TABLE 1.

Differential Diagnosis and Recommended Testing to Consider for Abnormal Health Metrics From Consumer Wearable Devices

Metric	Differential Diagnosis	Confirmatory Diagnostic Testing to Be Considered	Additional Testing Considerationsa
Low heart rate (resting conditions)	Wearable device heart rate measurement failure Bradyarrhythmia  Sinoatrial node dysfunction, high grade atrioventricular block Sinus bradycardia  Anorexia/malnutrition, CNS disease, hypothermia, hypothyroidism, exercise training, medication effect, sleep apnea, increased vagal tone	12-lead ECG Clinically approved ambulatory rhythm monitor	Bradyarrhythmia  Refer to AHA/ACC guidelines following arrhythmia confirmationb Sinus bradycardia Careful medication history Laboratory studies (BMP, TSH) Sleep study
High heart rate (resting conditions)	Wearable device heart rate motion artifact Tachyarrhythmia  Paroxysmal supraventricular tachycardia, ventricular tachycardia Sinus tachycardia  Anxiety, dehydration, anemia, medication effect (eg, beta-blocker withdrawal, beta agonist), infection, heart failure, hyperthyroidism, pain, POTS, pregnancy, PE, shock, stimulant use, inappropriate sinus tachycardia	12-lead ECG Clinically approved ambulatory rhythm monitor	Tachyarrhythmia  Refer to AHA/ACC guidelines following arrhythmia confirmationb Sinus tachycardia Careful medication history Laboratory studies (BMP, CBC, D-dimer, TSH, iron studies) TTE
Low SpO2 (resting conditions)	Wearable device SpO2 measurement failure High altitude Hypoventilation  Chest wall pathology (eg, kyphoscoliosis), CNS disease, sedatives, hypothyroidism, metabolic alkalosis, OSA, respiratory muscular weakness (eg, ALS) V/Q mismatch or shunt  ARDS, asthma, atelectasis, pulmonary AVM, bronchiectasis, COPD, pulmonary edema (cardiac and noncardiac), ILD, intracardiac shunt, mucus plugging, PE, PNA	Clinically approved pulse oximetry Arterial blood gas	Careful medication history Chest radiography Laboratory studies (D-dimer) PFTs TTE with bubble study
Irregular heart rhythm (resting conditions and during exercise)	Wearable device heart rate measurement failure Wearable device heart rate motion artifact Arrhythmia Respiratory sinus arrhythmia	12-lead ECG Clinically approved ambulatory rhythm monitor	Arrhythmia  Refer to AHA/ACC guidelines following arrhythmia confirmationb Sinus arrhythmia  No further testing recommended
HRV (low)	Wearable device heart rate measurement failure aging Physical deconditioning inadequate recovery/overtraining infection Medication effect Mental stress Poor sleep Systemic illness Toxins (eg, EtOH) Thermal stress (warmer temperatures)	Detailed medical and social history	No further testing recommended
HRR (low)	Wearable device heart rate measurement failure Physical deconditioning Medication effect Systemic illness Tachyarrhythmia	Detailed medical and social history	Exercise ECG with postrecovery monitoring
Peak $\stackrel{.}{\mathrm{V}}{\mathrm{O}}_2$ (low)	Wearable device $\stackrel{.}{\mathrm{V}}{\mathrm{O}}_2$ algorithm inaccuracy Physical deconditioning Cardiopulmonary disease Anemia Skeletal muscular disease (myopathy)	CPET	Laboratory studies (CBC)
High respiratory rate (resting conditions and during exercise)	Wearable device RR motion artifact Anxiety Cardiac disease (arrhythmia, ischemia, heart failure) Diabetic ketoacidosis Anemia Exercise Fever/sepsis Pulmonary disease (asthma, COPD, effusion, ILD, PE) Toxins	Visual assessment and manual assessment of respiratory rate	Chest radiography Laboratory studies (ABG, CBC, CMP, toxicology) PFTs
Low respiratory rate (resting conditions and during exercise)	Wearable device RR measurement failure CNS disease Hypothyroidism Medication effect Sleep apnea Toxins (eg, opiates)	Visual assessment and manual assessment of respiratory rate	Laboratory studies (TSH, toxicology) Sleep study
Sleep (poor sleep)	Wearable device heart rate and/or RR measurement failure Dehydration Medication effect (eg, stimulants) Sleep disorder (eg, restless leg, syndrome, sleep apnea) Stress/anxiety Toxins (eg, EtOH)	Detailed medical and social history	Laboratory studies (iron studies) Sleep study

^aA thorough history and physical examination is recommended as the starting point in the evaluation of all abnormal testing.

^bFor confirmed bradyarrhythmia, refer to the 2018 AHA/ACC/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay.¹⁰² For confirmed tachyarrhythmia, refer to the 2015 AHA/ACC/HRS guideline for the management of adult patients with supraventricular tachycardia¹⁰³ or the 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death¹⁰⁴ or the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation¹⁰⁵/2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation.¹⁰⁶

ABG = arterial blood gas; ARDS = acute respiratory distress syndrome; AVM = arteriovenous malformation; BMP = basic metabolic panel; CMP = comprehensive metabolic panel; CNS = central nervous system; COPD = chronic obstructive pulmonary disease; EtOH = alcohol; ILD = interstitial lung disease; OSA = obstructive sleep apnea; PE = pulmonary embolism; PFT = pulmonary function test; PNA = pneumonia; POTS = postural orthostatic tachycardiac syndrome; RR = respiratory rate; TSH = thyroid stimulating hormone; TTE = transthoracic echocardiography.