Table 2.
Summary of human studies examining exercise-induced changes in collateral flow through the measurement of the collateral flow index.
| Study | Population | Design | Duration | Intervention | Control | Outcomes | Results |
|---|---|---|---|---|---|---|---|
| Zbinden et al., 2004 [32] | n =1 male Age 46 years Healthy amateur long-distance runner |
Case study | 3 years | Angiography performed during 3 phases of endurance training: 1 = Baseline 2 = Intermediate 3 = High |
N/A | Echocardiogram, angiogra-phy, CPET, CFR, CFI |
Left ventricular ejection fraction increased from phase 1 to phase 2 but dropped below baseline levels during phase 3. Peak exercise capacity (W) increased during every subsequent phase. VO2 (ml/min/kg) max increased during every subsequent phase. CFR increased during every subsequent phase. CFI increased from phase 2 to phase 3. |
| Zbinden et al., 2007 [33] | n = 40 (35 male / 5 female) Mean age 61 years Referred for coronary angiography |
Retrospective cohort study | 3 months | Cardiac Rehabilitation (jogging / cycling) 3x per week for >60 minutes at a target heart rate of 80% heart rate at VO2 max. | A retrospective sedentary group that did not adhere to prescribed exercise programme. | Angio-graphy, CFI, CPET | CFI in the occluded vessel significantly increased in the exercise group (p < 0.03). CFI in the normal vessel significantly increased in the exercise group (p < 0.0002). Significantly correlation between change in CFI and VO2 max (p < 0.007) in the exercise group. |
| Togni et al., 2010 [36] | n = 30 (28 men / 2 women) Mean age 59 years Chronic stable, non-occlusive CAD |
Intra-individual comparison randomised crossover study | N/A | CFI comparatively measured during exercise and rest for each patient. | N/A | CFI, angiogram |
CFI increased significantly from rest to peak exercise (p < 0.0002). |
| Lin et al., 2012 [37] | n = 65 Mean age 60.2 years Single vessel CAD undergoing PCI |
RCT | N/A | CFI during 1 minute of isometric handgrip exercise (50% maximal voluntary contraction). | CFI at rest. | CFI, angiogram |
∆CFI (CFI post occlusion – CFI pre occlusion) significantly increased in the exercising group (p < 0.01). |
| Möbius-Winkler et al., 2016 [34] | n = 60 (45 men / 15 women) Median age 64 years Significant CAD (FFR ≤ 0.75) |
Open-label RCT | 4 weeks | High intensity versus moderate-intensity training versus usual care . | Usual care | CPET, CFI, angiogram |
CFI increased significantly for both exercising groups when compared with usual care (high-intensity p= 0.005, moderate-intensity p= 0.004) VO2 peak increased significantly for both exercising groups (high-intensity p= 0.036, moderate-intensity p= 0.008). |
Abbreviations: CAD: Coronary Artery Disease; CFR: Coronary Flow Reserve; CFI: Collateral Flow Index; CPET: Cardiopulmonary Exercise Test; FFR: Fractional Flow Reserve; HIT: High Intensity Interval Training; PCI: Percutaneous Coronary Intervention; RCT: Randomised Control Trial.