Daily Step Count as a Simple Marker of Disease Severity in Hypertrophic Cardiomyopathy

doi:10.1016/j.hlc.2017.12.012

Heart, Lung and Circulation

Volume 27, Issue 6, June 2018, Pages 752-755

https://doi.org/10.1016/j.hlc.2017.12.012 Get rights and content

Background

Individuals with hypertrophic cardiomyopathy (HCM) may be asymptomatic or display activity-limiting symptoms. A common cause of symptoms is left ventricular outflow tract obstruction (LVOTO), which may impact the individuals’ ability to undertake physical activity. This study sought to examine daily step count as a potential marker of exercise capacity, which may represent a proxy marker of disease severity in HCM.

Methods

A cross-sectional study of 63 HCM patients was conducted from March to November 2015. Participants wore an ActiGraph GT3X+ (Pensacola, Florida, USA) accelerometer for 7 days. Minutes per day of light, moderate and vigorous physical activity and step count were calculated, and those with LVOTO were compared to those without. Similarly, those with good functional capacity (New York Heart Association; NYHA class I) were compared to those with NYHA class II–IV.

Results

The majority of HCM patients were male (n = 45, 71%) with mean age of 48.8 ± 14.9 years. Hypertrophic cardiomyopathy patients with history of LVOTO and those NYHA class II–IV took significantly fewer steps per day (LV obstruction: 5527 ± 2370 versus 7027 ± 2095, p = 0.01 and NYHA: 5346 ± 1898 versus 6801 ± 2339, p = 0.03). No differences were observed across the different intensities of physical activity.

Conclusions

Measurement of daily step count may be a useful and simple tool to determine exercise capacity and provide an indicator of disease severity in individuals with HCM.

Introduction

Hypertrophic cardiomyopathy (HCM) is an inherited heart disease with prevalence of up to 1:200 people [1]. Individuals with HCM may be asymptomatic and diagnosed incidentally or as a result of family screening. Alternatively, patients may present with symptoms leading to cardiac investigations and diagnosis of HCM [2]. Symptoms related to HCM include dyspnoea and chest pain, and can be induced by left ventricular outflow tract obstruction (LVOTO) [3]. LVOTO is defined as a resting systolic pressure gradient in the outflow tract of greater than 30 mmHg, or an inducible gradient of greater than 50 mmHg [3], [4]. Presence of symptoms may impact on the individuals’ ability to undertake physical activity, leading to physical inactivity and potentially, development of non-communicable diseases such as diabetes and ischaemic heart disease [5].

The New York Heart Association (NYHA) classification is used to categorise patients based on severity of symptoms [6]. In general, those with LVOTO more often have severe symptoms resulting in a higher NYHA class, however, this is not always the case [4]. Simple methods that quantify physical activity levels may be helpful at the clinical level in the context of HCM and patient management decisions. Daily step count is a simple measure that can be obtained easily through use of a pedometer or activity tracker device. This study sought to examine daily step count as a potential marker of disease severity and exercise capacity in the setting of HCM.

Section snippets

Methods

A cross-sectional study of consecutive HCM patients attending the HCM and Genetic Heart Disease Clinics at Royal Prince Alfred Hospital, Sydney, Australia was conducted from March 2015 to November 2015. The methods including study cohort have been reported previously in the setting of overall physical activity behaviours in HCM [7]. Participants were requested to wear a hip-mounted ActiGraph GT3X+ accelerometer (Pensacola, Florida, USA) for a minimum of 7 days during waking hours. The ActiGraph

Results

Valid accelerometer data was available on 63 HCM patients. Cohort characteristics are summarised in Table 1. The majority of participants were male (71%) with a mean age of 48.8 ± 14.9 years and body mass index (BMI) of 27.9 ± 5.1 (i.e. overweight category). Over one third (36.5%) had an implantable cardioverter defibrillator in situ and 54% were on beta-blocker medication. A quarter of participants (25%) had an NYHA class greater than one (NYHA class II, n = 15; NYHA class III, n = 1) and 40% had

Discussion

We suggest that those with LVOTO or NYHA class II–IV take fewer steps per day than those without obstruction or NYHA class I. Based on accelerometry, the current study indicates that measurement of daily step count may be a useful tool to determine exercise capacity and provide an indicator of disease severity in individuals with HCM. At a clinical level, the high specificity for both history of LVOTO and NYHA class II–IV indicate that patients with either of these characteristics may not

Acknowledgements

JS is the recipient of the Elizabeth and Henry-Hamilton Browne Scholarship from the University of Sydney. JI is the recipient of a National Heart Foundation of Australia Future Leader Fellowship (#100833). KB is the recipient of a National Health and Medical Research Council (NHMRC) Principal Research Fellowship (#1042442). CS is the recipient of an NHMRC Practitioner Fellowship (#1059156). This study is funded in part by a Heart Foundation Australia Vanguard Grant (#101056).

No Disclosures

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Cited by (4)

Accelerometer-assessed physical behavior and the association with clinical outcomes in implantable cardioverter-defibrillator recipients: A systematic review
2022, Cardiovascular Digital Health Journal
Citation Excerpt :
Compared to HF patients, ICD carriers walked more steps per day and reached a higher peak performance (a daily average of the highest step rate values).47 Apart from the study by Witham and colleagues,48 there was a significant difference in daily total step count and time spent in moderate-to-vigorous physical activity (MVPA) across NYHA class groups49–51 and a correlation between step count and LVEF was seen.52 Five studies demonstrated that sleep behavior and PA were associated with patient-reported physical function, quality of life, and cognitive function.49,52–55
Current implantable cardioverter-defibrillator (ICD) devices are equipped with a device-embedded accelerometer capable of capturing physical activity (PA). In contrast, wearable accelerometer-based methods enable the measurement of physical behavior (PB) that encompasses not only PA but also sleep behavior, sedentary time, and rest-activity patterns.
This systematic review evaluates accelerometer-based methods used in patients carrying an ICD or at high risk of sudden cardiac death.
Papers were identified via the OVID MEDLINE and OVID EMBASE databases. PB could be assessed using a wearable accelerometer or an embedded accelerometer in the ICD.
A total of 52 papers were deemed appropriate for this review. Out of these studies, 30 examined device-embedded accelerometry (189,811 patients), 19 examined wearable accelerometry (1601 patients), and 3 validated wearable accelerometry against device-embedded accelerometry (106 patients). The main findings were that a low level of PA after implantation of the ICD and a decline in PA were both associated with an increased risk of mortality, heart failure hospitalization, and appropriate ICD shock. Second, PA was affected by cardiac factors (eg, onset of atrial fibrillation, ICD shocks) and noncardiac factors (eg, seasonal differences, societal factors).
This review demonstrated the potential of accelerometer-measured PA as a marker of clinical deterioration and ventricular arrhythmias. Notwithstanding that the evidence of PB assessed using wearable accelerometry was limited, there seems to be potential for accelerometers to improve early warning systems and facilitate preventative and proactive strategies.
Validation of open-source step-counting algorithms for wrist-worn tri-axial accelerometers in cardiovascular patients
2022, Gait and Posture
Citation Excerpt :
Several studies that have linked disease progression and activity levels and/or steps in CV patients already exist. One study in hypertrophic cardiomyopathy patients has found an association between disease severity and daily step count but not activity counts [9]. In addition, number of steps, physical activity and functional mobility have all been shown to be good predictors for hospital readmission or mortality in CV patients [10–13].
Accurate quantification of daily steps in a cardiovascular patient population is of high importance for primary and secondary prevention. While sensor derived step counts have been sufficiently validated for hip-worn devices and commercial wrist-worn devices, there is a lack of knowledge on validity of freely available step counting algorithms for raw acceleration data collected at the wrist.
How accurate are step-counting algorithms for wrist worn tri-axial accelerometers in a cardiac rehabilitation training setting?
Two step counting algorithms (Windowed Peak Detection, Autocorrelation) for tri-axial accelerometers (Axivity AX-3), were tested. Steps were recorded by chest-mounted GoPro video cameras as gold standard. Cardiovascular patients without neurological impairments enrolled in an ambulatory rehabilitation program were recruited. Recordings were performed during one 45–90 min outdoor physical therapy session of which 5-min segments of six movement categories, namely Walking, Running, Nordic, Stairs, Arm Movement [AM] With [+] and Without [-] Walking [W] were identified and analyzed. Mean absolute difference and mean absolute percentage error [MAPE] with regard to true steps measured from video are reported to report accuracy.
Training sessions of 22 patients were recorded and analyzed. Steps were overestimated during AM-W and underestimated during Walking, Running and Stairs. Windowed Peak Detection algorithm was more accurate during AM+W and AM-W and Autocorrelation performed better during Nordic. A MAPE of close or below 10% was achieved by both algorithms for the categories: Walking, Running, Stairs and Nordic.
Both algorithms provided accurate results for estimation of step counts in a controlled setting of a cardiovascular patient population. The quantification of daily number of steps recorded by wrist-worn accelerometers delivering raw data analyzed by freely available algorithms is a cost-effective option for research studies.
Physical Activity, Inactivity and Sleep in Individuals with Hypertrophic Cardiomyopathy
2022, International Journal of Sports Medicine
Objectively measured adherence to physical activity among patients with coronary artery disease: Comparison of the 2010 and 2020 World Health Organization guidelines and daily steps
2022, Frontiers in Cardiovascular Medicine

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Brief CommunicationDaily Step Count as a Simple Marker of Disease Severity in Hypertrophic Cardiomyopathy

Background

Methods

Results

Conclusions

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgements

J Am Coll Cardiol

Lancet

Hypertrophic cardiomyopathy: a systematic review

JAMA

Prevalence of exercise-induced left ventricular outflow tract obstruction in symptomatic patients with non-obstructive hypertrophic cardiomyopathy

Heart

Effect of left ventricular outflow tract obstruction on clinical outcome in hypertrophic cardiomyopathy

N Engl J Med

Health benefits of physical activity: the evidence

CMAJ

Brief Communication
Daily Step Count as a Simple Marker of Disease Severity in Hypertrophic Cardiomyopathy