Download The Prevalence of Electrocardiographic Abnormalities in a Dilated

The Prevalence of Electrocardiographic Abnormalities in a Dilated Cardiomyopathy Cohort Characterised by Cardiovascular
Magnetic Resonance
Ankur Gulati, Nizar Ismail, Tevfik Ismail, Andrew Jabbour, Kishen Morajij, Carla Goncalves, Sadaf Raza, Maria Paes, Francisco Alpendurada, Dudley Pennell, Sanjay Prasad
National Heart and Lung Institute, Imperial College, NIHR Cardiovascular Biomedical Research Unit and Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom
Introduction
Results
Conclusions
The electrocardiogram (ECG) is one of the most commonly performed investigations in
cardiovascular patients. Heart failure (HF) is a common condition that is associated with
significant morbidity and mortality.1 Guidelines from NICE recommend that an ECG is
performed in every patient suspected to have HF.2
Baseline cohort characteristics are summarised in Table 1. ECG abnormalities are
displayed in Table 2. Notably, only 17% of DCM patients had a normal ECG. Common
ECG abnormalities included left bundle-branch block, T-wave inversion, left axis
deviation and left ventricular hypertrophy. Other prevalent abnormalities include left atrial
enlargement, ventricular ectopy and atrial fibrillation.
There is a high prevalence of ECG abnormalities in patients with DCM characterised
by cardiovascular magnetic resonance (CMR).
Patients who had a normal ECG had a significantly higher left ventricular ejection fraction
(EF) (50% [8] vs. 37% [27], mean [SD]; p<0.001), a lower mean indexed end-diastolic
volume (124 ml/m2 [31] vs. 142 ml/m2 [47]; p=0.003), and a lower mean indexed endsystolic volume (75 ml/m2 [33] vs. 100 ml/m2 [47]; p<0.001) than DCM patients who had
an abnormal ECG.
Patients with severely impaired LV systolic function were more likely to have left atrial
enlargement (31% vs. 8%) and T-wave inversion (36% vs. 18%) compared to those with
mild or moderate LV systolic impairment.
After ischaemic heart disease, dilated cardiomyopathy (DCM) is the most common
cause of HF.3 Cardiovascular magnetic resonance (CMR) imaging is the gold standard
investigation for the evaluation of patients with DCM.4 It provides accurate, reproducible,
quantitative assessment of ventricular volumes, mass and function and also enables
detection of mid-wall fibrosis.
Despite the fact that DCM is common cause of HF and the ECG is an essential
screening tool for HF patients, the prevalence of ECG abnormalities in patients with
DCM has not been well described. We therefore examined the nature and prevalence of
ECG abnormalities in a cohort of DCM patients who were comprehensively
characterised by CMR.
Table 3 compares the prevalence of ECG abnormalities between DCM patients with
severely impaired LV systolic function (EF≤35%) versus mild or moderate LV systolic
impairment (EF>35%). Patients with severely impaired LV systolic function were more
likely to have left atrial enlargement and T-wave inversion.
Characteristic
Methods
Total number of patients
Consecutive patients with suspected or known DCM who were referred for CMR
evaluation between January 2009 and October 2010 were prospectively enrolled.
Patients with a clinical history of previous myocardial infarction or coronary artery
disease were excluded. Other exclusion criteria included significant primary valvular
disease, hypertrophic cardiomyopathy or any evidence of infiltrative heart disease. The
final diagnosis of DCM was corroborated by CMR findings in 157 patients. All patients
had increased indexed left ventricular (LV) volumes and reduced ejection fraction (EF)
normalised for age and sex, with no evidence of myocardial infarction on late gadolinium
enhancement imaging. Significant coronary artery disease was additionally excluded in
137 patients by coronary angiography or non-invasive stress imaging studies.
CMR (Siemens Sonata, 1.5-T, Erlangen, Germany) was performed using steady-state,
free precession breath-hold cines (TE [echo time]/TR [repetition time] 1.6/3.2 ms, flip
angle 60°) in long-axis planes and sequential 7-mm short-axis slices (3-mm gap) from
the atrioventricular ring to the apex at the Royal Brompton Hospital. The late gadolinium
enhancement (LGE) images were acquired 10 minutes after intravenous gadoliniumDTPA in identical short-axis planes using an inversion-recovery gradient echo sequence.
Inversion times were adjusted to null normal myocardium. Ventricular volumes and
function were measured for both ventricles using standard techniques and analysed by a
cardiac imaging specialist using semi-automated software (CMRtools, Cardiovascular
Imaging Solutions, London, United Kingdom).
Prevalence
157
Age (years)
52 (14)
Male
104 (66)
Family history of DCM
18 (11)
(B)
(C)
(D)
Figure 1: CMR Images of a patient with DCM and extensive mid-wall fibrosis. (A) Four-chamber view (FCH) in enddiastole (B) FCH view in end-systole (C and D) FCH and short-axis views demonstrating mid-wall late gadolinium
enhancement (arrow).
A standard 12-lead ECG was performed on the same day as the CMR scan for each
patient. All ECG’s were scored for any abnormality by two blinded cardiologists as per
the “AHA/ACCF/HRS Recommendations for Standardization and Interpretation of the
Electrocardiogram.5
Prevalence (n=157)
Normal ECG
26 (17)
Abnormal ECG
131 (83)
Atrial fibrillation
21 (13)
First degree AV block
10 (6)
Left atrial enlargement
28 (18)
Left axis deviation
31 (20)
Left bundle-branch block
40 (25)
30 (19)
Hypercholesterolaemia
46 (30)
Hypertension
35 (22)
Current smoker
17 (11)
Left ventricular hypertrophy*
History of alcohol excess
16 (10)
Pathological Q waves
5 (3)
Diabetes
10 (6)
Right atrial enlargement
5 (3)
Systolic blood pressure (mm Hg)
123 (18)
Right axis deviation
7 (4)
Diastolic blood pressure (mm Hg)
76 (12)
Right bundle-branch block
2 (1)
Heart rate (beats/min)
79 (16)
ST segment depression
7 (4)
NYHA functional class
I
68 (42)
II
46 (29)
III
39 (24)
IV
4 (3)
Medications
T-wave inversion
31 (20)
Ventricular ectopy
22 (14)
Our study highlights the diagnostic value of the ECG in the assessment of patients with
suspected DCM.
Further work is required to evaluate the prognostic significance of ECG abnormalities in
the DCM population.
This project was supported by the NIHR Cardiovascular Biomedical Research Unit of
Royal Brompton and Harefield NHS Foundation Trust and CORDA. Dr Andrew Jabbour
was supported by a Neil Hamilton Fairley Postdoctoral Research Fellowship from the
National Health and Medical Research Council of Australia, the Royal Australasian
College of Physicians, the St Vincent’s Clinic Foundation.
References
Severe LV
Systolic
Impairment
(n=61)
Mild or
Moderate LV
Systolic
Impairment
(n=96)
P
value
ACEi
118 (75)
Beta-blocker
111 (71)
Atrial fibrillation
11 (18)
10 (10)
0.23
Loop diuretic
71 (45)
Left atrial enlargement
19 (31)
9 (9)
0.001
Aspirin
51 (32)
Left axis deviation
16 (26)
15 (16)
0.15
Statin
47 (30)
Left bundle-branch
block
19 (31)
21 (22)
0.25
Warfarin
35 (22)
14 (23)
16 (17)
0.41
Digoxin
21 (13)
Left ventricular
hypertrophy*
Pathological Q waves
2 (3)
3 (3)
1.0
LV EDVi (ml/m2)
130 (38)
Right atrial
enlargement
4 (7)
1 (1)
0.07
LV ESVi (ml/m2)
84 (40)
Right axis deviation
5 (8)
2 (2)
0.11
LV EF (%)
38 (14)
1 (2)
1 (1)
1.0
Midwall LGE
55 (35)
Right bundle-branch
block
ST depression
6 (10)
8 (8)
0.78
T-wave inversion
22 (36)
17 (18)
0.01
Ventricular ectopy
8 (13)
22 (23)
0.15
Table 1: Baseline Cohort Characteristics. Data are n
(%) or mean (SD). ACEi = angiotensin-converting
enzyme inhibitor; DCM = dilated cardiomyopathy; EDVi
= indexed end-diastolic volume; EF = ejection fraction;
ESVi = indexed end-systolic volume; LGE = late
gadolinium enhancement; LV = left ventricular; NYHA =
New York Heart Association
Although a small but substantial minority of patients with DCM (17%) had a normal
ECG, they had a less severe DCM phenotype.
Acknowledgements
Table 2: ECG Findings. Data are n (%).
*Left ventricular hypertrophy was defined by Sokolow-Lyon
criteria.6
ECG Abnormality
CMR dimensions and function
(A)
ECG Finding
The two most common ECG abnormalities in our cohort were left bundle-branch block
(25%) and T-wave inversion (20%).
Table 3: ECG abnormalities of patients with severe vs.
mild/moderate systolic impairment. Data are n (%).
Severe LV systolic impairment was defined by an ejection
fraction (EF) ≤35%. P value derived by Fisher’s exact test.
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Conflicts of Interests
None to declare.