Prithwish Banerjee

Diastolic heart failure: neglected or misdiagnosed?

Recent epidemiological studies suggest that 30% to 50% of patients with heart failure (HF) have preserved left ventricular (LV) systolic function. These patients, often presumed to have diastolic heart failure (DHF), appear to have lower short-term but similar long-term mortality when compared to patients with HF and LV systolic dysfunction. Rates of recurrent hospitalization and costs of care appear similar in the two groups of patients. Therefore, DHF may contribute significantly to the burden of disease caused by HF. Exertional breathlessness, the principal symptom of HF, has many causes, including obesity, pulmonary disease and myocardial ischemia. A diagnosis of DHF by exclusion, based on symptoms in the absence of important LV systolic dysfunction or major valve disease, is unsatisfactory. Unfortunately, as yet, no reliable definition with which to make a positive diagnosis of DHF has been agreed on, frequently rendering this diagnosis uncertain. Echocardiography has several limitations, whereas hemodynamic confirmation of DHF by cardiac catheterization is potentially complex and not practically feasible for many patients. Treatment of DHF remains empirical and unsatisfactory because of the lack of large-scale randomized controlled trials in this area. Currently, three large outcome studies on DHF are in progress along with other smaller trials. These should start to provide some of the answers we need to diagnose and effectively treat DHF.

Prolonged Electrical Muscle Stimulation Exercise Improves Strength, Peak VO2, and Exercise Capacity in Patients With Stable Chronic Heart Failure

BACKGROUND Exercise training can help patients with chronic heart failure but may be limited in its applicability due to age and other comorbidities. This investigation evaluated training responses to prolonged electrical muscle stimulation (EMS) in patients with stable chronic heart failure. METHODS AND RESULTS In a crossover designed study, 10 patients (age 66 +/- 6.5 years, 9 male) were randomized to 8 weeks of training or habitual activity before crossing over to the other limb after a washout period of 2 weeks. Training consisted of electrical muscle stimulation of the major leg muscles for a minimum of 1 hour, 5 days a week. Peak oxygen consumption, 6-minute walking distance test, body mass index, and quadriceps muscle strength were the end points. At baseline the mean values for peak oxygen consumption (VO(2)), 6-minute walking distance, quadriceps strength, and body mass index were 19.5 +/- 3.5 mL x kg x min, 415.1 +/- 56.6m, 377.9 +/- 110.4N, and 27.9 +/- 3.1 kg/m(2), respectively. After training, peak VO(2) increased to 21.2 +/- 5.1 mL x kg x min (P < .05), walking distance increased to 454.9 +/- 54.5M (P < .005), quadriceps strength increased to 404.9 +/- 108.6N (P < .005), whereas we did not observe a significant effect on body mass index (P > .05). CONCLUSIONS EMS can be used in sedentary adults with stable chronic heart failure to improve physical fitness and functional capacity. It may provide a viable alternative for patients unable to undertake more conventional forms of exercise.

Diastolic heart failure. Paroxysmal or chronic

Heart failure with preserved systolic function is considered by some to be synonymous with diastolic heart failure (DHF). Although recent epidemiological studies have suggested that DHF constitutes 30–50% of all patients with heart failure, many cardiologists dealing with ambulant heart failure patients on a daily basis find that the vast majority of heart failure patients have systolic dysfunction. What could be the reasons for this? Referral bias and varying diagnostic thresholds and interpretation of results could be one important reason. Heart failure with preserved systolic function comprises a heterogeneous group of conditions: whilst some patients may truly have DHF, others may have heart failure due to subtle systolic dysfunction (noted on tissue Doppler imaging of the left ventricular long axis). Other patients actually have pulmonary disease, obesity or ischaemic heart disease, and have their symptoms attributed to ‘diastolic heart failure’ on the basis of ‘abnormal’ mitral diastolic flow indices that may, in fact, simply reflect aging. True DHF may be much less prevalent than suggested. A further possibility is that heart failure in patients with diastolic dysfunction might be paroxysmal rather than chronic. This group of patients may present predominantly to acute units like accident and emergency, coronary care units and intensive care units and are, therefore unlikely to figure prominently in the usual outpatient population of chronic systolic left ventricular dysfunction.

Electrical stimulation of unloaded muscles causes cardiovascular exercise by increasing oxygen demand

Background The development of new strategies to encourage increased levels of physical activity can help to reduce the incidence of cardiovascular disease. A new system of electrical muscle stimulation (EMS) has been developed that attempts to cause an increase in energy expenditure by mimicking the action of shivering in the body. The purpose of this study was to show that this form of EMS is capable of eliciting a cardiovascular exercise response in healthy adults. Design An observational study. Methods Ten healthy volunteers completed a maximal treadmill test and four EMS sessions using a hand-held EMS device that delivered current to the body via five silicone rubber electrodes on each leg. At each session subjects completed 3 min stimulation at each of four stimulation outputs (10, 20, 30 and 40% of maximum output) while cardiopulmonary gas exchange and heart rate (HR) were measured. Physiological responses at increasing levels of stimulation were evaluated. Results Average (±SD) HR and oxygen consumption (VO2) levels of 67 ± 11 bpm and 4.7 ± 1.2 ml/kg per min at rest, respectively, were increased to 186 ± 10 bpm and 44.9 ± 9.8 ml/kg per min at peak exercise intensity on treadmill testing. The electrical stimulation was generally well tolerated by the subjects. Subjects demonstrated statistically significant increases in all physiological variables measured with successive increases in stimulation intensity. Peak HR and VO2 at 40% stimulation intensity were 101 ±12 bpm and 14.9 ± 4.3 ml/kg per min, respectively. Conclusions These results demonstrate that this form of EMS is capable of producing a physiological response consistent with cardiovascular exercise at mild to moderate intensities. It achieves this without producing gross movement of the limbs or loading of the joints. This EMS-induced cardiovascular exercise response could be used to promote increased levels of physical activity in populations unable to participate in voluntary exercise.

Functional Cardiovascular Reserve Predicts Survival Pre-Kidney and Post-Kidney Transplantation

Exercise intolerance is an important comorbidity in patients with CKD. Anaerobic threshold (AT) determines the upper limits of aerobic exercise and is a measure of cardiovascular reserve. This study investigated the prognostic capacity of AT on survival in patients with advanced CKD and the effect of kidney transplantation on survival in those with reduced cardiovascular reserve. Using cardiopulmonary exercise testing, cardiovascular reserve was evaluated in 240 patients who were waitlisted for kidney transplantation between 2008 and 2010, and patients were followed for ≤5 years. Survival time was the primary endpoint. Cumulative survival for the entire cohort was 72.6% (24 deaths), with cardiovascular events being the most common cause of death (54.2%). According to Kaplan-Meier estimates, patients with AT <40% of predicted peak VO2 had a significantly reduced 5-year cumulative overall survival rate compared with those with AT ≥40% (P<0.001). Regarding the cohort with AT <40%, patients who underwent kidney transplantation (6 deaths) had significantly better survival compared with nontransplanted patients (17 deaths) (hazard ratio, 4.48; 95% confidence interval, 1.78 to 11.38; P=0.002). Survival did not differ significantly among patients with AT ≥40%, with one death in the nontransplanted group and no deaths in the transplanted group. In summary, this is the first prospective study to demonstrate a significant association of AT, as the objective index of cardiovascular reserve, with survival in patients with advanced CKD. High-risk patients with reduced cardiovascular reserve had a better survival rate after receiving a kidney transplant.

Electrical Muscle Stimulation for Chronic Heart Failure: An Alternative Tool for Exercise Training?

Conventional exercise training has been shown conclusively to improve exercise capacity, quality of life, and even reduce mortality in chronic heart failure. Unfortunately, not all heart failure patients are suitable for conventional exercise programs for various reasons. The exciting new technique of electrical muscle stimulation (EMS) of large groups of muscles has been shown to produce a physiologic response consistent with cardiovascular exercise at mild to moderate intensities by increasing peak oxygen consumption, carbon dioxide production, ventilatory capacity, and heart rate. Additionally, there is improvement in muscle strength. The handful of small studies that exist of home-based EMS training of leg muscles in heart failure show that EMS produces similar benefits to conventional exercise in improving exercise capacity, making EMS an alternative to aerobic exercise training in those that cannot undertake conventional exercise. The improvement seen in leg muscle strength promises also to improve mobility in this sedentary population.

Reduced functional measure of cardiovascular reserve predicts admission to critical care unit following kidney transplantation

Background There is currently no effective preoperative assessment for patients undergoing kidney transplantation that is able to identify those at high perioperative risk requiring admission to critical care unit (CCU). We sought to determine if functional measures of cardiovascular reserve, in particular the anaerobic threshold (VO2AT) could identify these patients. Methods Adult patients were assessed within 4 weeks prior to kidney transplantation in a University hospital with a 37-bed CCU, between April 2010 and June 2012. Cardiopulmonary exercise testing (CPET), echocardiography and arterial applanation tonometry were performed. Results There were 70 participants (age 41.7±14.5 years, 60% male, 91.4% living donor kidney recipients, 23.4% were desensitized). 14 patients (20%) required escalation of care from the ward to CCU following transplantation. Reduced anaerobic threshold (VO2AT) was the most significant predictor, independently (OR = 0.43; 95% CI 0.27–0.68; p<0.001) and in the multivariate logistic regression analysis (adjusted OR = 0.26; 95% CI 0.12–0.59; p = 0.001). The area under the receiver-operating-characteristic curve was 0.93, based on a risk prediction model that incorporated VO2AT, body mass index and desensitization status. Neither echocardiographic nor measures of aortic compliance were significantly associated with CCU admission. Conclusions To our knowledge, this is the first prospective observational study to demonstrate the usefulness of CPET as a preoperative risk stratification tool for patients undergoing kidney transplantation. The study suggests that VO2AT has the potential to predict perioperative morbidity in kidney transplant recipients.

High-intensity interval training versus moderate-intensity steady-state training in UK cardiac rehabilitation programmes (HIIT or MISS UK): study protocol for a multicentre randomised controlled trial and economic evaluation

Introduction Current international guidelines for cardiac rehabilitation (CR) advocate moderate-intensity exercise training (MISS, moderate-intensity steady state). This recommendation predates significant advances in medical therapy for coronary heart disease (CHD) and may not be the most appropriate strategy for the ‘modern’ patient with CHD. High-intensity interval training (HIIT) appears to be a safe and effective alternative, resulting in greater improvements in peak oxygen uptake (VO2 peak). To date, HIIT trials have predominantly been proof-of-concept studies in the laboratory setting and conducted outside the UK. The purpose of this multicentre randomised controlled trial is to compare the effects of HIIT and MISS training in patients with CHD attending UK CR programmes. Methods and analysis This pragmatic study will randomly allocate 510 patients with CHD to 8 weeks of twice weekly HIIT or MISS training at 3 centres in the UK. HIIT will consist of 10 high-intensity (85–90% peak power output (PPO)) and 10 low-intensity (20–25% PPO) intervals, each lasting 1 min. MISS training will follow usual care recommendations, adhering to currently accepted UK guidelines (ie, >20 min continuous exercise at 40–70% heart rate reserve). Outcome measures will be assessed at baseline, 8 weeks and 12 months. The primary outcome for the trial will be change in VO2 peak as determined by maximal cardiopulmonary exercise testing. Secondary measures will assess physiological, psychosocial and economic outcomes. Ethics and dissemination The study protocol V.1.0, dated 1 February 2016, was approved by the NHS Health Research Authority, East Midlands—Leicester South Research Ethics Committee (16/EM/0079). Recruitment will start in August 2016 and will be completed in June 2018. Results will be published in peer-reviewed journals, presented at national and international scientific meetings and are expected to inform future national guidelines for exercise training in UK CR. Trial registration number NCT02784873; pre-results.

Randomised feasibility trial into the effects of low-frequency electrical muscle stimulation in advanced heart failure patients

Objectives Low-frequency electrical muscle stimulation (LF-EMS) may have the potential to reduce breathlessness and increase exercise capacity in the chronic heart failure population who struggle to adhere to conventional exercise. The study’s aim was to establish if a randomised controlled trial of LF-EMS was feasible. Design and setting Double blind (participants, outcome assessors), randomised study in a secondary care outpatient cardiac rehabilitation programme. Participants Patients with severe heart failure (New York Heart Association class III–IV) having left ventricular ejection fraction <40% documented by echocardiography were eligible. Interventions Participants were randomised (remotely by computer) to 8 weeks (5×60 mins per week) of either LF-EMS intervention (4 Hz, continuous, n=30) or sham placebo (skin level stimulation only, n=30) of the quadriceps and hamstrings muscles. Participants used the LF-EMS straps at home and were supervised weekly Outcome measures Recruitment, adherence and tolerability to the intervention were measured during the trial as well as physiological outcomes (primary outcome: 6 min walk, secondary outcomes: quadriceps strength, quality of life and physical activity). Results Sixty of 171 eligible participants (35.08%) were recruited to the trial. 12 (20%) of the 60 patients (4 LF-EMS and 8 sham) withdrew. Forty-one patients (68.3%), adhered to the protocol for at least 70% of the sessions. The physiological measures indicated no significant differences between groups in 6 min walk distance(p=0.13) and quality of life (p=0.55) although both outcomes improved more with LF-EMS. Conclusion Patients with severe heart failure can be recruited to and tolerate LF-EMS studies. A larger randomised controlled trial (RCT) in the advanced heart failure population is technically feasible, although adherence to follow-up would be challenging. The preliminary improvements in exercise capacity and quality of life were minimal and this should be considered if planning a larger trial. Trial registration number ISRCTN16749049

Urinary retention and heart failure: One of the many precipitating causes of decompensation

Decompensation of stable chronic heart failure is common and debilitating. Urinary retention has not previously been described as a precipitating cause of decompensated heart failure. We present a series of case reports arguing that urinary retention is a common but unrecognised cause of decompensated heart failure. One of the biggest current problems with the large population of chronic heart failure patients worldwide is frequent decompensation leading to repeated hospital admissions [1]. This leads to a massive pressure on existing medical resources as well as imposing a huge financial burden [2]. We present a series of case reports highlighting the role of urinary retention in the heart failure (HF) population and the importance of recognising this as a precipitating factor causing decompensation. A 68-year-oldmanwith severe left ventricular systolic dysfunction (LVSD) and Chronic Obstructive Pulmonary Disease was admitted with increasing shortness of breath (NYHA class IV) and gross peripheral lower limb oedema. For several weeks he had noticed increasing urinary frequency and hesitancy which culminated in first the worsening breathlessness and then limb oedema. Clinically he was found to be in decomsensated heart failure and urinary retention. He was already on maximal medical therapy for heart failure. Urinary catheterisation was promptly performed which together with diuretics helped to alleviate his symptoms of breathlessness (NYHA class II) and corrected his fluid balance. Review by the urologist confirmed that his urinary symptoms were due to Benign