Exhibit 99

Form 4 Joint Filer Information

Name:	ATV Associates VII, L.L.C.

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	ATV Associates VII, L.L.C.


	By:	/s/ Michael A. Carusi
		Michael A. Carusi, Managing Director

Name:	Advanced Technology Ventures VII (B), L.P.

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	Advanced Technology Ventures VII (B), L.P.
	By: ATV Associates VII, L.L.C.
	Its: General Partner


	By:	/s/ Michael A. Carusi
		Michael A. Carusi, Managing Director

Name:	Advanced Technology Ventures VII (C), LP

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	Advanced Technology Ventures VII (C), LP
	By: ATV Associates VII, L.L.C.
	Its: General Partner


	By:		/s/ Michael A. Carusi
			Michael A. Carusi, Managing Director

Name:	ATV Entrepreneurs VII, L.P.

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	ATV Entrepreneurs VII, L.P.
	By: ATV Associates VII, L.L.C.
	Its: General Partner


	By:	/s/ Michael A. Carusi
		Michael A. Carusi, Managing Director

Name:	ATV Associates VI, L.L.C.

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	ATV Associates VI, L.L.C.


	By:		/s/ Michael A. Carusi
			Michael A. Carusi, Managing Director

Name:	Advanced Technology Ventures VI, L.P.

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	Advanced Technology Ventures VI, L.P.
	By: ATV Associates VI, L.L.C.
	Its: General Partner


	By:	/s/ Michael A. Carusi
		Michael A. Carusi, Managing Director

Name:	ATV Entrepreneurs VI, L.P.

Address:	Attn: Michael A. Carusi
	1000 Winter Street, Suite 3700
	Waltham, MA 02451

Designated Filer:	Advanced Technology Ventures VII, L.P.

Issuer & Ticker Symbol:	XTENT, Inc. (XTNT)

Date of Event
Requiring Statement:	February 6, 2007


Signature:	ATV Entrepreneurs VI, L.P.
	By: ATV Associates VI, L.L.C.
	Its: General Partner


	By:	/s/ Michael A. Carusi
		Michael A. Carusi, Managing Director

XTENT INC 4