Statistical analysis
Categorical data are represented as proportions, continuous data as mean
± SD for normally distributed variables or median and interquartile
range for non-normal distribution. Comparisons were made using
Chi-Square Test, Fisher’s exact test, unpaired student T-test and
Mann-Whitney test. Multivariable COX proportional hazard models were
used to identify independent characteristics and medical treatment
associated with VA or mortality. To assess the impact of VA on overall
mortality a Cox model with time to first VA as a time dependent
covariate was used. Unadjusted and adjusted Hazard ratios (HRs) with
95% confidence intervals (CIs) were displayed. All tests were two
sided, p-values < 0.05 were considered statistically
significant. Analyses were carried out using IBM SPSS Statistics for
Windows, Version 25.0. Armonk, NY.
Results
There were 186 patients implanted with an ICD/CRTD between the years
2007-2017 that matched the study’s inclusion criteria (Figure 1). Their
mean age was 66.4±12 years, 15.1% were female. ICD was implanted in 79
(42.5%) and a CRTD in 107 (57.5%). Median [IQR] follow-up time was
3.8 [2.1-6.7] years. Patient characteristics are shown in table 1.
There were 52 (28%) patients with VA, including VT in 31/52 patients
(59.5%), VF in 6/52 patients (11.5%) or both in 15/52 patients (29%).
These VA cases were treated successfully by anti-tachycardia pacing
(ATP) in 22 (42.4%) patients and by device shock in 30 patients
(57.6%). There were 77 (41.4%) deaths during the study F/U period. The
prevalence of HF medication treatment at index hospitalization discharge
was: 155/186 (83.3%) BB, 162/186 (87.1%) AngA, and 110/186 (59.1%)
MRA. AAD were prescribed in 81/186 (43.5%) patients. Doses (% target)
of HF medication were: 32±25% for BB, 38.2±30% for AA and 31±30% for
MRA. The median dose (% target dose) for all 3 guideline-based
medication groups included in our study was 25% (Table 2). Few patients
were prescribed with >50% of target dose: 18/155 (11.6%),
34/162 (21%), and 16/110 (14.5%) of patients taking >50%
target dose of BB, AngA, and MRA, respectively (Table 2).
Only 18/186 (9.7%) of study patients were followed regularly in the
hospital’s HF clinic by HF specialist (most patients were followed
regularly by their general cardiologists and came to our hospital only
for device clinic interrogations). There were more patients treated by
BB among the group followed in HF clinic (100% vs 81.5%, p=0.046) and
their dose (% target dose) was higher (61.1% vs. 33.9%, p=0.023).
There was a non-significant trend for higher prevalence of AngA (88.9%
vs. 86.9%, p=0.81) and MRA (72.2% vs. 57.7%, p=0.23) among those
followed at HF clinic as well.