Baseline characteristics of the patients who underwent randomisation
| Characteristics | Sildenafil (N=10) | Placebo (N=10) | P value |
| Age (mean±SD) | 49.2±10.8 | 48.4±8.4 | 0.68 |
| Body mass index (kg/m2) (mean±SD) | 27.6±5.3 | 26.7±3.3 | 0.91 |
| Sex | |||
| Male (N (%)) | 7 (53.8) | 6 (46.2) | >0.99 |
| Female (N (%)) | 3 (42.9) | 4 (57.1) | |
| Initial manifestation before diagnosing CSFP | |||
| Acute coronary syndrome (N (%)) | 5 (50.0) | 8 (80.0) | 0.35 |
| Chronic stable angina (N (%)) | 5 (50.0) | 2 (20.0) | |
| Canadian cardiovascular society angina class | |||
| II (N (%)) | 4 (40.0) | 6 (60) | 0.84 |
| III (N (%)) | 4 (40.0) | 2 (20.0) | |
| IV (N (%)) | 2 (20.0) | 2 (20.0) | |
| Risk factors | |||
| Hypertension (N (%)) | 3 (30) | 0 | 0.21 |
| Diabetes (N (%)) | 2 (20) | 0 | 0.47 |
| Hypercholesterolaemia (N (%)) | 3 (30) | 3 (30) | >0.99 |
| Smoking (N (%)) | 2 (20) | 4 (40) | 0.62 |
| Family history of coronary artery disease (N (%)) | 4 (40) | 7 (70) | 0.37 |
| Drug history | |||
| Nitroglycerine (N (%)) | 4 (40) | 2 (20) | 0.62 |
| Aspirin (N (%)) | 9 (90) | 8 (80) | >0.99 |
| Statin (N (%)) | 9 (90) | 6 (60) | 0.30 |
| ACEI or ARB (N (%)) | 3 (30) | 0 (0) | 0.21 |
| Calcium channel blockers (N (%)) | 1 (10) | 2 (20) | >0.99 |
| Beta-blockers (N (%)) | 7 (70) | 4 (40) | 0.37 |
| Blood pressure (mm Hg) | |||
| Systolic (mean±SD) | 123±14.8 | 127.6±12.4 | 0.68 |
| Diastolic (mean±SD) | 74.9±12.1 | 76.9±8.3 | 0.48 |
| ECG | |||
| Sinus rhythm (N (%)) | 10 (100) | 10 (100) | >0.99 |
| Rate (beats per minutes) (mean±SD) | 92.9±16.4 | 82.0±18.5 | 0.01 |
| ST depression (N (%)) | 4 (40) | 3 (30) | >0.99 |
| Abnormal T wave (N (%)) | 3 (30) | 6 (60) | 0.37 |
| PR interval (mean±SD) (ms) | 136±20.6 | 142±19.8 | 0.58 |
| QTc interval (mean±SD) (ms) | 410.8±30.7 | 426.2±42.5 | 0.53 |
| Exercise tolerance test | |||
| Positive test (N (%)) | 3 (30) | 3 (30) | >0.99 |
| Duke score (median (IQR)) | 3.0 (0.0–9.0) | 7 (-1.5–9.25) | 0.97 |
| METs (mean±SD) | 9.92±3.1 | 9.5±2.1 | >0.99 |
| 1 min heart rate recovery (mean±SD) | 16±8.4 | 25±8.3 | 0.03 |
| Maximum heart rate (mean±SD) | 149.8±17.8 | 140.7±12.1 | 0.35 |
| Echocardiography | |||
| Left ventricular ejection fraction (mean±SD) | 53.5±3.37 | 54±3.1 | 0.74 |
| Angiography | |||
| Corrected TIMI frame count of LAD (mean±SD) | 56.2±20.7 | 42.7±7.93 | 0.25 |
| TIMI frame count of LCX (Mean±SD) | 54±14.9 | 46.6±10.8 | 0.31 |
| TIMI frame count of RCX (Mean±SD) | 54±12 | 49±19.4 | 0.34 |
ARB, angiotensin receptor blocker; CSFP, coronary slow flow phenomenon; LAD, left anterior descending; LCX, left circumflex; METs, metabolic equivalents; RCX, right circumflex; TIMI, Thrombolysis in Myocardial Infarction.