ABSTRACT
OBJECTIVE: We sought to assess the incremental prognostic value of quantitative plaque characterization beyond established CT risk scores. BACKGROUND: Several plaque characteristics detectable by coronary computed tomographic angiography (coronary CTA) are thought to be indicative of vulnerable plaques and subsequent cardiac events, particularly low attenuation plaque volume (LAPV), positive remodeling and the napkin-ring sign which is high density vascular adhesion with a small center of low density. It is unknown how quantitative plaque assessment can contribute to the long-term prediction of cardiovascular events in relation to established CT risk scores such as the calcium score or Segment Stenosis Score (SSS). METHODS: In 1168 consecutive patients with suspected coronary artery disease (CAD), calcium score measurement and coronary plaque characterization was performed comprising the presence of calcified, non-calcified, and partially calcified plaques on a per-segment basis. In all non-calcified or partially calcified plaques, semi-automated plaque analysis was performed to quantify low attenuation plaque volume (density <30 HU), total non-calcified plaque volume (<150 HU, TNCPV) and remodeling index. The presence of the napkin-ring sign was assessed visually. The study endpoint was the occurrence of major adverse cardiac events (MACE), a composite of cardiac death, myocardial infarction and coronary revascularization more than 90 days after coronary CTA. RESULTS: During a clinical follow up of 5.7 years, MACE was observed in 46 patients (3.9%). All plaque characteristics were associated with MACE. The strongest association was observed for LAPV (HR 1.12, p < 0.0001). LAPV showed incremental prognostic value in a stepwise multivariable model including the Morise Score for clinical risk, calcium score and SSS (p = 0.036). CONCLUSION: LAPV, TPV, PR and presence of the napkin-ring sign are predictors of MACE independently of clinical risk presentation. LAPV carries slight additional prognostic information beyond the calcium score and conventional coronary CTA analysis. It may therefore improve risk prediction after CT imaging.
Subject(s)
Computed Tomography Angiography , Coronary Angiography/methods , Coronary Artery Disease/diagnostic imaging , Coronary Vessels/diagnostic imaging , Multidetector Computed Tomography , Plaque, Atherosclerotic , Vascular Calcification/diagnostic imaging , Aged , Chi-Square Distribution , Coronary Artery Disease/complications , Coronary Artery Disease/mortality , Coronary Artery Disease/therapy , Disease Progression , Disease-Free Survival , Female , Follow-Up Studies , Humans , Kaplan-Meier Estimate , Male , Middle Aged , Multivariate Analysis , Myocardial Infarction/etiology , Myocardial Revascularization , Predictive Value of Tests , Proportional Hazards Models , Prospective Studies , Retrospective Studies , Risk Assessment , Risk Factors , Rupture, Spontaneous , Time Factors , Vascular Calcification/complications , Vascular Calcification/mortality , Vascular Calcification/therapy , Vascular RemodelingABSTRACT
Area at risk (AAR) is an important parameter for the assessment of the salvage area after revascularization in acute myocardial infarction (AMI). By combining AAR assessment by T2-weighted imaging and scar quantification by late gadolinium enhancement imaging cardiovascular magnetic resonance (CMR) offers a promising alternative to the "classical" modality of Tc99m-sestamibi single photon emission tomography (SPECT). Current T2 weighted sequences for edema imaging in CMR are limited by low contrast to noise ratios and motion artifacts. During the last years novel CMR imaging techniques for quantification of acute myocardial injury, particularly the T1-mapping and T2-mapping, have attracted rising attention. But no direct comparison between the different sequences in the setting of AMI or a validation against SPECT has been reported so far. We analyzed 14 patients undergoing primary coronary revascularization in AMI in whom both a pre-intervention Tc99m-sestamibi-SPECT and CMR imaging at a median of 3.4 (interquartile range 3.3-3.6) days after the acute event were performed. Size of AAR was measured by three different non-contrast CMR techniques on corresponding short axis slices: T2-weighted, fat-suppressed turbospin echo sequence (TSE), T2-mapping from T2-prepared balanced steady state free precession sequences (T2-MAP) and T1-mapping from modified look locker inversion recovery (MOLLI) sequences. For each CMR sequence, the AAR was quantified by appropriate methods (absolute values for mapping sequences, comparison with remote myocardium for other sequences) and correlated with Tc99m-sestamibi-SPECT. All measurements were performed on a 1.5 Tesla scanner. The size of the AAR assessed by CMR was 28.7 ± 20.9 % of left ventricular myocardial volume (%LV) for TSE, 45.8 ± 16.6 %LV for T2-MAP, and 40.1 ± 14.4 %LV for MOLLI. AAR assessed by SPECT measured 41.6 ± 20.7 %LV. Correlation analysis revealed best correlation with SPECT for T2-MAP at a T2-threshold of 60 ms (ms) (slope = 0.99, Pearson's r = 0.94), and for MOLLI at T1-threshold of 1,075 ms (slope 0.86, r = 0.91, Pearson's r = 0.45). For the assessment of AAR in AMI, the novel T2-mapping technique correlates best with SPECT size, T1-mapping with MOLLI and standard T2-weighted imaging showed similar good correlations.
