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Oral angioedema secondary to ACE inhibitors, a frequently
overlooked association: case report and review
Miriam Hurst, Marianne Empson
Angioedema is a common problem; in clinical practice it is
usually either idiopathic or secondary to allergens or medications. Angiotensin
converting enzyme (ACE) inhibitors and nonsteroidal anti-inflammatory
medications (NSAIDs) are the most common medications responsible for angioedema.
ACE inhibitor-induced angioedema can occur at any stage of treatment and is
potentially life-threatening. However, this condition is under-recognised, and
many patients who present to immunology outpatients clinics with typical
histories of ACE inhibitor-induced angioedema are still receiving these
medications. We present an illustrative case of ACE inhibitor-induced angioedema
from Auckland, New Zealand, followed by a discussion aimed at helping doctors
recognise and manage this association.
Case reportA 71-year-old European woman was referred to Auckland City
Hospital’s Immunology Clinic for
investigation of angioedema. Some months earlier, she woke with tongue swelling
that impaired her speech and made breathing difficult. An ambulance was called
and she received three doses of intramuscular adrenaline but with no
improvement.
At the emergency department she was given nebulised
adrenaline, steroids, and antihistamines, with gradual resolution of her
symptoms, and she was observed in intensive care overnight. She was discharged
with a prescription for an EpiPen® (a self-injecting adrenaline device, DEY
L.P., Napa, California); no other changes were made to her medication.
She also reported three milder episodes of angioedema over
the preceding 2 years, one episode affecting the tongue and the other two her
cheeks. No other triggers had been identified. She had been diagnosed with
hypertension 3 years previously and started on cilazapril 5 mg once daily and
pindolol 15 mg once daily. Other medical problems included a history of
osteoarthritis, osteoporosis, eczema, and hay fever. She had no history of food
or drug allergies.
ACE inhibitor-induced angioedema was thought to be the most
likely diagnosis for all her episodes of angioedema. Her beta-blocker therapy
could have contributed to the severity of her reaction and lack of response to
adrenaline. This diagnosis was discussed with her GP and arrangements were made
for her to alter her current antihypertensive medications under his
guidance.
The patient was informed of her diagnosis and its
implications, and instructed in the use of her EpiPen.
Causes of angioedemaAngioedema is a nonpitting oedema involving deeper layers of
the cutaneous and mucosal tissues caused by allergic or nonallergic
reactions.1,2 Although any part of the body may be affected, the commonest sites
for skin involvement are the perioral and periorbital tissues.2 Angioedema
involving the tongue and throat can be fatal due to asphyxia.1 Gastrointestinal
angioedema may present with abdominal pain, nausea, and diarrhoea; other organ
systems are rarely affected.1
A good clinical history is essential in establishing the
diagnosis and determining possible causes. Factors to consider include timing
and duration of the episode(s), particularly in relation to any possible
triggers such as foods or environmental stresses (e.g. heat, cold, exercise).
Drug history, especially new medications or over the counter agents such as
NSAIDs, is also important, as are any associated symptoms (such as urticaria),
other diseases (autoimmune or atopic), and family history.
Angioedema can be part of an IgE-mediated allergic reaction
(most commonly to foods such as peanuts, tree nuts, or shellfish; or medications
such as penicillin) or non-allergic as with ACE inhibitors, most NSAID
reactions, and chronic idiopathic urticaria/angioedema.3 Rare causes include
congenital or acquired deficiencies in C1 esterase inhibitor (C1-INH).2 Most
cases of angioedema in adult clinical practice are not IgE-mediated—a
significant proportion of cases are due to ACE inhibitors.
ACE inhibitors in clinical practiceACE inhibitors are used widely in New Zealand. According to
New Zealand’s drug-buying agency, PHARMAC, in the year ending June 2004,
just over 1 million prescriptions were filled for ACE inhibitors (value
estimated from graph).4 The main clinical indication for ACE inhibitors is
hypertension; however, ACE inhibitors are also used to treat congestive heart
failure and diabetic nephropathy, and to significantly decrease morbidity and
mortality after myocardial infarction.5
Adverse effectsACE inhibitors are generally well tolerated. Significant
adverse effects include hypotension, renal impairment, and cough. Cough is a
side-effect specific to ACE inhibitors, reported in 5 to 20% of patients; it is
thought to result from bradykinin and/or prostaglandin accumulation.6
Angioedema is a less common reaction that has been
associated with all ACE inhibitors. Most ACE inhibitor-induced angioedema
involves the tongue, pharynx, or perioral tissues. No diagnostic test exists at
present; the diagnosis is made on the classical history and ingestion of the ACE
inhibitor. Visceral angioedema with ACE inhibitors is rare, but has been
reported, and needs to be considered in the context of recurrent abdominal pain
where no other cause has been identified.7
ACE inhibitors and angioedemaIncidence—Initial
estimates of the incidence of angioedema during ACE inhibitor treatment were
around 0.1%,6 although rates of up to 2% have subsequently been observed.8
Observational studies suggest a rate of 0.1% per year of treatment, resulting in
an overall risk of up to 1% after 10 years of treatment.1 The majority of
reactions are in the first week of treatment but they can occur at any time; in
addition, episodes of angioedema have been reported after stopping ACE inhibitor
treatment.1 Although these episodes are predominantly in the first month after
treatment cessation, we have observed episodes up to 3 months afterwards.
People with a history of idiopathic angioedema are at an
increased risk of ACE inhibitor-induced angioedema.6 For unknown reasons,
studies indicate a higher incidence in African-Americans (4.5-fold more that in
white Americans).9 There are no Maori or Pacific Island data. Episodes of
angioedema may also be triggered by trauma, such as intubation or endoscopy.10
Patients experiencing ACE inhibitor-associated cough are not significantly more
likely to develop ACE inhibitor-associated angioedema.
One case series indicated that ACE inhibitor-associated
angioedema may account for up to 40% of all angioedema presentations to the
emergency department.11 Despite this, the role of ACE inhibitors may be
overlooked. In one study, patients presenting with recurrent angioedema while
taking ACE inhibitors had their ACE inhibitors stopped on only 3 of 14
occasions;12 in another series of 6 patients with ACE inhibitor-associated
angioedema who presented on 9 occasions, ACE inhibitors were identified as a
possible cause only once.13 Our clinical experience also suggests that a
significant number of patients referred to us for investigation of angioedema
are still on ACE inhibitors at the time of referral.
Severity—Studies
suggest hospitalisation for ACE inhibitor-induced angioedema patients was
necessary in roughly half of all cases.12,14 Intubation or tracheostomy was
required in 5–16% of hospitalised patients12,14,15 and 4 deaths were
reported in one early study, although 2 were thought to be unrelated to ACE
inhibitor usage.14 In a United States study, a coroner’s review of 2000
autopsies from 1998 to 2000 found 7 deaths from ACE inhibitor-induced angioedema
of the tongue, all in African Americans aged 51 to 65 years.16
Failure to identify ACE inhibitors as a cause and cease
treatment may be associated with increasing severity of the reaction. In one
study of 82 patients with ACE inhibitor-induced angioedema, 45% required
hospitalisation for their initial presentation with angioedema; however, 64%
required hospitalisation for recurrent reactions, and rates of intubation also
increased from 5% to 18%.12
Proposed
mechanisms—The exact mechanism of ACE inhibitor-associated
angioedema is not yet certain. Immunological and complement-based mechanisms are
thought to be unlikely, as there is no increase in IgE levels and a lack of
other allergic phenomena. Significant complement or C1-INH deficiencies have not
been demonstrated. Current theories focus on the effects of the ACE inhibitor on
the renin-angiotensin-aldosterone system.
Normally, ACE converts angiotensin I to angiotensin II
(ATII); see Figure 1. It also catalyses the breakdown of bradykinin and other
vasoactive substances such as substance P.1 Blocking ACE with an ACE inhibitor
decreases levels of ATII and increases levels of bradykinin, a vasoactive
peptide which acts on a constitutively-expressed B2 receptor (found on smooth
muscle and vascular endothelium) to cause vasodilation and increased vascular
permeability. The increase in bradykinin is thought to be responsible for the
angioedema seen in ACE inhibitor-induced angioedema.
Figure 1. The renin-angiotensin-bradykinin system and
sites of drug action
ACE=Angiotensin converting
enzyme, AT-II=Angiotensin II receptor blocker, BK=Bradykinin.
Some studies have shown increased levels of bradykinin in
patients with ACE-induced angioedema versus controls; however, patients with ACE
dysfunction do not have increased rates of angioedema.1 Acute external trauma
can increase concentrations of vasoactive substances and may be responsible for
the connection between intubation and angioedema.1
In addition to being metabolised by ACE, bradykinin is also
metabolised by the specific peptidases aminopeptidase P, carboxypeptidase N, and
dipeptidyl peptidase IV (DPPIV).18,19 Studies in small numbers of patients have
shown lower levels of carboxypeptidase N,19 aminopeptidase P,19 or DPPIV18,20 in
patients experiencing ACE inhibitor-induced angioedema, compared with controls;
however, results have not been consistent across all studies.
Management of ACE inhibitor-induced angioedemaAcute
attack—Angioedema sparing the airway can usually be managed
conservatively with antihistamines with or without steroids and discontinuation
of the causative medication. However, when the tongue and upper airway are
involved, intramuscular adrenaline should be used (although its efficacy is
uncertain as there are no controlled trials) and some patients may even require
an artificial airway (e.g. intubation or cricothyroidectomy).
Fresh frozen plasma has been successfully used in treating
patients with severe ACE inhibitor-induced angioedema that has not responded to
other treatments.21,22 C1 esterase inhibitor concentrate has also been used
successfully in one case,23 although the reason for this is uncertain, as
patients with ACE inhibitor-induced angioedema have normal C1 esterase inhibitor
levels.
Long term—ACE
inhibitor-induced angioedema is a class effect, so patients experiencing
angioedema with a particular ACE inhibitor should not be switched to another ACE
inhibitor.1,6 Calcium channel blockers and/or thiazides are appropriate as
alternative antihypertensives. Beta blockers are contraindicated in the initial
setting because of the risk of recurrent episodes and their antagonistic effects
on adrenaline; however, they could be used once it has been established that the
angioedema has not recurred after stopping the ACE inhibitor. Generally an
interval of at least 6 months would be recommended to exclude the possibility of
idiopathic or non-ACE inhibitor-related causes of angioedema.
Patients with other causes of angioedema may have their
episodes exacerbated by concurrent ACE inhibitor usage so these should still be
avoided in these patients.
Patients with a history of laryngeal oedema or
life-threatening reactions should be given an EpiPen in case of recurrence and a
MedicAlert® bracelet should be considered.
Alternative medications:
are AT II receptor blockers safe?—ATII receptor blockers have been
used as alternatives to ACE inhibitors in patients unable to tolerate these
drugs because of cough.8 However, literature reviews indicate several cases of
angioedema associated with ATII receptor blockers,8,24,25 with at least one case
requiring emergency tracheotomy,25 although the overall incidence appears lower
than that with ACE inhibitors. There is a predominance of cases associated with
losartan, although this may represent prescribing bias.
In one paper, 6 of 19 patients with angioedema associated
with ATII blockers had previous histories of ACE inhibitor-associated
angioedema,24 hence suggesting that ATII blockers may not be an acceptable
alternative to ACE inhibitors in patients with ACE inhibitor-induced angioedema.
A recent retrospective review of 64 consecutive patients
with ACE inhibitor-related angioedema found that 2 of the 26 patients commenced
on an ATII blocker had further angioedema secondary to the ATII blocker.26 The
potential benefits of the ATII blocker need to be considered against the risks
of further angioedema when deciding whether a trial of these medications is
warranted.
The futureUsage of ACE inhibitors is likely to increase and
consequently the number of patients experiencing ACE inhibitor-induced
angioedema will also increase. Observational studies indicate that ACE
inhibitors are currently significantly under-prescribed in certain patient
populations, such as those who have experienced acute myocardial infarctions.5
Combination therapy with both ACE inhibitors and ATII blockers has been
suggested in patients with diabetic nephropathy as a way to limit proteinuria
and delay (or prevent) disease progression;27 it is not clear how common
angioedema will be with this combination.
Newer agents currently in development for treatment of
hypertension and/or heart failure include omapatrilat, which inhibits both ACE
and neutral peptidases; rates of angioedema with this medication are currently
unknown.28 However, if the pathogenesis of ACE inhibitor-induced angioedema can
be identified, it may be possible to screen patients before treatment and
identify those at higher risk of this significant complication.29
New agents such as icatibant30(a selective bradykinin
receptor B2 antagonist) and DX-8831 (a kallikrein inhibitor) are currently in
clinical trials for the treatment of acute attacks of hereditary angioedema, and
may in the future have a role to play in the treatment of ACE inhibitor-induced
angioedema.
Author information:
Miriam Hurst, Immunology Registrar, Clinical Immunology Department, Liverpool
Hospital, Sydney, NSW, Australia; Marianne Empson, Clinical Immunologist,
Auckland City Hospital, Auckland
Correspondence:
Marianne Empson, Clinical Director Immunology, Level 6 Support Building,
Auckland City Hospital, Private Bag 92024, Auckland 1001. Fax: (09) 307 4998;
email: MarianneE@adhb.govt.nz
References:
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