Determining the predominant lesion in patients with severe aortic stenosis and coronary stenoses: A multicenter study using intracoronary pressure and flow

Selected in Circulation Cardiovascular Interventions by N. Ryan

Concomitant coronary artery disease (CAD) is frequently found in patients with severe aortic stenosis (AS) undergoing treatment with transcatheter aortic valve implantation (TAVI).

References

Authors

Ahmad Y, Vendrik J, Eftekhari A, Howard JP, Cook C, Rajkumar C, Malik I, Mikhail G, Ruparelia N, Hadjiloizou N, Nijjer S, Al-Lamee R, Petraco R, Warisawa T, Wijntjens GWM, Koch KT, van de Hoef T, de Waard G, Echavarria-Pinto M, Frame A, Sutaria N, Kanaganayagam G, Ariff B, Anderson J, Chukwuemeka A, Fertleman M, Koul S, Iglesias JF, Francis D, Mayet J, Serruys P, Davies J, Escaned J, van Royen N, Götberg M, Juhl Terkelsen C, Høj Christiansen E, Piek JJ, Baan J Jr, Sen S.

Reference

Circ Cardiovasc Interv. 2019 Dec;12(12):e008263

Published

December 2019

Link

Read the abstract

Reviewer

Nicola Ryan

@NicolaRyanI1

Interventional cardiologist / Cardiologist

Aberdeen, United Kingdom

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My Comment

This joint review is part of the PCRonline GLOBAL Journal Club Initiative by selected members of the EAPCI/PCR Journal Club and PCR NextGen, and is based on the underlying idea of “Bringing peers together, exchanging ideas, towards a common standard of care”.

Why this study – the rationale/objective?

Both coronary stenoses and severe aortic stenosis (AS) are known to cause chest pain and dyspnoea due to the microcirculation’s inability to augment blood flow in response to increased demand. In clinical practice differentiating between symptoms from CAD and AS can be difficult. The aim of this study was to identify the predominant lesion (AS or CAD) in patients with severe AS and coronary stenoses, as well as determine a physiological severity at which treating a coronary stenosis with PCI provides an equivalent improvement in microcirculatory function to treating severe AS with TAVI.

How was it executed – the methodology?

Group 1 included 55 patients undergoing TAVI with intermediate coronary lesions determined not to require PCI by the Heart Team.
Group 2 comprised 85 patients with no AS undergoing PCI for intermediate coronary stenoses.
All patients had measurements of coronary pressure, flow and resistance taken at rest and during hyperaemia, pre and post TAVI or PCI using a doppler pressure wire.
Microvascular resistance over the wave free period of diastole was documented as a measure of coronary stenosis (low microvascular resistance had been previously associated with more severe coronary stenosis, and high resistance with a less severe stenosis).
Microvascular reserve, the ratio of hyperaemic microvascular resistance to resting microvascular resistance, was calculated, and used as a measure of improvement in haemodynamics post intervention (TAVI or PCI).

What is the main result?

Microvascular resistance over the wave free period of diastole increased significantly post TAVI (pre 2.71±1.4 mmHg/cms-1 vs. post 3.04±1.6 mmHg/cms-1, p=0.03), with unchanged hyperaemic resistance, due to the improved ability of the microcirculation to augment blood flow in response to demand.
In line with this, microvascular reserve over the wave free period of diastole improved significantly post TAVI (pre 1.88±1.0 vs. post 2.09±0.8, p=0.003).
Post PCI, the microvascular resistance over the wave free period of diastole increased significantly dependant on the baseline iFR value, i.e. the lower iFR was, the greater improvement in microvascular resistance. Of note, post TAVI, the improvement in microvascular resistance was independent of iFR values.
An average improvement in microvascular resistance over the wave free period of diastole of 19.2±0.5% was seen post TAVI. To achieve a 19% improvement in microvascular resistance over the wave free period of diastole post PCI a baseline iFR of 0.74 was calculated to be required.

Critical reading and the relevance for clinical practice

The results of this study show that severe AS behaves in a similar fashion to a coronary stenosis in terms of its effects on the microcirculation. When both coronary stenosis and AS co-exist, treating the AS with TAVI improves but does not normalise microvascular resistance. Comparing the change in microvascular resistance post TAVI to that seen post PCI allows comparisons to be drawn between the treatment effect of TAVI and PCI. Only when the iFR values of a coronary stenosis are less than 0.74, are improvements in microvascular resistance similar to those of TAVI seen with PCI. In terms of clinical practice, this implies that in a patient with severe AS and concomitant CAD, only revascularizing stenoses with a baseline iFR<0.74 would add additional benefits to that expected by TAVI alone.

A note of caution when interpreting these results – one must bear in mind that this was a small study with different baseline patient characteristics in each arm, e.g. mean age was 82 years in the TAVI group and 61 in the PCI group, which, may also have had an impact on microvascular function. Ultimately, a randomized comparison between physiology- and angiography-based revascularization in this specific patient population may be needed to better inform clinical practice.