The study by Quintella et al.
1
published
in this issue of the journal, brings us valuable information about the use of an
important physiological evaluation tool in the hemodynamic laboratory. FFR-guided
treatment (myocardial fractional flow reserve), used in the percutaneous coronary
intervention (PCI) with bare-metal stent (BMS) implantation in multi-arterial patients
treated in the Unified Health System (SUS) has been shown to be useful in decreasing
the
incidence of new revascularization of the target vessel (clinical restenosis), as
well
as being cost-effective when compared to the angiography-guided treatment.
The value of FFR to predict major adverse cardiovascular events (MCAEs) prior to PCIs
has
been established for many years. Its ability to detect ischemia and, with this, to
guide
the most appropriate treatment, has undergone the test of time, and passed. The 15-year
follow-up of the DEFER
2
study in
single-vessel patients, and the 5-year studies, FAME 1,
3
and FAME 2,
4
in multiarterial patients, showed consistent and unquestionable
results, with a better, or at least similar, clinical progression, in the FFR-guided
groups, using less stents with fewer lesions and consequently lower costs, as well
as
evidenced the safety of leaving lesions whose FFR was not indicative of ischemia only
on
drug treatment.
The limited value of angiography to predict ischemia has long been known. Sant'Anna
et
al.
5
showed a weak correlation
between angiography, expressed as a percentage of stenosis diameter (SD), and FFR
(rho =
- 0.33), especially in intermediate lesions (between 40% and 70%). This disagreement
between SD and physiology has already been documented in several other studies, such
as
that by Toth et al.
6
and Park et
al.,
7
which also showed
disagreement rates between FFR and angiography of 36% and 39% respectively. In a study
published in 2007,
8
in 250 patients
(452 lesions) assessed by FFR before PCI, 32% of the lesions had their initially planned
treatment strategy modified after FFR measurement, which is a major change because
it
would imply inadequate treatment in more than one third of the patients. More recently,
Ciccarelli et al.
9
in a FAME 2
substudy, analyzed the value of angiography compared to FFR to predict the natural
history of coronary lesions, correlating MCAE index with the angiographic and
physiological importance of these lesions in patients (n = 607) who were initially
left
only on drug treatment. In the subgroups in which FFR was discordant of angiography
(FFR
> 0.80 and SD ≥ 50% or FFR ≤ 0.80 and SD < 50%), clinical
progression was worse in those in whom FFR was ≤ 0, 80, even if the lesion was
not significant, and benign in those in whom FFR was > 0.80, regardless of SD.
In the study by Quintella et al.,
1
MCAE
that was reduced in the FFR group was due to the need for new revascularization of
the
target vessel, with no difference in mortality or infarction. Even with the limited
number of patients involved in the study, this data is in agreement with what was
presented in the FAME studies, in which, after 5 years of progression, only the need
for
new revascularization remains different in the groups. We call the attention to the
low
rate of clinical restenosis in the FFR group (5.8%) of the study by Quintella et
al.,
1
because he used only BMS,
which may be due to the fact that much less lesions were treated compared to the angio
group (1.14 vs. 2.22 stents per patient), and with better selection criteria.
Another interesting finding of the study is the cost-effectiveness (CE) relationship,
measured by the incremental cost-effectiveness ratio (ICER), which represents the
ratio
between the costs of technologies under analysis, and their effectiveness. This ratio
is
usually adjusted for quality of life, and expressed as QALY (quality-adjusted life
year). Costs below USD 20,000/QALY are accepted to be highly supportive of the
technology tested. The ICER calculated for the study by Quintella et al.
1
was of R$ 21,156, 55, totally within the
CE criteria, mainly if we consider that only BMS were used, that is, if DES were used,
ICER would be even lower. Fearon et al.
10
have published an interesting study on FFR CE in the population of
FAME 1,
10
in which the author points
out that the FFR-guided strategy has a lower cost compared to that guided by angiography
in 90.74%, and is cost-effective in 99.96% of cases, being one of those rare situations
where a new technology not only improves outcomes, but also saves resources. Siebert
et
al.
11
found similar findings
in the Australian population, where 1.776 USD would also be saved per patient over
1
year with the use of FFR during PCI.
Although we cannot extrapolate these results from other countries to ours, because
the
prices practiced and the reimbursement system are different, we can still assume that
now, when SUS begins to allow the use of drug-eluting stents at a more competitive
price, the strategy of use of FFR becomes even more attractive.