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Year : 2021  |  Volume : 18  |  Issue : 1  |  Page : 5-8

Prevalence of electromechanical dyssynchrony among heart failure patients in a Nigerian tertiary hospital

1 Department of Medicine, Aminu Kano Teaching Hospital, Kano State, Nigeria
2 Department of Medicine, Aminu Kano Teaching Hospital; Department of Medicine, Bayero University, Kano State, Nigeria

Date of Submission13-Jul-2020
Date of Decision19-Sep-2020
Date of Acceptance25-Sep-2020
Date of Web Publication4-May-2021

Correspondence Address:
Dr. Bashir Garba Ahmad
Department of Medicine, Muhammadu Abdullahi Wase Teaching Hospital, Kano State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njbcs.njbcs_4_20

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Context: Heart failure (HF) is among the most important causes of morbidity and mortality worldwide. Cardiac dyssynchrony, a situation associated with a difference in the timing of contractions in different chambers and/or segments of the heart, is frequently seen in patients with HF and is a poor prognostic marker if left untreated. There is limited information on the prevalence of dyssynchrony among HF patientsin our environment. Aims: We set out to assess the prevalence of electromechanical dyssynchrony using electrocardiography and echocardiography among HF patients in a Nigerian tertiary hospital. Settings and Design: We conducted a prospective observational study among adult HF patients in our hospital. Methods and Materials: One hundred patients were consecutively recruited and detailed history and examination were done. Electrical and mechanical dyssynchrony were measured using electrocardiography and echocardiography, respectively. Statistical Analysis: Data were analysed using Microsoft Excel 2003 and the Statistical Package for the Social Sciences version 16 software. Results: A total of 100 participants were recruited, 67% were females. The mean age of the study population was 41.95 ± 16.07 years. Electrical dyssynchrony (QRS ≥120 ms) was found in 11%, interventricular and intraventricular dyssynchrony were seen in 79% and 75%, respectively. There was a significant association between prolonged QRS and intraventricular dyssynchrony, and between inter and intraventricular dyssynchrony. Conclusion: Electromechanical dyssynchrony is prevalent among HF patients in our environment. Larger multicentre studies are needed in our country to fully define the burden of dyssynchrony and study the characteristics of patients with it in order to properly manage them.

Keywords: Heart failure, dyssynchrony, electro cadiogram

How to cite this article:
Ahmad BG, Mijinyawa MS, Sani MU. Prevalence of electromechanical dyssynchrony among heart failure patients in a Nigerian tertiary hospital. Niger J Basic Clin Sci 2021;18:5-8

How to cite this URL:
Ahmad BG, Mijinyawa MS, Sani MU. Prevalence of electromechanical dyssynchrony among heart failure patients in a Nigerian tertiary hospital. Niger J Basic Clin Sci [serial online] 2021 [cited 2022 Aug 9];18:5-8. Available from: https://www.njbcs.net/text.asp?2021/18/1/5/315411

  Introduction Top

Heart failure (HF) is a major and growing public health problem affecting over 37.7 million people worldwide.[1] Unlike developed countries where ischaemic heart disease is the dominant cause of HF, hypertension, cardiomyopathies and valvular disease rank the top three causes of HF in developing regions such as sub-Saharan Africa.[2] In this population, HF also occurs in middle-aged adults, and of equal prevalence in men and women. HF is also associated with high mortality; 50% of HF patients would die within 5 years of diagnosis.[3]

Cardiac dyssynchrony is frequently seen in patients with HF and is a poor prognostic marker if left untreated.[4] Therefore, proper identification of patients with this condition is imperative as patients who have been found to have dyssynchrony can benefit from cardiac resynchronisation therapy (CRT). CRT has been proven to improve symptoms and prognosis among HF patients, mainly through the reduction of left ventricular (LV) dyssynchrony.[3],[5] To the best of our knowledge, cardiac dyssynchrony has not been studied in HF patients in Nigeria. We, therefore, set out to study the prevalence of electrical and mechanical cardiac dyssynchrony among patients with HF presenting at our hospital, Nigeria. Those identified will be recommended for CRT.

  Methods Top

A total of one hundred consenting patients with HF with New York Heart Association (NYHA) functional Class II–IV, who satisfied the inclusion criteria, were recruited consecutively through the emergency unit, medical outpatient clinic and medical wards of our hospital. HF was diagnosed using Framingham criteria.[6]

A detailed history and general physical examination, including a thorough cardiovascular examination, were carried out on all the subjects. They all had anthropometry and their weights and height measured. They also had standard 12-lead surface electrocardiogram (ECG) and an echocardiogram to determine electrical dyssynchrony.

Echocardiography was done using the Sonoscape SSI 8000 cardiac ultrasound system to determine mechanical dyssynchrony. It was done in the left lateral decubitus position using parasternal, short-axis and apical four-chamber views. Two dimensional (2D), M-mode and Doppler echocardiographic evaluation were performed. Using the 2D guided M-mode approach left atrial, LV and other cardiac chambers dimensions were determined.

Echocardiographic parameters of interest included LV preejection interval (LPEI), right ventricular preejection interval (RPEI), and septal to posterior wall motion delay (SPWMD). LPEI and RPEI were defined as the distance measured from QRS onset to the beginning of aortic and pulmonary Doppler flow velocity curves, respectively. The difference between LPEI and RPEI was computed as was regarded as interventricular mechanical delay (IVMD) if ≥40 ms and signifies interventricular dyssynchrony. SPWMD was measured as the time interval between the maximal outward displacement of the interventricular septum and the LV posterior wall, a value of >130 ms 2 standard deviation above the mean of normal controls was considered as the presence of intraventricular dyssynchrony.[4] In patients with difficult to identify systolic peaks of the LV posterior wall or akinetic interventricular septum, intraventricular dyssynchrony was defined as LPEI ≥140 ms.[7] Electrical dyssynchrony was defined by the presence of QRS complex ≥120 ms. [Figure 1] depicts measurements of RPEI and LPEI and IVMD.
Figure 1: Diagram illustrating the intervals of interest in assessment of dyssynchrony using Pulse Wave Doppler technique. Top; Blue arrow indicates right ventricular preejection interval, Red arrow indicates left ventricular preejection interval, while black arrow indicates interventricular mechanical delay. Bottom; electrocardiogram tracing to give corresponding electrical activity of the heart

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Data analysis

The analysis was performed using SPSS Inc. Released 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc. Chi-square test was used to check for the association between categorical variables, and t-test or ANOVA, where appropriate, was used to check for differences between two and three groups of continuous variables, respectively. Binary logistic regression analysis was used to determine predictors of the dependent variable. The level of significant difference between those with and without dyssynchrony was determined, and in the whole analysis, P < 0.05 was considered as statistically significant.

  Results Top

The mean age of participants was 41.95 ± 16.07 years, 67% were female. The mean body mass index (BMI) of the participants was 22.2 ± 6.2Kg/m2, while means of pulse rate, systolic blood pressure, and diastolic blood pressure were 107.4 ± 19.0 beats per min, 113.7 ± 23.7 mmHg, and 77.4 ± 16.1 mmHg, respectively. Fifteen percent (15%) were underweight while only 6% had a BMI ≥30 kg/m2.

The grouping of the participants, according to the NYHA functional classification of HF symptoms. Majority (71%) falls within NYHA class III, but only 14% were in NYHA II.

The commonest presenting symptoms were cough, dyspnoea on exertion, paroxysmal nocturnal dyspnoea, and orthopnoea. The distribution is shown in [Figure 2]. Seventy-one percent presented with pedal swelling, 42% with palpitations, and chest pain was reported by 14% of the study participants.
Figure 2: Distribution of symptoms of the participants

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[Figure 3] illustrates the echocardiographic diagnoses of HF aetiology among the study participants. Majority (44%) had hypertensive heart disease as the cause of HF, while ischaemic heart disease contributes to only 4%.
Figure 3: Echocardiographic diagnoses of the study participants

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Analysis of the QRS complex showed that 11% had a prolonged QRS ≥120 msonds, whereas the remaining had a QRS duration <120 ms. Further subgrouping of those with prolonged QRS revealed that 8 (73%) of them had QRS width between 120 and 150 ms, while in three (27%), the QRS width was above 150 ms. Five percent of the subjects had left bundle branch block (LBBB) morphology on the resting ECG.

Prevalence of interventricular dyssynchrony (LPEI–RPEI ≥40 ms) was found to be 79%, while that of intraventricular (SPWMD >130 ms) was 75% among the study participants [Figure 4].
Figure 4: Prevalence of mechanical dyssynchrony

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  Discussion Top

Electromechanical dyssynchrony is an important predictor of outcome among patients with HF.[8],[9],[10],[11] Such information among the teaming HF populace in Nigeria is needed to improve management and outcome.

Eleven percent (11%) had a prolonged QRS complex greater ≥120 msonds. Most of the published Nigerian HF studies did not assess the prevalence of electrical dyssynchrony. Our value was lower than the 20% found in an Abidjan study among patients with dilated cardiomyopathy and severe LV dysfunction.[12] Emkanjoo et al. found 51.5% prevalence among HF patients in Tehran[13] while Kashani and Barold found 14%–47% among HF cases in the USA.[14] The higher values observed in their studies could be because of more ischaemic heart disease burden in their countries, compared to our cohort. Five percent of the subjects had LBBB morphology on the resting ECG. This correlates well with the electrical dyssynchrony, which is based on QRS prolongation. LBBB results from interruption of electrical impulse propagation in the left bundle branch, leaving the rest of the LV myocardium to be depolarised indirectly by the right bundle branch via cell to cell conduction. This leads to the prolongation of isovolumic contraction and relaxation phases of the cardiac cycle, resulting in shortened ventricular ejection and filling times and eventual fall in stroke volume and cardiac output.[15] Both QRS prolongation and LBBB morphology have been important determinants of response to CRT.[10],[14]

Prevalence of interventricular dyssynchrony (LPEI–RPEI ≥40 ms) was found to be 79%, which is much higher than 47.5% and 38% found in the Abidjan[12] and USA, respectively.[14] This difference could be attributed to the fact that most of the patients in this study have moderate to severe HF (NYHA classification). Interventricular dyssynchrony is an indicator of disorganized and nonsequential contraction of ventricles, subsequently undermining the function of the heart as single effective pump.[15],[16] In prolonged QRS duration, depolarisation is replaced by a diffuse activation wave travelling throughout the myocardial wall in a haphazard fashion, generating abnormal loading conditions in segments of the ventricle, causing additional localised fibrosis and hypertrophy leading to mechanical dyssynchrony.[8],[15] It can be a cause or consequence of HF, and has been noted with varying prevalence among patients with HF.[3],[9],[15] Prevalence of intraventricular dyssynchrony was found to be 75% in this study, a finding similar to the 70% from Abidjan.[12] Interventricular and intraventricular dyssynchrony constitute ventricular mechanical dyssynchrony. Dyssynchrony occurs for several reasons, including electrical delay, myocardial ischaemia and abnormal loading conditions.[4] In myocardial ischaemia, impaired regional contractility and wall motion abnormalities produce mechanical dyssynchrony without disturbing electrical conduction. Thus, several studies have documented the presence of mechanical dyssynchrony in HF patients with normal QRS duration.[10],[13],[16],[17],[18],[19],[20],[21]

  Conclusion Top

The patients in this study were relatively young and there were more females than males with male-to-female ratio of 1:2. The prevalence of electrical dyssynchrony (QRS ≥120 ms) was 11%, interventricular dyssynchrony was 79%, and intraventricular (or LV) dyssynchrony was 75%. Electromechanical dyssynchrony is prevalent among Nigerians with HF. Larger studies need to be done to identify these patients so that they are referred for appropriate treatment.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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Helm P, Beg MF, Miller MI, Winslow RL. Measuring and mapping cardiac fiber and laminar architecture using diffusion tensor MR imaging. Ann N Y Acad Sci 2005;1047:296-307.  Back to cited text no. 9
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Haghjoo M, Bagherzadeh A, Fazelifar AF, Haghighi ZO, Esmaielzadeh M, Alizadeh A, et al. Prevalence of mechanical dyssynchrony in heart failure patients with different QRS durations. Pacing Clin Electrophysiol 2007;30:616-22.  Back to cited text no. 11
Anzouan-Kacou JB, Ncho-Mottoh MP, Konin C, N'Guetta AR, Ekou KA, Koffi BJ, et al. Prevalence of cardiac dyssynchrony and correlation with atrio-ventricular block and QRS width in dilated cardiomyopathy: An echocardiographic study. Cardiovasc J Afr 2012;23:385-8.  Back to cited text no. 12
Emkanjoo Z, Esmaeilzadeh M, Mohammad Hadi N, Alizadeh A, Tayyebi M, Sadr-Ameli MA. Frequency of inter- and intraventricular dyssynchrony in patients with heart failure according to QRS width. Europace 2007;9:1171-6.  Back to cited text no. 13
Kashani A, Barold SS. Significance of QRS complex duration in patients with heart failure. J Am Coll Cardiol 2005;46:2183-92.  Back to cited text no. 14
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Spragg D, Berger R, Kass D, Calkins H. Left ventricular dyssynchrony and cardiac resynchronization theraphy. In: Textbook of Cardiovascular Medicine. Topol Ej, editor 3rd ed. Lippincott Williams & Wilkins; 2007. p. 1212-23.  Back to cited text no. 18
Bleeker GB, Schalij MJ, Molhoek SG, Verwey HF, Holman ER, Boersma E, et al. Relationship between QRS duration and left ventricular dyssynchrony in patients with end-stage heart failure. J Cardiovasc Electrophysiol 2004;15:544-9.  Back to cited text no. 19
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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