Effect of Cardiac Resynchronization Therapy-Defibrillator Implantation on Health Status in Patients With Mild Versus Moderate Symptoms of Heart Failure




Indications for cardiac resynchronization therapy (CRT) have expanded to include patients with mild congestive heart failure (CHF) symptoms (New York Heart Association [NYHA] functional class II) because of a demonstrated morbidity reduction in this subset of patients. However, little is known about postimplantation changes in their self-reported health status compared to patients with more severe CHF. The aim of this study was to examine the influence of baseline NYHA functional class on health status changes in the first 12 months after implantation of a CRT with defibrillator (CRT-D). Patients with first-time CRT-D (n = 169, 75% men, mean age 62.1 ± 10.7 years) were recruited from 3 Dutch hospitals. All patients completed the SF-36 Health Survey at the time of implantation and at 12 months after implantation. Mildly (NYHA functional class II; n = 54) and moderately (NYHA functional class III; n = 115) symptomatic CHF patients showed improved health status in several SF-36 domains at 12 months after CRT-D. When adjusting for baseline health status, the groups did not differ with respect to their health status improvement over time, but after adjustment for demographic and clinical factors, the mildly symptomatic patients reported relatively more improvement in general health (B = 10.15, SE = 3.31, p = 0.003) and social functioning (B = 10.64, SE = 3.74, p = 0.005). In conclusion, NYHA functional class II patients reported equal, and in some domains even more, improvement in health status compared to NYHA functional class III patients at 12 months after CRT-D. Hence, CRT not only prevents clinical adverse events in patients with mild CHF symptoms but also improves health status.


Besides reducing mortality and morbidity, an important target of treatment in congestive heart failure (CHF) patients is relief of symptoms as well as improvement in health status and quality of life. Several trials have shown that cardiac resynchronization therapy (CRT), often in combination with an implantable cardioverter defibrillator (ICD), leads to improved patient-reported outcomes in patients with moderate to severe (New York Heart Association [NYHA] functional class III or IV) CHF symptoms, but the few available studies on patients with mild (NYHA functional class I or II) CHF symptoms did not demonstrate any health status benefits of CRT with ICD implantation (CRT-D). An explanation could be that mildly symptomatic patients have less room for improvement or that the follow-up time should be longer than the 6 months used in the latter studies to be able to demonstrate a benefit. No study so far has directly compared the health status improvements reported by mildly and moderately symptomatic CHF patients after CRT-D. Hence, the objective of this multicenter prospective study was to examine changes in several health status domains in the first 12 months after CRT-D in patients with mild (NYHA functional class II) versus moderate (NYHA functional class III) CHF symptoms.


Methods


Patients receiving first-time CRT-D from May 2003 to September 2009 at the Erasmus Medical Center (Rotterdam, The Netherlands), the Catharina Hospital (Eindhoven, The Netherlands), and the Amphia Hospital (Breda, The Netherlands) and with NYHA functional class II or III CHF symptoms constituted the patient sample for the present study. Patients included in the Erasmus Medical Center participated in the ongoing Mood and personality as precipitants of arrhythmia in patients with an Implantable cardioverter-Defibrillator: A prospective Study (MIDAS). Exclusion criteria for all hospitals were significant cognitive impairments, a history of psychiatric illness other than affective or anxiety disorders, life expectancy <1 year, NYHA functional class I or IV CHF symptoms, and insufficient knowledge of the Dutch language.


At baseline and at 12-month follow-up, patients were asked to complete a set of standardized and validated questionnaires. The study protocol was approved by the medical ethics committees of the participating hospitals. The study was conducted in accordance with the Declaration of Helsinki, and all patients provided written informed consent.


Demographic variables included gender, age, marital status (single vs having a partner), employment status (currently employed vs unemployed) and educational level (primary schooling or lower vs secondary schooling or higher) and were obtained using purpose-designed questions at baseline. Information on smoking and the use of psychotropic medications was also obtained through purpose-designed questions at baseline. Information on other clinical variables, including cause of heart failure (ischemic vs nonischemic), ICD indication (primary vs secondary prevention), NYHA functional class (II vs III), left ventricular ejection fraction (≤35% vs >35%), QRS duration (<150 vs ≥150 ms), diabetes, and cardiac medications, were extracted from patients’ medical records. Information on the occurrence of shocks (appropriate and inappropriate) during follow-up was obtained by means of device interrogation.


The SF-36 Health Survey was used to assess health status. The SF-36 comprises 36 items, divided into 8 subscales: physical functioning, role physical functioning, bodily pain, general health, social functioning, role emotional functioning, mental health, and vitality. Scores on the subscales are linearly converted into a score between 0 and 100. A higher score on the SF-36 domains represents better functioning; a high score on the bodily pain domain indicates absence of pain. The Dutch version of the SF-36 has been validated in several Dutch populations and has good internal consistency, with a mean Cronbach’s α of 0.84 across all scales. Patients were asked to complete the SF-36 at baseline and at 12 months after implantation.


Discrete variables were compared using chi-square tests and continuous variables (e.g., the baseline health status scores) using Student’s t tests for independent samples. Paired-samples Student’s t tests were used to evaluate intragroup changes in health status scores from baseline to 12 months. To compare the NYHA functional class II and III patients with respect to change in health status in the first 12 months after CRT-D, analyses of covariance were performed, with the absolute change in health status (12-month score − baseline score) as the outcome variable and baseline health status scores as a covariate. Because we expected the health status scores of NYHA functional class II and III patients to differ at time of implantation, we included baseline health status score as a covariate to correct for the phenomenon of regression to the mean. Finally, a set of demographic and clinical variables were included as covariates to adjust for potential confounding. A priori, on the basis of published research, we decided to include age, gender, ICD indication, cause of heart failure, left ventricular ejection fraction, QRS duration, diabetes, psychotropic medications, and ICD shocks. All tests were 2 tailed, and p values ≤0.05 were considered to indicate statistical significance. A Bonferroni correction was applied to adjust for multiple comparisons (p ≤0.006 [α = 0.05/8]). All analyses were performed using SPSS version 17.0 for Windows (SPPS, Inc., Chicago, Illinois).




Results


Information on NYHA functional class was not reported in the medical records for 25 of the 261 patients willing to participate. Of the remaining 236 patients, 14 did not complete the SF-36 at baseline, and 53 patients did not complete the SF-36 at follow-up. The 169 patients eligible for analysis (72%) were on average less likely to have diabetes mellitus (14% vs 27%, p = 0.01) and to have ischemic causes of heart failure (50% vs 69%, p = 0.003), but more likely to use angiotensin-converting enzyme inhibitors (82% vs 71%, p = 0.03), compared to excluded patients (n = 92). No other systematic differences were found between participants and nonparticipants on baseline characteristics.


Baseline characteristics of the total patient sample and stratified by mild CHF symptoms (NYHA functional class II) versus moderate CHF symptoms (NYHA functional class III) are listed in Table 1 . Of the 169 patients, 54 (32%) had mild CHF symptoms at the time of implantation. These patients were more likely to have ICDs for secondary prevention and less likely to use diuretics compared to patients with moderate CHF symptoms. No other statistically significant differences were found between mildly and moderately symptomatic patients on baseline characteristics.



Table 1

Baseline characteristics for the total sample (n = 169) and stratified by mildly versus moderately symptomatic heart failure

































































































































Variable Total (n = 169) NYHA Functional Class p Value
II III
(n = 54) (n = 115)
Age (years) 62 ± 11 62 ± 13 63 ± 10 0.60
Women 42 (25%) 11 (20%) 31 (27%) 0.36
Lower education 36 (21%) 9 (16%) 27 (23%) 0.29
Currently employed 37 (22%) 12 (22%) 25 (22%) 0.97
Having a partner 147 (88%) 46 (85%) 101 (88%) 0.53
Primary prevention indication for ICD 96 (57%) 17 (32%) 56 (49%) 0.04
Ischemic cause of heart failure 84 (50%) 26 (48%) 58 (50%) 0.78
Left ventricular ejection fraction ≤35% 157 (93%) 51 (94%) 106 (92%) 0.31
QRS duration ≥150 ms 115 (69%) 32 (59%) 83 (73%) 0.08
Diabetes mellitus 23 (14%) 5 (9%) 18 (16%) 0.26
Shocks during follow-up 17 (10%) 5 (9%) 12 (10%) 0.81
Smokers 19 (11%) 8 (15%) 11 (10%) 0.32
Amiodarone 34 (20%) 14 (26%) 20 (17%) 0.20
β blockers 144 (85%) 45 (83%) 99 (86%) 0.64
Digoxin 40 (24%) 10 (19%) 30 (26%) 0.28
Statins 101 (60%) 28 (52%) 73 (64%) 0.15
Angiotensin-converting enzyme inhibitors 139 (82%) 42 (78%) 97 (84%) 0.30
Diuretics 137 (81%) 38 (70%) 99 (86%) 0.02
Psychotropic medication 29 (17%) 10 (19%) 19 (17%) 0.73

Data are expressed as mean ± SD or as number (percentage).

Less than secondary school.


p ≤ 0.05.



At baseline, NYHA functional class II patients reported significantly better health status across 3 of 8 domains compared to NYHA functional class III patients: physical functioning (mean 59.02, SE 3.03 vs mean 43.73, SE 2.21; t [167] = 3.98, p <0.001), role physical functioning (mean 38.43, SE 5.64 vs mean 16.30, SE 2.76; t [79.4] = 3.52, p = 0.001), and vitality (mean 55.25, SE 2.47 vs mean 43.42, SE 1.86; t [167] = 3.69, p <0.001). Changes in health status scores across the domains of the SF-36 from baseline to 12-month follow-up are shown in Figure 1 . Paired-samples t tests showed that the NYHA functional class II patients significantly improved across 3 of 8 health status domains: role physical functioning (mean diff 19.91, SE 5.81, t [53] = 3.42, p = 0.001), social functioning (mean diff 16.90, SE 3.19, t [53] = 5.30, p <0.001), and vitality (mean diff 8.89, SE 2.45, t [53] = 3.63, p = 0.001). The NYHA functional class III patients improved in 6 of 8 health status domains, except for role emotional functioning (mean diff = 9.57, SE 4.54, t [114] = 2.11, p = 0.04) and general health (mean diff 0.72, SE 1.97, t [114] = 0.37, p = 0.71).




Figure 1


Changes in health status scores of mildly (NYHA class II) versus moderately (NYHA class III) symptomatic CHF patients. Reported p values represent the significance levels of the intragroup changes in health status (paired Student’s t tests).


To correct for the phenomenon of regression to the mean, we performed analyses of covariance including baseline health status as a covariate. Given an equal (or averaged) score at baseline, the NYHA functional class II and III patients did not significantly differ with respect to their change in health status from baseline to 12 months after implantation ( Table 2 ). However, when adjusted for demographic and clinical factors, NYHA functional class II patients scored on average 10.15 points higher on general health (SE 3.31, p = 0.003) and 10.64 points higher on social functioning (SE 3.74, p = 0.005) at 12 months after implantation compared to the NYHA functional class III patients.


Dec 16, 2016 | Posted by in CARDIOLOGY | Comments Off on Effect of Cardiac Resynchronization Therapy-Defibrillator Implantation on Health Status in Patients With Mild Versus Moderate Symptoms of Heart Failure

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