Discussion
Clinical Characteristics in Patients with PVCs from the MA: We
demonstrated that although the differences were not significant between
the two groups, the mean patient age, serum creatinine, and prevalence
of hypertension were slightly older and higher in the Higher group than
Lower group. Hypertension causing a pressure overload of the LV and
aging contributing to myocardial degeneration may have affected the
increase in the MA-PVCs. The prevalence of no medication (43% versus
0%; p = 0.030) in the Lower group was higher than that in the Higher
group. The family doctors may have tended to prescribe antiarrhythmic
agents to the patients with a higher frequency of PVCs.
Clinical Benefits of RFCA of MA-PVCs: This retrospective study
provided evidence in support of the concept that some patients with
frequent MA-PVCs of more than 20% of the total heart beats, without any
overt underlying structural heart disease, were associated with LV
dilation, which is known to be a risk factor for LV dysfunction and
congestive heart
failure3. Before the
RFCA, the parameters including the LVEF, LVDd, LVDs, NYHA functional
class, and serum BNP concentration, in those higher PVC-patients (20%
<) were worse than in the lower PVC-patients (≤ 20%) (Figure
2ABCD, Table 2). Those abnormalities were still present one day after a
successful RFCA. Furthermore, those parameters in the patient with an
unsuccessful RFCA still deteriorated further during the follow-up. Those
findings may have indicated that the frequent MA-PVCs of more than 20%
of the total heart beats, may be an important and independent risk
factor for the progression of LV dysfunction and heart failure. The
findings of an elevated serum BNP concentration (Table 2) before the
RFCA may also support the possibility of heart failure progression. More
importantly, ablating the MA-PVCs readily produced an improvement in
those abnormalities without any adverse effects. Attenuation of the
progression of the LV dilation has been proven to reduce the risk of
cardiovascular events3,
and RFCA is known to be safe and effective for the treatment of
arrhythmias as compared to medical
therapy1,
2. Thus, RFCA may be considered as the
first choice of therapy in patients with frequent MA-PVCs.
RFCA of MA-PVCs : A recent report demonstrated that in 18 of 21
patients (86%) a successful ablation could be achieved in those with
MA-PVCs/VT7. Procedural
success was achieved in 20 (91%) of the 22 patients, which was slightly
higher than that of the previous
report7. In order to
achieve a high procedural successful rate, we tried and paid attention
to the 3 points described below. (1) First, to gain a strong support and
contact force of the ablation catheter, the trans-interatrial septal
approach was initially performed and a steerable introducer
(AgilisTM NxT, Abbott, Plymouth, Minn, USA) was
routinely used. Actually, of those 20 patients with a successful
procedure, in 19 (95%) a successful RFCA of the MA-PVCs could be
achieved with the trans-interatrial septal approach on the ventricular
side of the MA from the supra-mitral valve (59%) (Figure 3B) and
infra-mitral valve (9%) (Figure 3C) and on the LA side of the MA (18%)
(Figure 3D) (Table 3). Interestingly, in 4 patients (18%) a successful
RFCA was achieved on the LA side of the MA using the trans-interatrial
septal approach (Figure 3D). Thus, operators should try to ablate
MA-PVCs on the LA side of the MA (Figure 3D), when those PVCs cannot be
ablate on the ventricular side of the MA (Figure 3BC). It may be hard
for the ablation catheter to reach the LA using the trans-aortic
approach (Figure 3E). Moreover, in the remaining 2 patients (9%) with
an unsuccessful procedure, successful results could not be achieved even
though a trans-aortic approach was additionally performed8 (Figure 3F). The
trans-aortic approach was not considered to be able to gain a stronger
support and contact force than the trans-interatrial septal approach.
Further, the remaining 1 patient (5%) underwent a successful procedure
that could be achieved from a coronary sinus
approach6,
8 Thus, a right-sided approach including
a trans-interatrial septal and coronary sinus approach may be considered
first, when MA-PVCs need to be ablated. (2) Second, to detect more
precise earliest activation sites of culprit MA-PVCs, electro-anatomical
mapping was performed in detail using a circular mapping catheter
(InquiryTM AFocusIITM Double Loop
Catheter, St. Jude Medical, St. Paul, MN, USA) or high density mapping
catheter (AdvisorTM HD Grid catheter, Abbott,
Plymouth, Minn, USA) on the both LV and LA side of MA. (3) Third, to
obtain a stable lesion creation, an open irrigated 3.5-mm-tip ablation
catheter (FlexAbilityTM, St. Jude Medical, St. Paul,
MN, USA) was routinely used. However, unfortunately, in 2 patients (5%)
successful results could not be achieved even though RFCA using open
irrigated ablation catheters from the various approach sites described
in Figure 3B-F was performed. The recent advancements in the new
technologies, including contact force
catheters9, which can
facilitated a more stable lesion creation, were not used in this study,
and they might have improved and helped during the RFCA procedure in
those unsuccessful patients using open irrigated ablation catheters.
Distribution of the Earliest Activation Sites of the MA-PVCs :
The earliest activation sites of the MA-PVCs were crowded in the
direction from 0:00 to 3:00 in the left anterior oblique view of the MA
(Figure 3G) where the left atrial appendage was attached. Although
there has been a case report supporting a
possible association between ventricular arrhythmias and the LA
appendage10, the
detailed mechanism (s) of MA-PVCs still remain unidentified.
Treatment of patients with an unsuccessful RFCA. Of the 22
patients, in 2 in the Lower group the procedure was unsuccessful during
this study. All of the parameters including the %PVC, NYHA functional
class, serum BNP concentration, and LVDd, LVDs, and LVEF obtained by the
echocardiogram, in the 2 patients with an unsuccessful RFCA still
deteriorated further during the follow-up (Table 1-3, Figure 2B-F).
Thus, intensive treatment of heart failure including the administration
of renin-angiotensin system inhibitors and diuretics was started after
the unsuccessful RFCA, resulting in a comparative improvement in the
patient symptoms. The class I agents were discontinued because of the
adverse effects of the long-term antiarrhythmic medications associated
with those agents such as an increased mortality, probably due to their
proarrhythmic effects, even though the occurrence of the PVCs was
markedly suppressed11.
Comparison of the PVCs from the MA,
RVOT1, and near the
His-bundle2 : This study
has demonstrated that MA-PVCs were common in males in their 60s, and the
QRS duration was wide (142 ± 28 ms) and caused LV dilation. We
previously showed that
RVOT-PVCs1 were common
in females in their 50s, and the QRS duration was wide (141 ± 25 ms) and
caused LV dilation, and PVCs from near the His-bundle
(His-PVCs)2 were common
in males in their 70s, and the QRS duration was narrow (119 ± 23 ms) and
did not cause LV dilation. We also previously reported that frequent
RVOT-PVCs (20% <) increased MR, and eliminating those PVCs
produces an improvement in the
MR1, but not the
frequent MA-PVCs (20%) in this study. RVOT-PVCs cause left branch
bundle block (LBBB), which causes a dyssynchronous myocardial
activation, which progresses into
MR12. On the other
hand, the MA-PVCs caused RBBB, which may not have a great enough effect
on the dyssynchronous myocardial activation. Thus, although the clinical
background differed in the patients with those MA-, RVOT, and His-PVCs,
frequent (20% <) PVCs with a wider QRS duration may be one of
the important predictors of LV dilation.