Author + information
- Viviany Taqueti,
- Venkatesh Murthy,
- Brendan Everett,
- Sharmila Dorbala,
- Ron Blankstein,
- Masanao Naya,
- Jon Hainer,
- Courtney Foster and
- Marcelo Di Carli
Very low levels of cardiac troponin (Tn) are associated with increased mortality, even among patients without overt obstructive coronary artery disease (CAD). We tested the hypothesis that in pts without overt obstructive CAD, those with detectable Tn will show abnormal coronary flow reserve (CFR, reflecting diffuse atherosclerosis and microvascular dysfunction), and that Tn positivity and abnormal CFR will be associated with adverse clinical outcomes.
We included 650 consecutive pts with chest pain or dyspnea, but without a history of prior CAD, undergoing myocardial perfusion PET imaging showing no evidence of obstructive CAD and normal ejection fraction (≥40%). Myocardial blood flow (MBF, mL/min/g) was quantified at rest and at peak stress. CFR was estimated from the ratio of stress/rest MBF. Serum Tn levels were measured within 14 days prior to PET imaging. Pts were followed for a median of 1.79 years [0.92-2.66] for the occurrence of major adverse clinical events (MACE) including death, myocardial infarction, or late revascularization.
Tn positive pts were older (median age: 65 vs. 61 yrs for Tn negative pts, p<0.001). However, Tn positive and negative pts were balanced with respect to gender, hypertension, dyslipidemia, and diabetes. Compared with Tn negative pts (n=560), those with positive Tn (n=90) had lower peak MBF (1.87 [1.48-2.59] vs 2.27 [1.69-2.89] mL/min/g, p=0.0004) and CFR (1.82 [1.68-1.96] vs. 2.11 [2.06-2.18], p=0.0003). After adjusting for age, sex, race, hypertension, hyperlipidemia, diabetes, smoking, body mass index, and LV mass index, there was a significant inverse association between Tn and CFR (beta −0.24, [95% Cl −0.40 to −0.08], p=0.0029). 55 pts experienced MACE, including 37 deaths. In survival analysis, age (HR 1.0 [1.01-1.07]), male gender (HR 2.28 [1.25-4.17]), tobacco use (HR 2.77 [1.26-6.06]), positive Tn (HR 2.0 [1.12-3.79]), and higher CFR (HR 0.43 [0.25-0.73]) were significantly associated with MACE.
In pts without overt CAD, a detectable Tn is associated with reduced coronary vascular reactivity. Both Tn positivity and impaired CFR are associated with worse clinical outcomes.
Poster Sessions, Expo North
Saturday, March 09, 2013, 10:00 a.m.-10:45 a.m.
Session Title: Cardiac PET: Towards Flow Quantification and Novel Applications
Abstract Category: 21. Imaging: Nuclear
Presentation Number: 1139-325
- 2013 American College of Cardiology Foundation