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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 1, January/February 2021
AFRICA
19
DDDR groups. Sinus pauses/arrest (47% overall in both groups)
and sinus bradycardia (34% overall in both groups) were the
most common ECG manifestations. Sino-atrial exit block and
tachy–brady syndrome were less common.
A comparison of the development of AF, AV block, mortality,
device sepsis and need for lead revision between AAIR and
DDDR pacing is shown in Table 3. Over a median follow up of
5.0 (IQR: 2–11) years, four patients developed AF in the AAIR
group (7.4%) compared to three (4.8%) who developed AF in
the DDDR group (
p
= 0.70). One patient (1.9%) in the AAIR
group developed AF and AV block and required an upgrade to
DDDR pacing. Deaths occurred in 18 (33.3%) patients in the
AAIR group and 14 (22.6%) in the DDDR group. Two (3.7%)
and two (3.2%) patients were lost to follow up in the AAIR
and DDDR groups, respectively. There were no significant
differences between the AAIR and DDDR groups with regard to
mortality, device sepsis or the need for subsequent lead revision.
Six patients needed lead revisions due to lead malposition or
dislodgement (four right atrial and two right ventricular leads).
Discussion
The only effective treatment for symptomatic SND is the
insertion of a permanent pacemaker. The choice of permanent
pacemaker is either an AAIR pacemaker with an atrial lead or
a DDDR pacemaker with atrial and ventricular leads. While
most guidelines recommend DDDR pacing as the first choice
of pacing, AAIR pacing remains an acceptable second choice,
especially in resource-limited settings where the cost of DDDR
pacing is prohibitive. The major disadvantage of AAIR pacing is
the future development of AV block, which requires the addition
of a ventricular lead.
In this study, we report only one case (1.9%) of AV block who
required upgrade to DDDR pacing over a median follow up of
five years. The risk of development of AV block in patients with
SND is reported to be between < 1% and 4.5% per year.
9–13
A
possible reason for the low risk of AV block in our cohort is that
routine functional AV block testing was used in all patients to
decide on the choice of pacemaker. We used a standard pacing
protocol of atrial pacing at the time of implant to determine the
AV Wenkebach rate. All patients received a DDDR pacemaker
if AV Wenkebach or higher-degree AV block was present with
atrial pacing at 120 bpm.
An AV Wenkebach rate lower than 120 bpm was found to be
a predictor of high-grade AV block in a previous retrospective
study comparing AAIR with DDDR pacing and the authors
reported an annual incidence of AV block to be 1.1%.
7
In the
DANPACE trial, the risk of AV block or slow AF occurred in
54 out of 707 patients (7.6%) with an incidence of 1.5% per year.
A lower Wenkebach rate of 100 bpm was used to determine the
need for DDDR pacing in the DANPACE study, which could
explain why the AAIR group had a higher risk of AV block
compared to our study. We propose that AV functional testing
be used to help guide implanters on the choice of pacemaker,
especially in resource-limited environments where the cost of
DDDR pacing is prohibitive.
To evaluate the cost saving of selective AAIR pacing versus
routine DDDR pacing, we compared the total cost of AAIR
and DDDR pacing in this study with a hypothetical scenario
where all patients received DDDR pacing. Using data from
South Africa from the PASCAR 2011–2016 survey,
8
the total
procedural costs of AAIR (US$1 030 per pacemaker) and
DDDR (US$1 380 per pacemaker) pacing for 116 patients
(including one upgrade from AAIR to DDDR pacing) was
estimated to have cost US$142 560. The procedural costs if all
patients received DDDR pacing was estimated to have been
US$160 080. The cost saving therefore amounted to US$17 520.
This equates to a saving of 17 AAIR pacemakers or 12 DDDR
pacemakers in this study.
The DANPACE randomised trial reported a higher rate of
paroxysmal AF, but not chronic AF, in patients who received
AAIR pacing compared to DDDR pacing (heart rate 1.27 with
AAIR pacing,
p
= 0.02)
6
However, extended follow up of the
DANPACE trial reported no differences in AF hospitalisation
between AAIR and DDDR pacing, with an annual incidence
of 1.4%.
15
We report a lower rate and no difference in the
subsequent development of paroxysmal or persistent AF in
both pacing groups (7.4% in the AAIR group compared to 4.8%
in the DDDR group,
p
= 0.70). These findings are similar to a
prior study by Masumoto who also reported no difference in the
development of AF between AAIR and DDDR pacing (6.4%
in the AAIR group compared to 9.4% in the DDDR group at
10 years of follow up).
7
The above data suggest that the choice
Table 2. Electrocardiographic diagnoses of patients who received AAIR
versus DDDR pacing for sinus node dysfunction
ECG description
AAIR (
n
= 54) DDDR (
n
= 62)
p
-value
SND ECG diagnosis,
n
(%)
SND only
44 (81.5)
32 (51.6)
SND + BBB
1 (1.9)
4 (6.5)
SND + AV block
0 (0.0)
15 (24.2)
< 0.001
SND + atrial tachyarrhythmia
9 (16.7)
11 (17.7)
SND ECG categories,
n
(%)
Sinus pauses/arrest
25 (46.3)
29 (46.8)
Sinus bradycardia
20 (37.0)
20 (32.3)
0.700
Sino-atrial exit block
3 (5.6)
2 (3.2)
Tachy–brady syndrome
6 (11.1)
11 (17.7)
AAIR: atrial-pacing atrial-sensing inhibited-response rate-adaptive; DDDR:
dual-pacing dual-sensing dual-response rate-adaptive; SND: sinus node disease;
BBB: bundle branch block.
Table 3. Comparison of mortality and the development of AF,
AV block, device sepsis or lead revision between the AAIR
and DDDR pacing groups
Complication/procedures
Pacing mode
p-
value
AAIR
(
n
= 54, 46.6%)
DDDR
(
n
= 62, 53.4%)
Mortality,
n
(%)
AF,
n
(%)
18 (33.3)
14 (22.6)
0.196
Yes
4 (7.4)
3 (4.8)
0.703
No
50 (92.6)
59 (95.2)
AVB,
n
(%)
Yes
1 (1.9)
1 (1.6)
1.000
No
53 (98.1)
61 (98.4)
Sepsis,
n
(%)
Yes
1 (1.9)
1 (1.6)
1.000
No
53 (98.1)
61 (98.4)
Lead revision,
n
(%)
Yes
4 (7.4)
2 (3.2)
0.415
No
50 (92.6)
60 (96.8)
AAIR: atrial-pacing atrial-sensing inhibited-response rate-adaptive; DDDR:
dual-pacing dual-sensing dual-response rate-adaptive; AF, atrial fibrillation;
AVB: atrio-ventricular block.