Mit elite plus

Office BP was recorded using the Omron^® MIT ELITE Plus or M10-IT device (Omron Co., Kyoto, Japan). All efforts were made to standardize office BP recordings for each patient including measurement from the same arm at same time of day using the same device by the same person. Caffeine, exercise, and smoking were avoided for at least 30 min prior to the measurement and patients sat quietly in a chair for at least 5 min before recordings.
An appropriately sized cuff was used to ensure the bladder within the BP cuff encircled at least 80% of the arm. BP was measured in both arms and the arm with the higher reading was used for office BP recording. For study defined BP measurements, three sitting BP and heart rate (HR) measurements were recorded, 1–2 min apart. The average of the 2nd and the 3rd measurements have been used for analysis. Standing BP and HR were recorded after 1 min to check the presence of OHTN, defined as office standing minus office seated systolic blood pressure (SBP) ≥ 20 mmHg and/or office standing minus office sitting diastolic blood pressure (DBP) ≥ 10 mmHg at baseline. The presence of any symptoms was not required for the diagnosis of OHTN.

Brachial blood pressure and heart rate readings were measured in the left arm with an appropriately sized cuff using a MIT Elite Plus (Omron, The Netherlands) in a resting seated position. Clinic BP and HR were estimated as the average of the final two of three consecutive readings.
Participants with long COVID underwent a standard transthoracic echocardiogram (EPIQ 7G, Philips, MA, USA). Left ventricular (LV) structure and systolic and diastolic function were assessed using 2D, 3D, and Doppler echocardiography. Full details of the protocol and outcome measures is provided in the Appendix S1 (Section 1.2.1).
In long COVID cases, pulse wave velocity (PWV) was measured in a semi supine position using a Vicorder device (Skidmore Medical, Germany) according to manufacturer guidelines. Three consecutive measurements were acquired (within 0.5 m/s of each other) and averaged. Full protocol details are described in the Appendix S1 (Section 1.2.2).

Heart rate recovery (HRR) was calculated at 1 and 2 min post‐exercise. The 30 s rolling average HR centred around 60 and 120 s of the recovery phase was subtracted from the peak HR measured during exercise. In long COVID cases, the change in BP and HR following a lying to standing maneuver were assessed using a brachial BP cuff (MIT Elite Plus, Omron, The Netherlands) to test for orthostatic hypotension (BP drop of >20 mmHg) and postural orthostatic tachycardia syndrome (POTS) (HR increase of >30 bpm on standing) (Freeman et al., 2011 (link); Schatz et al., 1996 (link)). In long COVID cases, a 5‐min 12‐lead ECG was recorded at rest in the supine position to assess heart rate variability (HRV). Time domain (RMSSD, the root mean square successive NN differences) and frequency domain (LF, low frequency; HF, high frequency; LF normalized; LFHF, ratio of low frequency to high frequency) measures were derived following manufacturer algorithms (CardioPerfect HRV Module 1.6.7.1149, Welch Allyn, USA).