Table 2.
Baseline characteristics of study population.
| Data are n (%) unless stated. N = 242 (125/117) unless stated. Different denominators due to missing data | |||||||
|---|---|---|---|---|---|---|---|
| Intervention n = 125 |
Control n = 117 |
Total n = 242 |
|||||
| Gender: Male | 51 | 40.8 | 54 | 46.2 | 105 | 43.4 | |
| Age in years/mean (SD) | 40.0 (14.0) | 39.1 (13.5) | 39.6 (13.8) | ||||
| Number of episodes palpitations or pre-syncope in last 24 h/median (IQR) | 1.0 (1.0–3.0) | 1.0 (1.0–3.0) | 1.0 (1.0–3.0) | ||||
| History of presenting episode | Palpitations | 110 | 88.0 | 109 | 93.2 | 219 | 90.5 |
| Pre-syncope | 15 | 12.0 | 8 | 6.8 | 23 | 9.5 | |
| Estimated length of presenting (last) episode | 1 min or less | 19 | 15.2 | 19 | 16.2 | 38 | 15.7 |
| 10 min or less | 31 | 24.8 | 37 | 31.6 | 68 | 28.1 | |
| 1 h or less | 27 | 21.6 | 27 | 23.1 | 54 | 22.3 | |
| More than 1 h | 48 | 38.4 | 34 | 29.1 | 82 | 33.9 | |
| Participants description of symptoms | Anxious | 52 | 41.6 | 50 | 42.7 | 102 | 42.1 |
| Arm or neck pain or tingling | 34 | 27.2 | 33 | 28.2 | 67 | 27.7 | |
| Chest pain or pressure | 51 | 40.8 | 52 | 44.4 | 103 | 42.6 | |
| Dizziness | 62 | 49.6 | 56 | 47.9 | 118 | 48.8 | |
| Faint/Light headed | 73 | 58.4 | 61 | 52.1 | 134 | 55.4 | |
| Pounding | 55 | 44.0 | 56 | 47.9 | 111 | 45.9 | |
| Fluttering | 42 | 33.6 | 38 | 32.5 | 80 | 33.1 | |
| Short of breath | 51 | 40.8 | 49 | 41.9 | 100 | 41.3 | |
| Fast/Racing heart | 77 | 61.6 | 68 | 58.1 | 145 | 59.9 | |
| Skipped/missed heartbeat(s) | 33 | 26.4 | 27 | 23.1 | 60 | 24.8 | |
| Irregular heart beating | 36 | 28.8 | 40 | 34.2 | 76 | 31.4 | |
| How often do they occur? | Never had before | 29 (n = 124) |
23.4 | 29 | 24.8 | 58 (n = 241) |
24.1 |
| Yearly (or even less frequent) | 21 (n = 124) |
16.9 | 27 | 23.1 | 48 (n = 241) |
19.9 | |
| Monthly | 27 (n = 124) |
21.8 | 25 | 21.4 | 52 (n = 241) |
21.6 | |
| Weekly | 18 (n = 124) |
14.5 | 15 | 12.8 | 33 (n = 241) |
13.7 | |
| More than once a week | 29 (n = 124) |
23.4 | 21 | 17.9 | 50 (n = 241) |
20.7 | |
| How do the palpitations start? | Suddenly | 104 (n = 123) |
84.6 | 94/116 | 81.0 | 198 (n = 239) |
82.8 |
| Gradually | 19 (n = 123) |
15.4 | 22/116 | 19.0 | 41 (n = 239) |
17.2 | |
| Can palpitations be provoked? | Yes | 16 (n = 123) |
13.0 | 18 (n = 116) |
15.5 | 34 (n = 239) |
14.2 |
| How do the palpitations end? | Suddenly | 48 (n = 121) |
39.7 | 47 (n = 115) |
40.9 | 95 (n = 236) |
40.3 |
| Gradually | 73 (n = 121) |
60.3 | 68 (n = 115) |
59.1 | 141 (n = 236) |
59.7 | |
| Participant able to end the attacks? | Yes | 19 (n = 123) |
15.4 | 14 | 12.0 | 33 (n = 240) |
13.8 |
| Recent alcohol use? | Yes | 11 | 8.8 | 16 | 13.7 | 27 | 11.2 |
| Recent cocaine or amphetamine use? | Yes | 1 | 0.8 | 0 | 0.0 | 1 | 0.4 |
| Recent (last 7 days) febrile illness? | Yes | 9 | 7.2 | 8 | 6.8 | 17 | 7.0 |
| Past medical history | |||||||
| Previous or known hypertension/ischaemic/coronary/valvular heart disease/failure | Yes | 14 (n = 124) |
11.3 | 20 | 17.1 | 34 (n = 241) |
14.1 |
| Previous or known anaemia or thyrotoxicosis | Yes | 4 (n = 124) |
3.2 | 3 | 2.6 | 7 (n = 241) |
2.9 |
| Drug history – is the patient taking | |||||||
| β agonists | Yes | 7 | 5.6 | 8 | 6.8 | 15 | 6.2 |
| Antimuscarinics/Anticholinergic | Yes | 5 | 4.0 | 2 | 1.7 | 7 | 2.9 |
| Theophylline | Yes | 0 | 0.0 | 1 | 0.9 | 1 | 0.4 |
| Dihydropyridine calcium channel blockers | Yes | 3 | 2.4 | 6 | 5.1 | 9 | 3.7 |
| Class 1 anti-arrhythmics | Yes | 1 | 0.8 | 2 | 1.7 | 3 | 1.2 |
| Drugs that may prolong the QT interval | Yes | 1 | 0.8 | 0 | 0.0 | 1 | 0.4 |