Cox Proportional Regression Testing
Multivariable Cox proportional regression analysis was performed to
assess predictors of arrhythmia recurrence yielding hazard ratios with
95% confidence intervals. Predictors of AF recurrence noted in Kece et.
Al. were tested in a univariate model. Subsequently variables with P
values ≤0.05 were included in the multivariate analysis using the
“enter” method in The R Project.
Results :
Patient Characteristics :
Baseline characteristics of the analyzed patients are listed in Table 1.
Within this cohort of 110 patients, 57 had complete voltage mapping of
the entire LA surface area. The median LAPW lesion density was 38%.
Comparison of baseline characteristics of patients stratified by median
LAPW lesion density revealed no significant differences between groups
(Table 1).
Lesion Density :
The method of LAPW lesion density calculation is shown in Figure 1. LAPW
lesion density ranged from 0 - 99% (Figures 2-3). When the cohort was
stratified by median LAPW lesion density there was no significant
difference in arrhythmia recurrence between groups (31% vs. 27%,
p=0.8; Figure 4a). The same was true for AT-free recurrence (20% vs.
13%, p=0.4; Figure 4b). In the 69/110 patients where complete LA
voltage mapping, there was no relationship between the proportion of
posterior wall scar burden and ablation lesion density within the LAPW
(Figure 5).
Electrically Isolated LA Surface Area :
The proportion of electrically isolated LA surface area ranged from
35-75%. Patients with greater LA scar burden also had lesion sets with
larger proportions of electrically isolated LA (Figure 10). In order to
more granularly assess the effect LAPW size on arrhythmia recurrence,
the cohort was stratified by median proportion of electrically isolated
LA surface area, there was no significant difference in arrhythmia
recurrence (31% vs. 27%, p=0.8; Figure 6). However, when the cohort
was subdivided into quartiles by total LA surface area, there was
significantly decreased arrhythmia-free survival in the top quartile
compared to the bottom quartile (48% vs. 22%, p=0.02; Figure 7).
LA Scar Burden :
LA Scar burden ranged from 1-80% in the 57/110 patients for which it
was mapped. There was no difference in arrhythmia-free survival noted
between the top and bottom halves of this subgroup when sorted by median
scar burden (29% vs. 28%, p=1; Figure 8). There was also no difference
in arrhythmia recurrence between those patients who underwent voltage
mapping and those who did not undergo voltage mapping (30% vs. 28%,
respectively, p=0.5; Figure 9).
Cox Proportional Regression Analysis :
In the univariate analysis, increasing patient age, ejection fraction,
and WACA area were associated with increased rates of AF/AT recurrence;
increasing LA area was slightly negatively associated with AF/AT
recurrence (Table 2).