Table 2.

Comparison of CFR using different methods in reference control groups.

Number of patients	Method	CFR	Reference
17 (HTX)	DI	5.0 ± 0.3*	[11]
26 (HTX)	DI	5.2 ± 1.3*	[12]
18 (young subjects)	PET	4.1 ± 0.9	[13]
22 (elderly subjects)	PET	3.0 ± 0.7	[13]
10	D.TTE	4.5 ± 0.9	[14]
10	PET	4.1 ± 1.0	[15]
10	D.TTE	5.2 ± 1.6	[16]
19	D.TTE	3.7 ± 0.7	[17]
26 (athletes)	D.TTE	5.9 ± 1.0	[17]

* intracoronary papaverine

CFR = coronary flow reserve; DI. = invasive intracoronary Doppler, D.TTE = noninvasive transthoracic Doppler echocardiography, HTX = routine assessment of coronary flow reserve early after heart transplantation