The present study defined the short- and long-term effects of left ventricular assist device (LVAD) implantation and heart transplantation (HT) on physical activity and quality of life (QoL). Forty patients (LVAD, n = 14; HT, n = 12; and heart failure [HF], n = 14) and 14 matched healthy subjects were assessed for physical activity, energy expenditure, and QoL. The LVAD and HT groups were assessed postoperatively at 4 to 6 weeks (baseline) and 3, 6, and 12 months. At baseline, LVAD, HT, and HF patients demonstrated low physical activity, reaching only 15%, 28%, and 51% of that of healthy subjects (1,603 ± 302 vs 3,036 ± 439 vs 5,490 ± 1,058 vs 10,756 ± 568 steps/day, respectively, p <0.01). This was associated with reduced energy expenditure and increased sedentary time (p <0.01). Baseline QoL was not different among LVAD, HT, and HF groups (p = 0.44). LVAD implantation and HT significantly increased daily physical activity by 60% and 52%, respectively, from baseline to 3 months (p <0.05), but the level of activity remained unchanged at 3, 6, and 12 months. The QoL improved from baseline to 3 months in LVAD implantation and HT groups (p <0.01) but remained unchanged afterward. At any time point, HT demonstrated higher activity level than LVAD implantation (p <0.05), and this was associated with better QoL. In contrast, physical activity and QoL decreased at 12 months in patients with HF (p <0.05). In conclusion, patients in LVAD and HT patients demonstrate improved physical activity and QoL within the first 3 months after surgery, but physical activity and QoL remain unchanged afterward and well below that of healthy subjects. Strategies targeting low levels of physical activity should now be explored to improve recovery of these patients.
Physical inactivity increases the risk for all-cause and cardiovascular mortality by 30% to 40% in the general population and is considered as an independent risk factor for heart failure (HF). Conversely, habitual physical activity, that is, daily walking performance, as objectively evaluated by an accelerometer, is an important determinant of functional capacity in patients with chronic HF. Furthermore, increased physical activity in the form of a structured exercise intervention improves exercise tolerance and quality of life (QoL) in HF and heart transplantation (HT) patients, but limited number of studies evaluated its impact in patients implanted with a left ventricular assist device (LVAD). Before critically evaluating exercise as a potential therapy for patients on LVAD support, it is important to understand the pattern of habitual, daily physical activity and its relation to QoL. Consequently, the aim of this study was to define the short- and long-term effects of LVAD implantation and HT on everyday physical activity, energy expenditure, and QoL.
Methods
A prospective, observational, repeated-measures design was chosen to characterize changes over time that occur in physical activity and QoL in patients on LVAD support and HT patients. The setting for the study was an inpatient HT assessment. Based on the assessment, patients were listed for HT, if judged to be too unwell to wait for a transplant, or an LVAD was implanted, if they would become better transplant candidates after a period of LVAD support. Those too well for transplant were continued on optimal medical management. These 3 scenarios were the basis of the 3 patients groups: LVAD, HT, and HF. HF patients had not received LVAD or HT during the study. Changes in physical activity and QoL of 12 HT patients were compared with those of 14 LVAD and 14 HF patients. Physical activity–related subgroup comparisons were performed with age-, gender-, and body mass index–matched 14 HF patients and 14 healthy subjects. In LVAD and HT patients, data on physical activity and QoL were collected at 4 different time points: baseline assessment, that is, 4 to 6 weeks after surgery and after discharge from hospital and then follow-up assessments at 3, 6, and 12 months after surgery. The data on patients with HF were collected at baseline and at 12 months, and on the healthy subjects data were only collected at 1 time point. Both LVAD and HT patients completed in-hospital postsurgery mobility and rehabilitation program guided by a physiotherapist. The study protocol was approved by the County Durham and Tees Valley Research and Ethics Committee. All participants gave written informed consent. All clinical investigations were conducted according to the principles expressed in the Declaration of Helsinki.
All patients undergoing LVAD implantation (HeartWare, HeartWare International Inc., Framingham, Massachusetts) or HT who met study inclusion criteria were recruited into the study from September 2010 to June 2013 at the Freeman Hospital, Newcastle upon Tyne, United Kingdom. Their baseline physical activity and QoL data were compared with those of 14 patients with chronic HF who were assessed but not listed for HT and 14 healthy participants. Subjects’ demographic and clinical characteristics are presented in Table 1 . The study inclusion criteria included age from 18 to 60 years, sufficient English language skills to answer the questionnaires, completion of follow-up visits, and willingness to participate. Study exclusion criteria included physical condition limiting rehabilitation or mobility such as stroke; myopathy; neuropathy; renal, pulmonary, or hepatic dysfunction; or active uncontrolled infection. Written informed consent was received from all subjects enrolled in the study.
| Patients Characteristics | LVAD (n = 14) | HT (n = 12) | HF (n = 14) | Healthy Subjects (n = 14) | ANOVA p Value |
|---|---|---|---|---|---|
| Age (years) | 49 ± 14 | 48 ± 17 | 46 ± 10 | 48 ± 14 | 0.959 |
| Men (%) | 100 | 70 | 67 | 71 | — |
| Weight (kg) | 85 ± 16 | 77 ± 11 | 80 ± 15 | 84 ± 17 | 0.617 |
| Height (cm) | 177 ± 10 | 170 ± 8 | 169 ± 9 | 174 ± 13 | 0.081 |
| Body mass index (kg/m 2 ) | 27 ± 6 | 27 ± 6 | 29 ± 5 | 27 ± 4 | 0.725 |
| Etiology of heart failure | |||||
| Idiopathic dilated cardiomyopathy | 5 | 6 | 11 | N/A | — |
| Ischemic cardiomyopathy | 9 | 2 | 3 | N/A | — |
| Other | — | 4 | — | N/A | — |
| LVEF (%) | 13 ± 2 | 14 ± 6 | 18 ± 3 | 64 ± 8 | 0.004 ∗ |
| NYHA class | 3.7 ± 0.2 | 3.8 ± 0.3 | 3.3 ± 0.5 | — | |
| Cardiac index (l/min/m 2 ) | 1.7 ± 0.4 | 1.8 ± 0.3 4 | 2.1 ± 0.4 | 3.6 ± 0.7 | 0.002 ∗ |
| Peak O 2 consumption (ml/kg/min) | 9.9 ± 2.1 | 10.2 ± 2.3 | 14.6 ± 2.8 | 34.6 ± 9.2 | |
| INTERMACS score | 2.8 ± 0.9 | — | — | — | — |
∗ Healthy versus LVAD, HT, and chronic heart failure (p <0.01).
Patients on LVAD support were treated with warfarin for a target international normalized ratio of 2.7 and antiplatelets as well as with angiotensin-converting enzyme inhibitors, β blockers, aldosterone antagonists, angiotensin receptor blockers, and diuretics as appropriate. HT patients received triple-drug immunosuppressive maintenance therapy, usually including a calcineurin inhibitor, prednisolone, and azathioprine. Patients with chronic HF were treated with β blockers (n = 14), angiotensin-converting enzyme inhibitors (n = 10), aldosterone antagonists (n = 6), diuretics (n = 12), statins (n = 8), angiotensin receptor blockers (n = 5), anticoagulants (n = 9), antiarrhythmics (n = 5), and digoxin (n = 3).
Habitual physical activity was objectively evaluated using a validated portable multisensor array (SenseWear Pro3, BodyMedia Inc., Pennsylvania). The monitor was worn for 7 days and was only removed for bathing. The multisensor array measures 4 key metrics: skin temperature, galvanic skin response, heat flux, and motion by way of a 3-axis accelerometer. The sensors, combined with algorithms, calculate the average daily energy expenditure relative to baseline metabolism (metabolic equivalent: MET per day [1 MET = resting metabolic rate]), total energy expenditure (calories per day), active energy expenditure (total calories expended over 3 METs per day), physical activity duration (minutes >3 METs per day), average daily number of steps walked, sedentary activity (minutes <3 METs per day), moderate activity (minutes between 3 and 6 METs per day), vigorous activity (minutes between 6 and 9 METs day), and very vigorous activity (minutes >6 METs day). HF-related QoL was assessed with the Minnesota Living with Heart Failure (MLHF) Questionnaire.
All statistical analyses were carried out using SPSS, version 19.0 (SPSS Inc., Chicago, Illinois). Before statistical analysis, data were checked for univariate and multivariate outliers using standard z-distribution cutoffs and Mahalanobis distance tests. Normality of distribution was assessed using a Kolmogorov-Smirnov test. Analysis of variance was used to test differences in physical activity and QoL among LVAD, HT, and HF patients and healthy controls as well as to evaluate changes at different time points in LVAD and HT patients. To identify groups that differed significantly from one another, a post hoc Tukey test was performed. The relation between QoL and physical activity in the patients was evaluated using the Pearson coefficient of correlation. Statistical significance was indicated if p <0.05. All data are presented as mean ± SEM unless otherwise indicated.
Results
The total number of patients screened for the study was 52 (18 LVAD, 14 HT, and 20 HF). Study participants’ demographic and clinical characteristics are described in Table 1 . The groups were not randomly assigned, and the treatment was based on the outcome of the transplant assessment. No significant differences were found in age and body mass index among LVAD, HT, HF, and healthy subjects. During the follow-up study, 2 patients in the LVAD group died and 2 refused to complete the study. There were 8 hospitalizations in 7 patients in the LVAD group for infections, 2 hospitalizations for arrhythmias, 1 with HF, 1 anemia, 1 with a transient ischemic attack, 1 with a possible deep vein thrombosis, and 1 with light-headedness. Of the heart transplant patients, 3 patients had admissions for infections and 1 patient had 3 admissions for rejection. Of the 20 patients with HF who were initially screened, 4 refused to take part in the study, 2 received HT, and 10 of remaining 14 patients completed investigation at 12 months after the baseline assessment.
Baseline physical activity measures demonstrated that patients in the LVAD and HT groups expended 25% (716 kcal) and 22% (640 kcal) less energy per day, respectively, in comparison with healthy subjects (p <0.05). Similarly, patients with HF expended 27% (772 kcal) less energy per day than healthy subjects ( Table 2 ). Daily physical activity (i.e., number of steps) was significantly reduced in the 3 patient groups with LVAD and HT patients at baseline performing only 15% and 28% and HF 51% of that of healthy subjects ( Table 2 ). At baseline, duration of physical activity (i.e., >3 METs) was significantly reduced in LVAD patients compared with both HT and HF patients ( Table 2 ). LVAD and HT patients showed active energy expenditure that was significantly lower than that of healthy subjects ( Table 2 ). Moderate physical activity, that is, 3 to 6 METs, was a major contributor to active energy expenditure in all 4 groups. Vigorous physical activity was identified in healthy and HT participants but not in LVAD and HF patients ( Table 2 ). The MLHF QoL score was not significantly different among the 3 groups of patients at baseline ( Table 2 ).
| Variables | LVAD | HT | HF | Healthy Subjects | ANOVA p Value |
|---|---|---|---|---|---|
| Total energy expenditure (kcal/day) | 2164 ± 112 | 2240 ± 163 | 2108 ± 211 | 2880 ± 153 | 0.004 ∗ |
| Steps (per day) | 1603 ± 302 | 3036 ± 439 | 5490 ± 1058 | 10,756 ± 568 | <0.001 ∗ † |
| Average METs (kcal/kg/hour) | 1.07 ± 0.06 | 1.28 ± 0.08 | 1.23 ± 0.06 | 1.45 ± 0.04 | <0.001 ∗ ‡ |
| Active energy expenditure (kcal/day) | 78 ± 30 | 330 ± 129 | 313 ± 95 | 751 ± 77 | <0.001 ∗ ‡ |
| Physical activity duration (min/day) | 18 ± 8 | 69 ± 22 | 65 ± 18 | 128 ± 10 | <0.001 ∗ ‡ |
| Sedentary time (min/day) | 1410 ± 10 | 1303 ± 32 | 1322 ± 24 | 1261 ± 17 | <0.001 ‡ |
| Moderate physical activity (min/day) | 18 ± 8 | 66 ± 25 | 64 ± 18 | 120 ± 9 | <0.001 ∗ ‡ |
| Vigorous physical activity (min/day) | 0 ± 0 | 3.5 ± 2.3 | 0.5 ± 0.3 | 5.9 ± 1.7 | 0.014 § |
| Very vigorous physical activity (min/day) | 0 ± 0 | 0.1 ± 0.3 | 0 ± 0 | 1.6 ± 1.5 | 0.489 |
| MLHF quality of life | 81 ± 5 | 72 ± 8 | 74 ± 4 | N/A | 0.445 |
∗ Healthy versus LVAD, HT, and HF (p <0.05).
‡ LVAD versus HF, HT, and healthy (p <0.05).
During the follow-up period there were no significant changes in body mass during 12 months after LVAD implantation or HT. The body mass was also not changed in patients with HF. Total daily energy expenditure increased significantly from baseline to 3 months in LVAD patients (p <0.05) but remained unchanged from 3 to 12 months after the surgery. In contrast, HT patients demonstrated significantly higher total energy expenditure at 12 months ( Table 3 ). Daily number of steps significantly increased by 60% and 52% from baseline to 3 months in LVAD and HT patients, respectively. It remained, however, unchanged from 3 to 12 months and significantly lower than that of healthy subjects ( Figure 1 ). This was further associated with significant increase in physical activity duration and active energy expenditure ( Figure 1 ). MLHF scores decreased over time from baseline in both LVAD and HT patients indicating an improvement in QoL ( Table 3 , Figure 1 ). In contrast with LVAD and HT patients, those with HF had decreased daily number of steps, activity duration, and active energy expenditure at 12 months from baseline and increased MLHF scores ( Figure 1 ).
| Variables | Patient Group | Baseline | 3 Months | 6 Months | 12 Months |
|---|---|---|---|---|---|
| Weight (kg) | LVAD | 86 ± 17 | 86 ± 16 | 89 ± 16 | 83 ± 11 |
| HT | 76 ± 15 | 78 ± 14 | 77 ± 15 | 80 ± 17 | |
| HF | 81 ± 17 | — | — | 82 ± 16 | |
| Steps (per day) | LVAD | 1603 ± 302 | 3712 ± 807 | 4007 ± 1084 | 3997 ± 956 ∗ |
| HT | 3036 ± 439 | 6265 ± 443 | 6563 ± 824 | 6288 ± 701 ∗ | |
| HF | 5490 ± 1058 | — | — | 3560 ± 885 ∗ † | |
| Total energy expenditure (kcal/day) | LVAD | 2164 ± 112 | 2392 ± 105 | 2398 ± 108 | 2421 ± 117 ∗ |
| HT | 2240 ± 163 | 2406 ± 137 | 2443 ± 148 | 3572 ± 202 ∗ ‡ | |
| HF | 2108 ± 211 | — | — | 1989 ± 198 † | |
| Average METs (kcal/kg/hour) | LVAD | 1.07 ± 0.06 | 1.18 ± 0.07 | 1.19 ± 0.08 | 1.20 ± 0.09 |
| HT | 1.28 ± 0.08 ‡ | 1.31 ± 0.05 | 1.35 ± 0.07 ‡ | 1.39 ± 0.06 ‡ | |
| HF | 1.23 ± 0.06 | — | — | 1.14 ± 0.05 † | |
| Sedentary time (min/day) | LVAD | 1410 ± 10 | 1353 ± 26 | 1293 ± 52 | 1280 ± 62 |
| HT | 1303 ± 32 | 1308 ± 21 | 1329 ± 18 | 1260 ± 29 | |
| HF | 1322 ± 24 | — | — | 1388 ± 21 † | |
| Moderate physical activity (min/day) | LVAD | 18 ± 8 | 48 ± 17 | 55 ± 16 | 51 ± 20 ∗ |
| HT | 66 ± 22 ‡ | 86 ± 46 ‡ | 84 ± 14 ‡ | 144 ± 22 § ‡ | |
| HF | 64 ± 18 | — | — | 41 ± 12 ∗ † | |
| Vigorous physical activity (min/day) | LVAD | 0 ± 0 | 1.3 ± 0.7 | 2.4 ± 1.9 | 0.5 ± 0.3 |
| HT | 3.5 ± 2.3 | 2.3 ± 1.3 | 2.9 ± 1.5 | 4.3 ± 2.3 | |
| HF | 0.5 ± 0.3 | — | — | 0 ± 0 | |
| Very vigorous physical activity (min/day) | LVAD | 0 ± 0 | 0 ± 0 | 0 ± 0 | 0 ± 0 |
| HT | 0 ± 0 | 0 ± 0 | 0 ± 0 | 0 ± 0 | |
| HF | 0 ± 0 | — | — | 0 ± 0 | |
| MLHF quality of life | LVAD | 81 ± 5 | 57 ± 7 | 63 ± 7 | 60 ± 5 ∗ |
| HT | 72 ± 8 | 39 ± 5 ‡ | 30 ± 6 ‡ | 29 ± 7 ∗ ‡ | |
| HF | 74 ± 4 | — | — | 82 ± 6 ∗ † ‖ |
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