Download The electrocardiogram in heart failure

q 2000, British Geriatrics Society
Age and Ageing 2000; 29: 203–206
REVIEW
The electrocardiogram in heart failure
JAMES KELLY, KEVIN KELLEHER
Department of Elderly Medicine, Queen Mary’s Hospital, Sidcup, Kent DA14 6LT, UK
Address correspondence to: J. Kelly. Fax: (+44) 1932 867811
Keywords: electrocardiogram, heart failure
Introduction
Heart failure is predominantly a disease of older people,
affecting almost 1 in 10 of those over the age of 80 [1]
and accounting for 5% of hospital admissions in this age
group [2]. Although an overall 5-year survival figure of
50% has been quoted [3], prognosis is considerably
worse in older patients, with a corresponding figure of
less than 20% in those aged 80 or over [4].
Angiotensin-converting enzyme inhibitors [5] and
b-blockers [6, 7] reduce morbidity, mortality and
hospitalization rates in patients with systolic heart
with benefits in older (>60) as well as younger subgroups [5, 8], although very elderly patients have
generally been under-represented in these trials. More
recently, spironolactone has been shown to reduce
morbidity and mortality in patients with advanced
systolic heart failure when added to standard treatment, an effect seen in the older as well as the younger
subgroups within the trial [9].
Diagnosis of heart failure in older people
Given these important prognostic and therapeutic
implications, correct diagnosis of heart failure is
essential. However, diagnosis may be difficult, particularly in older patients, for a number of reasons.
First, older people are more likely to present with
atypical symptoms (such as cough, weakness or
confusion) and the specificity of more classical
symptoms is reduced by inactivity and co-morbidity
[10].
Secondly, there may be over-reliance on isolated
physical signs, such as ankle oedema and pulmonary
crepitations, which lack sensitivity and specificity and
may be misleading, although they may be more useful
in combination [10, 11]. In one study of 207 patients
with an average age of 77, pulmonary crepitations were
found to be an insensitive and non-specific sign, with
no cause found for their presence in 42% of patients
[12]. In another study of patients presenting to hospital
with acute dyspnoea, isolated crepitations were found
to be a poor predictor of left ventricular systolic impairment [13]. Anecdotally, it is common to find diuretics
initiated in elderly patients on the basis of basal
crepitations alone, even in the absence of a radiological
correlate of pulmonary oedema.
Thirdly, although all patients with suspected heart
failure should ideally undergo transthoracic echocardiography [14, 15], many do not do so as demand for
this resource continues to exceed supply. In one audit
in primary care, only 31% of patients with a clinical
diagnosis of heart failure had undergone echocardiography—even though 75% had been seen at hospital at
some stage [14]. In another study of 307 patients with
heart failure (mean age 82) admitted to 12 different
geriatric units, 40% of whom were newly diagnosed,
echocardiography was performed in only 39% (either
during the index admission or previously [15]).
Fourthly, difficulties arise as there is no agreed
standard for the diagnosis of heart failure. One useful
diagnostic paradigm, however, is that of the Working
Group on Heart Failure of the European Society of
Cardiology. This states that a positive diagnosis of heart
failure requires appropriate symptoms, evidence of
fluid retention (pulmonary or peripheral oedema) and
evidence of a structurally abnormal heart on echocardiography. In doubtful cases, a symptomatic response
to a trial of diuretic is regarded as confirmatory
evidence [16].
Heart failure in older people is therefore both
under- and over-diagnosed [17]. Studies examining the
validity of a primary care diagnosis of heart failure in
patients at a range of ages have shown that specialist
cardiological evaluation (including transthoracic echocardiography) results in rejection of the diagnosis in
half to three-quarters of cases [18–20]. Therefore many
patients are treated inappropriately on the basis of
non-specific signs and symptoms [21]. However,
these studies may overestimate the prevalence of
false positives, as the diagnosis of heart failure was
accepted only if evidence of systolic dysfunction was
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J. Kelly, K. Kelleher
demonstrated on transthoracic echocardiography,
thereby excluding patients with possible diastolic
heart failure. Although an uncommon cause of heart
failure in younger patients, diastolic dysfunction may
account for up to 30–40% of cases of heart failure in
older people [22]. While still associated with substantial morbidity and mortality, it appears to have a more
favourable prognosis than systolic heart failure—but
optimal treatment remains uncertain [22]. On the
other hand, many patients with heart failure remain
untreated. In one study of patients with systolic heart
failure living at home, 30% of those identified were
receiving no treatment [23].
Utility of the electrocardiogram (ECG)
in suspected heart failure
When assessing a patient with possible heart failure,
the utility of the ECG has perhaps been underappreciated. Although performed in most patients
assessed in hospital (but probably only a minority in
primary care [14]), the ECG may receive scant
attention and may not be taken into consideration
when deciding whether or not a patient’s symptoms
are caused by heart failure in the absence of
echocardiographic guidance. The clinician does well
to examine the ECG carefully in this context, as studies
have demonstrated that the diagnosis of systolic heart
failure is unlikely if the ECG is normal.
One of the best known is a study of 96 patients
(aged 17–94) with echocardiographically-proven left
ventricular systolic dysfunction referred from primary
care to an open access echocardiography service.
Major ECG abnormalities (atrial fibrillation, previous
myocardial infarction, left ventricular hypertrophy,
bundle branch block or left axis deviation) were
identified in 90. No patient had a normal ECG [24].
In another study of 71 emergency admissions
presenting with acute dyspnoea (mean age 73), the
37 with proven systolic heart failure all had abnormal
ECGs [13]. In a series of 252 acute admissions with
heart failure (mean age 73), the ECG was abnormal in
every case (although the proportion that had a
transthoracic echocardiography was not stated) [25].
Similarly, of a series of 100 patients (mean age 74)
presenting with acute pulmonary oedema, only one
had a normal ECG. This series included 20 patients
with normal systolic function, half of whom had
valvular disease (including the one patient with a
normal ECG, who had mitral stenosis) as the dominant
substrate for the episode [26]. In a series of 165
patients with ejection fractions of <40% attending a
heart failure clinic (mean age not stated), 89% had an
abnormal ECG [27]. Finally, a cross-sectional study of
1640 patients aged 25–74 was performed to define the
prevalence of left ventricular systolic dysfunction. It
demonstrated an abnormal ECG (defined as Q waves,
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left bundle branch block, ST depression, abnormal T
waves, left ventricular hypertrophy, atrial fibrillation or
flutter) in 77% of those with symptomatic left
ventricular systolic impairment [23].
The ECG is therefore highly sensitive for the
diagnosis of clinical systolic heart failure, particularly
in patients presenting acutely. In the three series
which examined this subgroup [13, 25, 26], the ECG
was abnormal in every case (presumably reflecting
more advanced ventricular disease in these patients).
Although specificity is only low to moderate (an
abnormal ECG is associated with about a one in three
chance of left ventricular systolic impairment [24]),
the presence of Q waves, left ventricular hypertrophy
or an arrhythmia may suggest an underlying cause.
Other ECG signs may occasionally be useful. For
example, the triad of high precordial QRS voltage,
poor precordial R wave progression and low limb lead
voltage is said to have high specificity for the diagnosis
of heart failure [28]. The combination of right axis
deviation and left bundle branch block is highly
suggestive of idiopathic dilated cardiomyopathy [29],
and the combination of right axis deviation and atrial
fibrillation is suggestive of mitral stenosis, although it
may be seen in other situations [30].
This impressive sensitivity is particularly useful
given the known high false-positive rates in the
diagnosis of heart failure [18–20], as a normal ECG in
the context of suspected heart failure suggests either
that the diagnosis is incorrect and other possibilities
should be pursued [16, 24, 31, 32] or, if clinical
suspicion remains strong, that valvular disease [24] or
an uncommon condition such as pericardial disease
may be the cause [31].
In the acute situation or at first presentation,
assimilation of information from the ECG with clinical
findings increases the specificity of diagnosis of heart
failure [13]. Greater attention to the ECG in combination with historical, clinical and radiological factors
could potentially reduce the number of false-positive
diagnoses, particularly when transthoracic echocardiography may not be immediately available. This would
reduce the number of patients receiving inappropriate
treatment with diuretics, the commonest cause of
adverse drug reactions in the older population [33].
In addition, the clinician should always examine the
ECG in patients with apparent established heart failure
where the diagnosis has been made and treatment
initiated without echocardiographic guidance by a nonspecialist. Again, a normal ECG in this context should
lead to a re-evaluation of the diagnosis and request for
transthoracic echocardiography. Where left ventricular
function is found to be normal, withdrawal of heart
failure treatment should be considered. However, some
of these patients may have diastolic dysfunction. It may
therefore be prudent to review the clinical context in
which the diagnosis of heart failure was made before
discontinuing diuretics. If doubt remains, the physician
The electrocardiogram in heart failure
should request a further echocardiographic examination, and consider specialist referral, looking specifically for diastolic dysfunction [34].
converting enzyme inhibitors on mortality and morbidity in patients
with heart failure. JAMA 1995; 273: 1450–6.
Conclusion
7. MERIT–HF study group. Effect of metoprolol CR/XL in chronic
heart failure: metoprolol CR/XL randomised intervention trial in
congestive heart failure (MERIT–HF). Lancet 1999; 353: 2001–7.
The ECG has high sensitivity for the diagnosis of
systolic heart failure and is undervalued in this regard.
Its sensitivity in diastolic heart failure has not been
studied. In patients assessed for the first time, a normal
ECG suggests that alternative diagnoses should be
pursued—unless a murmur is present or clinical
suspicion is otherwise strong. In patients already
established on heart failure treatment without prior
echocardiographic guidance, a normal ECG should
lead to a reassessment of the diagnosis and a request for
echocardiography. Although a normal ECG in this
context will only identify a few inappropriately treated
patients (clearly, some patients with a false-positive
diagnosis of heart failure will have abnormal ECGs), it
will, nevertheless, identify a subgroup of patients in
whom echocardiography is likely to lead to an
important change in treatment.
With the continuing imbalance between supply and
demand for echocardiography services in many districts, a greater awareness of the importance of the
ECG in patients with suspected heart failure could
reduce the proportion treated inappropriately. A
normal ECG in this context is arguably one of the
most underused signs in clinical medicine.
Key points
• Systolic heart failure is unlikely in the presence of a
normal ECG.
• The ECG is a useful, and probably undervalued,
diagnostic aid when access to echocardiography is
limited.
• Where heart failure has been confirmed, the ECG
may suggest an aetiology.
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