Coronary Microcirculation in Aortic Stenosis: Pathophysiology, Invasive Assessment, and Future Directions

Table 2

Literature review of hyperemic myocardial resistance with severe aortic stenosis.

Authors	Citation	Normal subjects			Aortic stenosis subjects
		N	HMR	value	N	Mean (mmHg)	AVA (cm^2)	HMR	After TAVI	value	Long term
Doppler flow velocity with HMR in mmHg/(cm/sec) units
Vendrik et al. [35]	JAHA 2020; 9: e015133				13		0.83	2.54	2.18	<0.001†	1.95
Lumley et al. [42]	JACC 2016; 68: 688	30	2.29	0.14	19	57	0.74	2.82
Wiegerinck et al. [36]	Circ CV Int 2015; 8: e002443	28	1.80	0.096	27	43	0.78	2.10	1.83	0.072
Ahmad et al. [37]	JACC CV Int 2018; 11: 2019				30	38	0.68	2.42	2.14	0.03
Bolus thermodilution with HMR in mmHgsec units
Nishi et al. [57]	Coron Artery Dis 2018; 29: 223	30	16.2	0.14	9	54	0.70	20.4
Gutiérrez-Barrios et al. [47]	Int J Cardiol 2017; 236: 370	10	17.8	0.01	36	53		32.7
Stoller et al. [48]	EuroIntervention 2018; 14: 166				40	45 to 58‡	<1.0	26.6§	30.7	0.42

∗ = compares normal versus aortic stenosis subjects.  = for this study, the value refers to both Friedman test comparing baseline, post-TAVI, and long term as well as each pairwise comparison. ‡ = averages reported separately for subjects with (N = 26) and without (N = 14) coronary artery disease, respectively. § = only study to correct HMR using an explicitly measured zero-flow pressure.  = pressure gradient, AVA = aortic valve area, HMR = hyperemic myocardial resistance, N = number of subjects, and TAVI = transcatheter aortic valve implantation.