Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome of exercise intolerance due to impaired myocardial relaxation and/or increased stiffness. Patients with HFpEF often show signs of chronic systemic inflammation, and experimental studies have shown that interleukin-1 (IL-1), a key proinflammatory cytokine, impairs myocardial relaxation. The aim of the present study was to determine the effects of IL-1 blockade with anakinra on aerobic exercise capacity in patients with HFpEF and plasma C-reactive protein (CRP) >2 mg/L (reflecting increased IL-1 activity). A total of 12 patients were enrolled in a double-blind, randomized, placebo-controlled, crossover trial and assigned 1:1 to receive 1 of the 2 treatments (anakinra 100 mg or placebo) for 14 days and an additional 14 days of the alternate treatment (placebo or anakinra). The cardiopulmonary exercise test was performed at baseline, after the first 14 days, and after the second 14 days of treatment. The placebo-corrected interval change in peak oxygen consumption was chosen as the primary end point. All 12 patients enrolled in the present study and receiving treatment completed both phases and experienced no major adverse events. Anakinra led to a statistically significant improvement in peak oxygen consumption (+1.2 ml/kg/min, p = 0.009) and a significant reduction in plasma CRP levels (−74%, p = 0.006). The reduction in CRP levels correlated with the improvement in peak oxygen consumption (R = −0.60, p = 0.002). Three patients (25%) had mild and self-limiting injection site reactions. In conclusion, IL-1 blockade with anakinra for 14 days significantly reduced the systemic inflammatory response and improved the aerobic exercise capacity of patients with HFpEF and elevated plasma CRP levels.
Heart failure (HF) is a clinical syndrome of exercise intolerance secondary to impaired cardiac function. Approximately 50% of patients with HF have preserved left ventricular systolic function (HF with preserved ejection fraction [HFpEF]) characterized by impaired left ventricular diastolic filling due to incompletely characterized mechanisms. Observational studies have linked markers of systemic inflammation with impaired cardiac function and a poor prognosis in patients with HFpEF and in patients with chronic inflammatory disease. Interleukin-1 (IL-1) is an apical cytokine involved in local and systemic inflammatory processes. IL-1 induces changes in systolic and diastolic function in experimental animal studies. Patients with rheumatoid arthritis (an IL-1–related disease) show signs of impaired left ventricular diastolic function, and treatment with anakinra—an IL-1 blocker—restored normal left ventricular diastolic function within hours of treatment. Anakinra has been approved for the treatment of chronic systemic inflammatory diseases and has recently been shown to reduce the incidence of HF after ST-segment elevation acute myocardial infarction and to improve aerobic exercise capacity in patients with HF and reduced ejection fraction. We present the effects of anakinra on aerobic exercise capacity and ventilatory efficiency in a randomized, double-blind, placebo-controlled, crossover pilot trial in patients with HFpEF and systemic inflammation (plasma C-reactive protein [CRP] levels >2 mg/L).
Methods
The study design of the Diastolic Heart failure Anakinra Response Trial (D-HART) was registered in www.clinicaltrials.gov (registration no. NCT01542502 ). The Food and Drug Administration granted an exemption for investigational new drug use. The study was approved by the local institutional review board, and all patients provided written informed consent. The inclusion criteria were age >18 years, New York Heart Association class II-III HF symptoms (without changes in class or treatment in the previous 3 months), preserved left ventricular ejection fraction (>50%) with left ventricular end-diastolic volume index (<97 ml/m 2 ), and evidence of abnormalities in left ventricular relaxation, filling, distensibility, or stiffness, as defined by the European Heart Society consensus document. Patients were excluded for any of the following conditions: HF hospitalization within the previous 12 months; recent (<3 months) changes in medical therapy for HF; concomitant conditions or treatments affecting completion or interpretation of the cardiopulmonary exercise test (i.e., physical inability to walk on a treadmill, significant myocardial ischemia, angina, uncontrolled arterial hypertension [at rest or during the baseline exercise test], atrial fibrillation, moderate to severe aortic or mitral valve disease, chronic pulmonary disease limiting exertion, or anemia [defined as hemoglobin <10 g/dl]; recent use of systemic immunosuppressive or anti-inflammatory drugs (not including nonsteroidal anti-inflammatory drugs); chronic inflammatory or infectious diseases; stage IV-V kidney disease; neutropenia (<2,000/mm 3 ); pregnancy; and any malignancy or any condition limiting survival or the ability to complete the study. After the initial screening, the patients were assessed for systemic inflammation, defined as plasma high-sensitivity CRP levels >2 mg/L, using an automated high-sensitivity latex-enhanced assay.
All patients underwent cardiopulmonary exercise testing at baseline and at completion of 14 and 28 days of treatment. The cardiopulmonary exercise test was administered using a metabolic cart interfaced with a treadmill (Vmax Encore, Viasys, Yorba Linda, California). A conservative ramping treadmill protocol was used, as described previously. Expired gases were sampled using a mouthpiece-mounted sensor and analyzed to continuously measure the oxygen consumption (VO 2 ), carbon dioxide production (VCO 2 ), and minute ventilation (VE). The peak VO 2 , VE/VCO 2 slope, and oxygen uptake efficiency slope (OUES) were determined as described, with the first measuring aerobic exercise capacity and the others ventilatory efficiency, the ability to expel carbon dioxide and consume oxygen at an appropriately low minute ventilation. All patients also completed an HF symptom questionnaire (Duke Activity Status Index). The investigational pharmacist performed randomization using a dedicated randomization algorithm prepared online (at randomization.com ) by 1 of the investigators not involved in the conduct of the study (seed no. 26404, created on November 29, 2011). For each patient, the pharmacist prepared 2 indistinguishable sets of 14 syringes containing 100 mg of anakinra (Kineret, Swedish Orphan Biovitrum, Stockholm, Sweden) in 0.67 ml and matching NaCl 0.9% placebo. Treatment consisted of 2 courses of 14 daily subcutaneous injections without any washout period. Each patient was randomized to receive either active treatment first followed by placebo or vice versa. All cardiopulmonary exercise tests were performed by a single operator. The data were electronically transferred, and all calculations related to the cardiopulmonary exercise test were performed in Dr. Arena’s core laboratory. The primary end point was the placebo-corrected difference in the interval change in peak VO 2 from baseline to the post-treatment follow-up point. The secondary end points included the placebo-corrected differences in the interval changes in the CRP plasma levels and ventilatory efficiency (VE/VCO 2 ratio for carbon dioxide slope and OUES). Sample size calculations relied on a pilot study of anakinra in patients with HF and reduced ejection fraction, in which an identical 14-day treatment with anakinra had produced a median improvement in peak VO 2 of +2.8 ml/kg/min (SD 1.2). We, therefore, calculated that a crossover trial would require a sample size of 14 patients to provide a power of >80% (alpha = 0.05) to detect a difference of 1.4 ml/kg/min (SD 1.2) and <20% loss to follow-up. The data are reported as the median and interquartile range to account for potential deviations from the gaussian distribution. The differences in the interval changes between groups were analyzed using a random-effect general linear model for repeated measures to analyze the effects of time and group allocation, comparing on-treatment time 1 and on-treatment time 2, using baseline time 0 as a covariate. The differences are presented as changes in the median values for all variables. The Spearman correlation test was used to evaluate the correlations among the variables. Statistical significance was set at p = 0.05 level, and unadjusted p values are reported. Computations were performed using SPSS, version 21 (IBM, Armonk, New York).
Results
From January 2012 to May 2013, we screened 23 patients with stable HFpEF (diagnosed according to the European Society of Cardiology criteria) and enrolled 14 patients with CRP >2.0 mg/L, excluding 9 patients with CRP ≤2 mg/L ( Figure 1 ). Of the 14 patients, 1 provided written informed consent but did not complete any of the study tests nor receive treatment, and 1 completed the baseline cardiopulmonary exercise test but experienced angina and, therefore, was excluded from the study before administration of any study treatment. Thus, 12 patients received the study medication and were included in the final analysis. Of these, 11 patients (92%) were women, 4 (33%) were self-defined white and 8 (67%) self-defined black. The median age was 62 years. All 12 patients had systemic arterial hypertension, and 3 patients (25%) had echocardiographic evidence of left ventricular hypertrophy. All patients were obese (defined as body mass index of ≥30 kg/m 2 ; median body mass index 39 kg/m 2 ; range 30 to 50), with 4 (33%) having a body mass index >40 kg/m 2 . The median left ventricular ejection fraction was 58%, and the median E/E′ was 11. Of the 12 patients, 6 (50%) had New York Heart Association class II symptoms and 6 (50%) class III symptoms, with a median symptom duration of 20 months (range 6 to 36). None of the patients had moderate or severe impairment in the glomerular filtration rate (<60 ml/kg/1.73 m 2 ). All patients were being treated with furosemide, 10 patients (83%) were being treated with either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker, and 10 (83%) were being treated with β-adrenergic blockers, with all 12 patients (100%) receiving either class of drugs and 8 (67%) receiving both. Finally, 2 patients (17%) were receiving spironolactone and 11 patients (92%) were being treated with a statin plus aspirin. The clinical characteristics of the 12 patients are listed in Table 1 .
| Pt. No. | Age (yrs) | Gender | Ethnicity | HTN | DM | NYHA Class | BNP (pg/ml) | hs-CRP (mg/L) | LVEF (%) | LVEDVi (ml/m 2 ) | LVMi (g/m 2 ) | E/E′ | LVEDP | Peak VO 2 | VE/VCO 2 | OUES | Change in Peak VO 2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 40 | F | White | Yes | No | 2 | 43 | 4.7 | 63 | 33 | 72 | 24 | NA | 16.9 | 24.6 | 2.08 | +1.9 |
| 2 | 52 | F | Black | Yes | No | 2 | 8 | 9.9 | 63 | 43 | 131 | 8 | NA | 20.5 | 23.2 | 2.21 | −1.1 |
| 3 | 55 | F | Black | Yes | Yes | 3 | 39 | 3.5 | 57 | 59 | 123 | 11 | 18 | 16.2 | 30.6 | 1.79 | +1.7 |
| 4 | 55 | F | Black | Yes | No | 2 | 19 | 6.6 | 58 | 33 | 91 | 11 | NA | 18.7 | 22.3 | 2.85 | −1.0 |
| 5 | 57 | F | Black | Yes | Yes | 2 | 2 | 17.0 | 57 | 41 | 79 | 11 | 17 | 14.1 | 25.2 | 2.12 | +3.0 |
| 6 | 60 | F | Black | Yes | Yes | 3 | 25 | 11.5 | 60 | 62 | 125 | 15 | NA | 13.8 | 24.9 | 1.92 | −0.7 |
| 7 | 62 | F | White | Yes | Yes | 3 | 39 | 5.0 | 64 | 37 | 68 | 11 | 34 | 16.1 | 29.6 | 2.54 | +2.1 |
| 8 | 63 | F | Black | Yes | No | 2 | 11 | 15.2 | 74 | 34 | 89 | 21 | 20 | 14.4 | 22.2 | 1.8 | +0.4 |
| 9 | 64 | F | White | Yes | Yes | 3 | 112 | 2.6 | 53 | 40 | 78 | 10 | NA | 13.1 | 33 | 1.34 | +1.7 |
| 10 | 64 | F | Black | Yes | Yes | 3 | 131 | 15.5 | 67 | 41 | 90 | 20 | NA | 11.4 | 21.1 | 2.02 | +3.5 |
| 11 | 65 | M | White | Yes | Yes | 2 | 23 | 3.1 | 59 | 60 | 68 | 11 | NA | 17.3 | 31.1 | 1.73 | +3.0 |
| 12 | 70 | F | Black | Yes | No | 3 | 414 | 18.2 | 51 | 78 | 100 | 19 | 15 | 9.4 | 45.4 | 1.22 | +1.8 |
Of the 12 patients, 6 received anakinra first and 6 placebo, with the first dose given immediately after the baseline cardiopulmonary exercise test. The patients were then given a supply of 13 additional syringes to self-administer at home each day. All 12 patients completed the second cardiopulmonary exercise test 14 days later, received the second batch of (crossover) syringes, and completed the third cardiopulmonary exercise test another 14 days later ( Figure 1 ). With the exception of the patient who experienced angina during the baseline cardiopulmonary exercise test (before any treatment), none of the treated patients experienced any serious adverse events or requested treatment discontinuation. Three patients (25%) experienced mild injection site reactions with anakinra, but no injection site reactions were reported with placebo.
The on-treatment peak VO 2 was 16.3 ml/kg/min (range 13.8 to 17.5) with anakinra compared with 15.1 ml/kg/min (range 11.3 to 17.3) with placebo, leading to a placebo-corrected difference in the median peak VO 2 (primary end point) of 1.2 ml/kg/min (+8%, p = 0.009; Figure 2 ). The placebo-corrected changes in peak VO 2 for each patient are listed in Table 1 . Anakinra treatment also led to a significant reduction in the plasma CRP levels (placebo-corrected difference of −6.1 mg/L [−74%], p = 0.006; Figure 2 ). No significant effect was seen on the VE/VCO 2 ratio for carbon dioxide slope, a measure of ventilatory efficiency ( Figure 2 ); however, a sensitivity analysis showed significant improvement in the VE/VCO 2 ratio for carbon dioxide slope in the subgroup of patients who had had greater median VE/VCO 2 ratio for carbon dioxide slope values (>25, n = 5) at baseline (placebo-corrected difference 3.8 [12%], favoring anakinra; p = 0.047). Treatment with anakinra improved the OUES, another measure of ventilatory efficiency (placebo-corrected difference 0.14 [7%], p = 0.006; Figure 2 ). The interval changes in the CRP levels correlated inversely with the changes in peak VO 2 (R = −0.60, p = 0.002), with a greater reduction in CRP associated with a greater increase in peak VO 2 ( Figure 3 ). Similarly, the leukocyte count in the peripheral blood was significantly reduced with anakinra (placebo-corrected difference −1,300/mm 3 , p = 0.005, with a 23% reduction in neutrophil count [p = 0.007] and a 20% reduction in monocyte count [p = 0.039]). Despite the small changes in the leukocyte count, it correlated significantly with the changes in peak VO 2 , with a greater reduction (with anakinra) predicting greater increases in peak VO 2 ( Figure 4 ). In contrast, no differences in the changes in brain-type natriuretic peptide levels were observed nor did the changes correlate with the changes in peak VO 2 ( Supplemental Figure 1 ). A trend was seen toward greater Duke Activity Status Index scores (reflecting improved perceived functional capacity) favoring anakinra (median +5.4 [0/+12.6], p = 0.068). Anakinra had no detectable effects on body weight, at rest or maximal heart rate or at rest or maximal systolic or diastolic blood pressure (data not shown). Although limited by the small numbers, none of the baseline clinical characteristics (e.g., gender, age, ethnicity, New York Heart Association class, brain-type natriuretic peptide level, left ventricular ejection fraction, E/E′ ratio, left ventricular mass or left atrial volume, diabetes, or medications) explored in the sensitivity analyses (using the variable as a covariate) influenced the effects of treatment on the peak VO 2 (p >0.10 for interaction for all).
