + 29.5 2.9 + 1.2
1.48 4.4
p > 0.05 p < 0.001
LVIDd (cm) 6.3 + 2.3 4.1 + 1.6 13.5 p < 0.001
LVIDs ( cm) 4.8 +1.7 4.0 + 1.1 9.1 p < 0.001
IVS(cm) 1.1 + 0.4 1.2 + 0.3 0.4 p > 0.05
LVPW(cm) 1.1 + 0.4 1.2 + 0.4 0.7 p > 0.05
FS (%) 23.6 + 21.6 28.9 + 11.1 2.9 p < 0.001
EF(% ) 50.8 + 14.8 59.2 + 16.9 2.0 p < 0.025
AETIOLOGY OF HEART FAILURE
HHD was the commonest aetiological factor accounting for 112 (57.4%) patients, while DCM and RHD accounted for 38(19.0%) and 32(15.9%) patients respectively. Other aetiological factors were constrictive pericarditis( 2.6% ),cor pulmonale (1.5%),thyrotoxic heart disease (2.1%) and congenital heart disease (1.5%) as shown in figure 1. No ischaemic heart disease was encountered in this study which lasted 12 months.
Table 4 shows the role of aetiology of HF on AF prevalence amongst the patients. RHD had the greatest AF prevalence (40.6%) even though there were only 32 HF patients with rheumatic aetiology .
AF prevalence among the patients with DCM was 15.8% while the AF prevalence for HHD was 12.5% even though HHD accounted for a majority (57.4%) of the total HF population. Rheumatic aetiology showed a strong relationship with AF( p =0.0004) in comparison to HHD (p = 0.001)
Figure 1. AETIOLOGY OF HEART FAILURE.
H H D D C M R H D O t h e r s
57.4%
19.0%
15.9%
7.7%
Table 4: ROLE OF AETIOLOGY OF HF ON AF PREVALENCE
Aetiology of HF AF(%) SR(%) X2 P value
HHD 14 (12.5 ) 98 (87.5) 6.21 0.001
DCM 6 (15.8 ) 32 (84.2) 0.22 0.6
RHD 13 (40.6 ) 19 (59.4) 12.49 0.0004
Others* 3 (23.1 ) 10 (76.9) 0.01 0.9
*Others include constrictive pericarditis, thyrotoxic heart disease, cor pulmonale and congenital heart disease .
SEVERITY OF HEART FAILURE
Table 5 shows the spread of AF and sinus rhythm patients among the four NYHA classes. A greater proportion of AF patients (47.2%) were in severe heart failure (NYHA class IV) compared to those in sinus rhythm (38.2%). Although there seemed to be a tendency to increasing AF with worsening NYHA class, this difference was not statistically significant (Xc2 = 1.76; p = 0.62)
MEDICATIONS
Medications used in this study included Frusemide(100%) while 66.2% of the patients were placed on Digoxin. 89.7% of the patients were placed on an ACE inhibitor while only 5.1% were on a thiazide diuretic. A total of 93(47.7%) were on a calcium channel blocker (CCB), of these, 82(88.2%) were on a dihydropyridine CCB for hypertensive control while 11(11.8%) 6 were on a non- dihydropyridine CCB for rate control of AF with a rapid ventricular response.
94.5% of the patients were placed on spironolactone. This study did not address the arhyythmogenic or protective effect of medical therapy in the patients.
Table 5: COMPARISON OF AF VS SINUS RHYTHM PATIENTS BY NYHA CLASS
NYHA CLASS AF(%)
( n=36 )
Sinus rhythm(%) ( n=159)
I 0 ( 0) 5 (3.1)
II 9 (25) 43 (27.1)
III 10 (27.8) 49 (30.8)
IV 17 (47.2) 62 (39)
Xc2= 1.76;df = 3; p = 0.62
No significant difference in NYHA functional class between the two groups.
FIGURE 2: ECG of patient # 12 with HHD
ECG shows AF, RAD, LVH, with strain pattern ,VTZ in V5 and low voltage complexes in the limb leads.
FIGURE 3: Echocardiogram of patient # 114 with DCM.
Parasternal long axis view showing dilatation of the left ventricle with evidence of poor contractility and wide EPSS, consistent with poor systolic function .
FIGURE 4A and FIGURE 4B
(up) : Apical four-chamber view of patient # 38 with DCM. There is four-chamber dilatation of the heart.
(down) :Parasternal long axis view of the same patient showing a grossly dilated left atrium(5.3cm).
CHAPTER FIVE
DISCUSSION
In this study, HF patients were evaluated for the prevalence of AF. The clinical, electrocardiographic and echocardiograhic parameters associated with the arrhythmia were also dettermined. The prevalence of AF in HF patients reported in this study was 18.5 %.This was slightly higher than the prevalence found in the Veterans Affair Vasodilator in Heart Failure Trials I and II which were 14 and 16% respectively.
The slightly higher prevalence of AF in this study may be attributed to many reasons. Firstly, in the Framingham study, the patients were composed of those with mild- moderate HF, while most of the patients in this study had severe heart failure (NYHA class IV).
The Framingham study reported that severity of HF was associated with a higher tendency to develop AF. Although patients with severe HF tended to have more AF in this study, the difference did not reach statistical significance.
Although there are no other studies on prevalence of AF among HF patients in general, in Nigeria, Omotoso et al13 determined the prevalence of AF among patients with hypertensive heart failure, excluding other causes of HF, and found an AF prevalence of 13%. In this study, when the subset of HF patients with hypertensive heart failure were selected, the prevalence of AF was 12.5 %, comparable to that obtained by Omotoso et al13.
AGE
In this study, increasing age was not found to be related to with development of AF, contrary to previous studies reported among Caucasians7,8 This may be attributed to the high prevalence of AF among RHD patients in this study as RHD is more likely to present at younger age decade in the tropics than among Caucasians. Also, coronary artery disease, whose prevalence increases with age is commoner in Caucasians , and thus will rank above RHD as an aetiology of HF and AF in these Caucasian studies.
SEX
This study showed a male: female ratio of 1:1.3 for the total HF population and a male: female ratio of 1:1.6 for AF. This is comparable with what was found in other studies15 in Nigeria. However, while this study was carried out among HF patients with and without AF, their study population was made up of patients who had presented to them with AF, although 74.4% of these AF patients were in heart failure as well. The finding in this study was however divergent to the finding in the study by Anisiuba et al in Enugu14 where the male: female ratio was 1.3:1. The study in Enugu was among AF patients and not among HF patients, as in this study. The study by Chalak et al16 showed that ischaemic heart disease was the most prevalent cause of AF, followed by RHD and thirdly, HHD.
It was therefore not surprising that their study had a male: female ratio of
1.1:1,since the most prevalent cause of AF in their study, ischaemic heart disease, is known to be commoner in males.
Although AF was commoner in females in this study, this difference was not statistically significant. This may be a reflection of the prevalent underlying heart disease in AF in our environment and also a reflection of gender pattern of use of our facilities.
DURATION OF HF
The mean duration of HF was 14 ± 15.88 months . This study did not reveal any relationship between duration of HF and AF. This may be a reflection of the poor prognosis associated with HF generally, whose mortality rate is about 45% at 1 year55,56.It may therefore be suggested that a good proportion of HF patients die off early, leaving only a few with longer duration of illness, and most of them clustered into shorter duration. This may have weakened the effect of duration of illness on the development of AF.
AETIOLOGY OF HF
HHD was the commonest aetiological factor, accounting for 57.4% of the HF patients. This is consistent with most other studies7, 10, 15. This underscores the importance of systemic hypertension as an aetiological factor for HF. DCM was second to HHD, followed by RHD. This is also similar to the finding in the study
by Mbakwem et al15. Although HHD was the commonest aetiological factor of HF, Rheumatic aetiology, however, had the greatest prevalence of AF, and showed a relationship with AF compared to all the other aetiological factors of HF. RHD which commonly affects the mitral valve, is known to be associated with elevated left atrial pressure as the haemodynamic consequence of the valvular lesion. Elevated left atrial pressure leads to left atrial dilatation. Vaziri et al57 noted AF was commoner in patients with large atria. It may therefore be that the higher prevalence of AF in rheumatic mitral valve disease is due to the larger left atrial sizes in RHD in comparison to other aetiologies of HF.
SEVERITY OF HF
Majority of the HF patients were in NYHA functional class IV. Amongst those with AF, majority fell within NYHA class III and IV, showing that AF is commoner with worsening of heart failure.
Although majority of the patients with AF had moderate-severe heart failure (NYHA functional class III and IV), there was no relationship between the severity of HF and the development of AF (p =0.71). This was surprisingly contrary to the Framingham heart study where prevalence of AF was found to increase with severity of HF (NYHA functional class).This surprising finding was consistent with the lack of significance for association of duration of HF with development of AF. The lack of association between AF and the NYHA functional class may be attributed to the poor spread of patients along the four
NYHA classes and this may have weakened the association between NYHA class and AF, as was for duration of HF.
ECG AND ECHOCARDIOGRAPHIC PARAMETERS
Comparison of electrocardiographic parameters between the AF and sinus rhythm patients showed that there was no significant difference noted in the ventricular rate, QRS axis, QRS voltage and QTC interval between AF and the sinus rhythm patients with HF.
It is noteworthy that there was no significant difference in ECG parameters between AF and the sinus rhythm patients. The ventricular rate was slightly higher in the AF group than the sinus rhythm patients (96.27± 62.4 vs 91.53±
58.4) though it did not reach statistical significance. Ventricular rates tend to the higher when there is AF, and might be a precipitating factor for HF but since Digoxin, anti-arrhythmic drugs (Verapamil) and occasional -blockers were used, this may have reduced the ventricular rate amongst AF patients.
There was no significant difference in QRS axis between the AF patients and the sinus rhythm patients .However the QRS axis was slightly more positive in the AF group (31.26 ± 49.36 vs 25.19 ± 55.61, t=0.05 p>0.05).
There was also no significant difference in mean QRS voltage between the AF group and the sinus rhythm patients. LVH or enlargement is known to produce changes in the QRS complex. The most characteristic finding is increased amplitude of the QRS complex. R waves in leads facing the left ventricle ( i.e
leads 1,aVL,V5 and V6) are taller than normal, whereas S waves in the leads overlying the right ventricle i.e (V1 and V2 )are deeper than normal58.
The lack of significant difference in the mean QRS voltage between the AF group and the sinus rhythm patients may be due to the presence of LVH or LV enlargement in both groups. This is because HHD which causes concentric LVH was present as an aetiology of HF in both groups .
In this study, comparison of echocardiographic parameters between AF and the sinus rhythm patients with showed that there was a strong association between increasing left atrial size, increasing left ventricular dimensions and the development of atrial fibrillation. This is in agreement with the findings of the Framingham heart study57 which examine echocardiographic predictors of AF. In their study, the echocardiographic characteristics of persons who developed AF included larger left atrial, and left ventricular dimensions and ventricular wall thickness, and mitral annular calcification. Each 5mm increase in left atrial dimension increased AF risk 39%. A 5% decrease in left ventricular fractional shortening increased the risk to 34% and a 4mm increase in left ventricular wall thickness increased AF risk 28%.
More recently the cardiovascular health study reported on the predictors of AF in a cohort over the age of 65 years, confirming the role of traditional risk factors and showing that left atrial size was among the strongest independent predictors of AF. This association was linear, with a 60% increase in relative risk of AF for every 1cm in left atrial dimension above 3cm 59.
This study also demonstrated a relationship between reduced fractional shortening and reduced LV ejection fraction and the development of AF.
Similarly, the study by Mbakwem et al 15 also demonstrated the echocardiographic features associated with AF, with majority of their AF patients (84.6%) having enlarged left atrium, and increased left ventricular internal diameter in diastole (51.3%) and systole (61%). They also noted reduced fractional shortening in 76.9% of the patients.
The relationship between reduced fractional shortening and reduced LV ejection fraction and AF may be either cause or effect. On one hand, reduction in fractional shortening and LVEF may be as a result of the rapid ventricular rate commonly associated with AF, leading to electrical and structural remodeling of the left ventricle, with left ventricular dilatation and impairment of systolic function. On the other hand, the sustained atrial overload associated with congestive heart failure causes atrial enlargement that may stimulate stretch-activated channels and increase the vulnerability to AF, as demonstrated in this study and others8 that dilated left atrium is associated with development of AF.
THROMBOEMBOLIC PHENOMENON
Thromboembolic phenomenon was documented in only 1 patient who developed features of an ischaemic CVA. This is contrary to the study by Chalak et al16 where 89.3% of their AF patients had stroke attributable to thromboembolism.
However, that study was carried out amongst AF patients presenting with stroke at the time of inclusion in the study while this study looked at the occurrence of thromboembolic stroke in AF patients who were in HF, and this study not being a follow up study may not determine appropriately the occurrence of thromboembolic features.
CHAPTER SIX
CONCLUSION
From the findings of this study, it may be concluded that HHD remains the commonest aetiology of HF in our environment. This study also shows a relationship between RHD and the development of AF.
Larger left atrial size on echocardiography as well as left ventricular dilatation, evidenced by larger left ventricular internal diameter in diastole and systole, is also related with the development of AF.
Impaired left ventricular systolic function which was determined by reduced fractional shortening and ejection fraction on echocardiography is also related to the development of AF.
Increasing age, severity of HF and the duration of HF were not related to development of AF in this study.
CHAPTER SEVEN
RECOMMMENDATIONS AND LIMITATIONS