Author + information
- Rupert Williams1,
- Guus de Waard2,
- Satpal Arri3,
- Tiffany Patterson4,
- Howard Ellis3,
- Natalia Briceno5,
- Amedeo Chiribiri3,
- Brian Clapp6,
- Niels van Royen7,
- Divaka Perera8,
- Michael Marber3 and
- Simon Redwood3
- 1St George's Hospital, London, United Kingdom
- 2VU University Medical Centre, Amsterdam, Netherlands
- 3St Thomas' Hospital, London, United Kingdom
- 4King's College London, St Thomas' Hospital, London, United Kingdom
- 5St Thomas' Hospital/King's College London, London, United Kingdom
- 6St Thomas Hospital, London, United Kingdom
- 7Radboud University, Nijmegen, Netherlands
- 8St Thomas' Hospital Campus, King's College London, London, United Kingdom
Cold air inhalation during exercise increases cardiac mortality. The pathophysiology remains unclear, but may reflect adverse changes in microvascular resistance. We compared the accuracy of two intra-coronary measures of microvascular resistance to predict microvascular dysfunction. We then used the best microvascular resistance measure to quantify changes during cold air inhalation, exercise alone and exercise with cold air inhalation.
56 patients (74 arteries: post percutaneous coronary intervention or fractional flow reserve >0.8) had hyperaemic microvascular resistance (hMR) and index of microcirculatory resistance (IMR) compared against: Coronary flow reserve CMR perfusion CMR microvascular obstruction. In a further 55 patients (45 with coronary artery disease), baseline and peak microvascular resistance was measured after 5 minutes of either: Cold air inhalation (-15oC) Cycling Cold air inhalation during cycling.
hMR had better diagnostic accuracy than IMR to predict coronary flow reserve (area under curve (AUC) 0.82 vs. 0.58), CMR perfusion (AUC 0.85 vs. 0.72) and microvascular obstruction (AUC 0.83 vs. 0.72). Cold air inhalation at rest decreased microvascular resistance in patients with normal coronaries but increased microvascular resistance in coronary artery disease patients (p<0.01). In coronary artery disease patients, cycling caused an adaptive decrease in microvascular resistance (p<0.0001), but cold air inhalation during cycling abolished this decrease.
hMR is a better predictor of microvascular dysfunction than IMR. Cold air inhalation causes adverse changes in microvascular resistance in coronary artery disease patients both at rest and during exercise, rendering the heart more susceptible to ischaemia.
IMAGING: FFR and Physiologic Lesion Assessment