Digestive angiodysplasia (or angiectasia, or arteriovenous malformations) is a frequent
digestive finding. Three to 6 % of colonoscopies are performed for reasons other than
bleeding, 25 % when systematic analysis of right hemicolectomy is performed [1]
[2] On the other hand, colonic angiectasia almost never bleeds when discovered by chance,
and is an uncommon cause of lower digestive bleeding [3].
Interestingly the natural history of bleeding from colonic angiectasia is that of
a spontaneous bleeding cessation in more than half of patients during follow-up [4]. The same situation exists for small bowel angiodysplasia, so that the effectiveness
of any therapeutic drug or endoscopic treatment is relatively difficult to demonstrate.
For example, after a first very positive crossover study, estrogen proved to be clearly
ineffective [5] In contrast to drug therapy, the clinical efficacy of endoscopic therapy for angiodysplasia
has never been evaluated in a randomized placebo-controlled study, but only through
(prospective or retrospective) cohorts, thus leaving significant room for doubt about
its efficacy, given the natural history of bleeding angiectasia. This is the case
not only with colonic angiectasia, which had an 89 % bleeding cessation rate 18 months
after argon plasma coagulation (APC) in one large retrospective series, [6] but also with small bowel angiectasia after endoscopic (usually also APC) treatment.
In retrospective series, rebleeding rates of 42 % to 56 % have been seen at 55 months
and 2 years, respectively [7]
[8]. Therefore, the evidence base is far from demonstrating any clear benefit for endoscopic
treatment of bleeding digestive angiectasia. Still, most gastroenterologists are convinced
that endoscopic treatment is mandatory in patients with anemia or overt bleeding from
digestive angiectasia.
Given the lack of prospective demonstration of any benefit of endoscopic treatment,
are there physiological data to clarify the efficacy of these treatment approaches?
Nd-Yag Laser has long been the most-evaluated treatment for vascular digestive lesions
but is now has been abandonned. Argon plasma coagulation (APC) replaced Nd-Yag in
the early 2000 s, and few physiological studies are available. One evaluation on pig
colonic wall showed a risk of transmural coagulation when prolonged (3 sec) APC application
was used [9]. No histological results with APC for digestive angiectasia have been published,
but risk of complication is estimated at 0.5 % to 2.8 % [6]. Japanese teams have recently proposed use of polidocanol to treat digestive hemangiomas,
with impressive results and no complications in specific series of patients [10]
[11]. Japanese physiological studies have shown that polidocanol injection has two successive
effects: the first early, pressure-related, and resulting in thrombotic effects on
small vessels, and the second late thrombus formation effect secondary to vessel inflammation.
Histology showed that the effects of polidocanol were limited to the submucosal layer
[12]. Polidocanol injection has been used for a long time in a large number of patients
and proven to be safe. But a few old case reports, in a very specific situation (deep
duodenal ulcer and treatment with large volume polidocanol) reported some risk of
polidocanol that may be related to digestive perforation [13]. On the other hand, extended experience proved this treatment to be safe in several
randomized trials for prevention of ulcer bleeding [14].
As stated by the authors of this paper, digestive angiodysplasia is anatomically composed
of a dilated submucosal vein associated with a mucosal arteriovenous malformation.
Thus, superficial treatment of the mucosal part of angiodysplasia may explain the
lack of clear efficacy of usual endoscopic treatments like APC [15]
[16].
The new therapeutic protocol described by Tai et al clearly responds to the physiology
of digestive angiodysplasia, by facilitating efficient treatment of the responsible
submucosal vessels. This approach is very innovative, appears feasible from the six
reported cases, and seems efficient as far as can be ascertained from a six-case series
with short follow-up. Will this treatment prove more efficient than previous ones?
Possibly, but prospective series are needed and, as discussed above, at least some
with randomization to alternative treatments. Might this treatment be safer than previous
ones like APC or polidocanol? That absolutely needs to be demonstrated in prospective
randomized studies. Indeed, there is a large published experience with forceps-coagulation,
mainly in treatment of diminutive polyps, and the rate of complication is well established
at 0.5 % (bleeding and perforation) [17]. For these reasons, this approach for diminutive polyps is usually contraindicated
nowadays. Use of this hemostatic technique in a large series of patients with colonic
(or extra-colonic) angiectasia will certainly show some significant risks.
Bleeding from digestive angiectasia is a frequent clinical problem, especially for
teams dealing with capsule endoscopy and enteroscopy. The efficiency of different
available endoscopic treatments for it, however, has been very poorly evaluated. It
is really time to promote some large, prospective, randomized studies comparing these
treatments with simple medical management to clarify the optimal risk:benefit approach
for patients with angiodysplasia.
