Hiroto Harigaya

Computed tomographic angiography characteristics of atherosclerotic plaques subsequently resulting in acute coronary syndrome.

OBJECTIVES In a computed tomographic (CT) angiography study, we identified the characteristics of atherosclerotic lesions that were associated with subsequent development of acute coronary syndrome (ACS). BACKGROUND The CT characteristics of culprit lesions in ACS include positive vessel remodeling (PR) and low-attenuation plaques (LAP). These 2 features have been observed in the lesions that have already resulted in ACS, but their prospective relation to ACS has not been previously described. METHODS In 1,059 patients who underwent CT angiography, atherosclerotic lesions were analyzed for the presence of 2 features: PR and LAP. The remodeling index, and plaque and LAP areas and volumes were calculated. The plaque characteristics of lesions resulting in ACS during the follow-up of 27 +/- 10 months were evaluated. RESULTS Of the 45 patients showing plaques with both PR and LAP (2-feature positive plaques), ACS developed in 10 (22.2%), compared with 1 (3.7%) of the 27 patients with plaques displaying either feature (1-feature positive plaques). In only 4 (0.5%) of the 820 patients with neither PR nor LAP (2-feature negative plaques) did ACS develop. None of the 167 patients with normal angiograms had acute coronary events (p < 0.001). ACS was independently predicted by PR and/or LAP (hazard ratio: 22.8, 95% confidence interval: 6.9 to 75.2, p < 0.001). Among 2- or 1-feature positive segments, those resulting in ACS demonstrated significantly larger remodeling index (126.7 +/- 3.9% vs. 113.4 +/- 1.6%, p = 0.003), plaque volume (134.9 +/- 14.1 mm(3) vs. 57.8 +/- 5.7 mm(3), p < 0.001), LAP volume (20.4 +/- 3.4 mm(3) vs. 1.1 +/- 1.4 mm(3), p < 0.001), and percent LAP/total plaque area (21.4 +/- 3.7 mm(2) vs. 7.7 +/- 1.5 mm(2), p = 0.001) compared with segments not resulting in ACS. CONCLUSIONS The patients demonstrating positively remodeled coronary segments with low-attenuation plaques on CT angiography were at a higher risk of ACS developing over time when compared with patients having lesions without these characteristics.

Serial Coronary CT Angiography–Verified Changes in Plaque Characteristics as an End Point: Evaluation of Effect of Statin Intervention

OBJECTIVES This study sought to assess, by serial computed tomography angiography (CTA), the effect of statin treatment on coronary plaque morphology. BACKGROUND In addition to the assessment of luminal stenosis, CTA also allows characterization of plaque morphology. Large, positively remodeled plaques with large necrotic cores have been reported as indicators of plaque instability. METHODS CTA was performed in 32 patients (26 men, ages 64.3 +/- 8.5 years). Of these, 24 received fluvastatin after the baseline study; 8 subjects who refused statin treatment were followed as the control subjects. Serial imaging was performed after a median interval of 12 months. All vessels were examined in every subject, and a 10-mm-long segment was identified for comparison before and after intervention. Total plaque volume, low attenuation plaque (LAP) volume, lumen volume, and remodeling index were calculated. RESULTS In the statin-treated patients, the total plaque volume (92.3 +/- 37.7 vs. 76.4 +/- 26.5 mm(3), p < 0.01) and LAP volume (4.9 +/- 7.8 vs. 1.3 +/- 2.3 mm(3), p = 0.01) were significantly reduced over time; however, there was no change in the lumen volume (63.9 +/- 25.3 vs. 65.2 +/- 26.2 mm(3), p = 0.59). On the other hand, no change was observed in the CTA characteristics in the control subjects, including total plaque volume (94.4 +/- 21.2 vs. 98.4 +/- 28.6 mm(3), p = 0.48), LAP volume (2.1 +/- 3.0 vs. 2.3 +/- 3.6 mm(3), p = 0.91), and lumen volume (80.5 +/- 20.7 vs. 75.0 +/- 16.3 mm(3), p = 0.26). The plaque volume change (-15.9 +/- 22.2 vs. 4.0 +/- 14.0 mm(3), p = 0.01) and LAP volume change (-3.7 +/- 7.0 vs. 0.2 +/- 1.5 mm(3), p < 0.01) were significantly greater in the statin than the control group. The lumen volume (1.3 +/- 15.6 vs. -5.5 +/- 13.1 mm(3), p = 0.24) and remodeling index (-2.4 +/- 6.8% vs. -0.3 +/- 6.5%, p = 0.53) did not show the significant differences between the 2 groups. The decrease in the plaque volume was due to reduction in the LAP volume (R = 0.83, p < 0.01), and was not related to any changes in the lumen volume (R = 0.21, p = 0.24). CONCLUSIONS This preliminary study suggests that serial CTA evaluation of coronary plaques allows for the assessment of interval change in the plaque morphology. Statin treatment results in decreases in the plaque and necrotic core volume. The features known to be associated with plaque instability.

Original ResearchSerial Coronary CT Angiography–Verified Changes in Plaque Characteristics as an End Point: Evaluation of Effect of Statin Intervention

OBJECTIVES This study sought to assess, by serial computed tomography angiography (CTA), the effect of statin treatment on coronary plaque morphology. BACKGROUND In addition to the assessment of luminal stenosis, CTA also allows characterization of plaque morphology. Large, positively remodeled plaques with large necrotic cores have been reported as indicators of plaque instability. METHODS CTA was performed in 32 patients (26 men, ages 64.3 +/- 8.5 years). Of these, 24 received fluvastatin after the baseline study; 8 subjects who refused statin treatment were followed as the control subjects. Serial imaging was performed after a median interval of 12 months. All vessels were examined in every subject, and a 10-mm-long segment was identified for comparison before and after intervention. Total plaque volume, low attenuation plaque (LAP) volume, lumen volume, and remodeling index were calculated. RESULTS In the statin-treated patients, the total plaque volume (92.3 +/- 37.7 vs. 76.4 +/- 26.5 mm(3), p < 0.01) and LAP volume (4.9 +/- 7.8 vs. 1.3 +/- 2.3 mm(3), p = 0.01) were significantly reduced over time; however, there was no change in the lumen volume (63.9 +/- 25.3 vs. 65.2 +/- 26.2 mm(3), p = 0.59). On the other hand, no change was observed in the CTA characteristics in the control subjects, including total plaque volume (94.4 +/- 21.2 vs. 98.4 +/- 28.6 mm(3), p = 0.48), LAP volume (2.1 +/- 3.0 vs. 2.3 +/- 3.6 mm(3), p = 0.91), and lumen volume (80.5 +/- 20.7 vs. 75.0 +/- 16.3 mm(3), p = 0.26). The plaque volume change (-15.9 +/- 22.2 vs. 4.0 +/- 14.0 mm(3), p = 0.01) and LAP volume change (-3.7 +/- 7.0 vs. 0.2 +/- 1.5 mm(3), p < 0.01) were significantly greater in the statin than the control group. The lumen volume (1.3 +/- 15.6 vs. -5.5 +/- 13.1 mm(3), p = 0.24) and remodeling index (-2.4 +/- 6.8% vs. -0.3 +/- 6.5%, p = 0.53) did not show the significant differences between the 2 groups. The decrease in the plaque volume was due to reduction in the LAP volume (R = 0.83, p < 0.01), and was not related to any changes in the lumen volume (R = 0.21, p = 0.24). CONCLUSIONS This preliminary study suggests that serial CTA evaluation of coronary plaques allows for the assessment of interval change in the plaque morphology. Statin treatment results in decreases in the plaque and necrotic core volume. The features known to be associated with plaque instability.

Characteristics of plaque progression detected by serial coronary computed tomography angiography

We previously reported that serial coronary computed tomography angiography (CTA) had a potential to evaluate the interval change of plaque morphology of coronary arteries. The aim of this study was to evaluate variables associated with the plaque progression by serial CTA. We included 148 patients (age 66.3 ± 9.8 years, male 81.1 %, median scan interval 12 months) with coronary artery disease undergoing serial CTA. Each coronary artery was compared visually between baseline and follow-up CTA to detect plaque progression. Baseline characteristics between progression and nonprogression patients did not demonstrate any significant differences. Logistic analysis revealed that only low-density lipoprotein cholesterol (LDL-C) ≥100 mg/dl at follow-up was associated with plaque progression (odds ratio 2.59, 95 % confidence interval 1.12–6.34, P = 0.0263). Cutoff value of LDL-C for plaque progression at follow-up was 103.0 mg/dl based on receiver-operator characteristic curves analyses. Of the 36 progressive lesions in 32 patients, plaque composition at baseline included 13 lesions (36.1 %) of noncalcified plaque, 1 lesion (2.8 %) of calcified plaque, 12 lesions (33.3 %) of partially calcified plaque, and the remaining 10 lesions (27.8 %) had no plaque at baseline and revealed de novo plaques at follow-up. There were 9 lesions (25 %) with high-risk plaque (HRP) characteristics at baseline and 18 lesions (50 %) with HRP at follow-up. Plaque progression of coronary arteries by serial CTA was associated with LDL-C ≥100 mg/dl at follow-up regardless of baseline LDL-C level. There was no specific finding to predict plaque progression on the baseline plaque characteristics.

Beat-to-beat variability of T-wave amplitude for the risk assessment of ventricular tachyarrhythmia in patients without structural heart disease

AIMS Increased temporal repolarization lability, assessed by beat-to-beat variability of T-wave amplitude (TAV), has been shown to be associated with ventricular tachyarrhythmia in patients with a variety of clinical conditions. The aim of this study was to test the ability of TAV to identify patients presenting with malignant ventricular arrhythmia and to predict subsequent occurrences. METHODS AND RESULTS We studied 20 consecutive patients (age 42 ± 15 years, mean ± standard deviation) presenting with ventricular tachyarrhythmia who did not have substantial underlying heart disease and compared them with 40 age- and sex-matched control subjects. The TAV was determined by Holter recording (Ela Medical). Patients with ventricular tachyarrhythmia had a higher maximum value of TAV (max TAV: 38 ± 18 vs. 22 ± 15 μV, P < 0.001) than did the controls. The sensitivity and specificity of max TAV > 22.4 μV for detecting the occurrence of ventricular tachyarrhythmia were 77 and 90%, respectively. During a mean follow-up period of 23 months, three patients had relapses of ventricular tachyarrhythmia. Patients with a recurrence of ventricular tachyarrhythmia had a trend towards a higher max TAV as compared with those who had ventricular tachyarrhythmia but did not relapse (56 ± 23 vs. 36 ± 16 μV, P = 0.061). CONCLUSION Our results suggest that Holter-derived TAV might be associated with the occurrence and recurrence of ventricular tachyarrhythmia in patients without structural heart disease. Prospective validation will be necessary to assess the potential diagnostic value of the TAV in a large general population.

A combination of anatomical and functional evaluations improves the prediction of cardiac event in patients with coronary artery bypass.

Objective To study the usefulness of combined risk stratification of coronary CT angiography (CTA) and myocardial perfusion imaging (MPI) in patients with previous coronary-artery-bypass grafting (CABG). Design A retrospective, observational, single centre study. Setting and patients 204 patients (84.3% men, mean age 68.7±7.6) undergoing CTA and MPI. Main outcome measures CTA defined unprotected coronary territories (UCT; 0, 1, 2 or 3) by evaluating the number of significant stenoses which were defined as the left main trunk ≥50% diameter stenosis, other native vessel stenosis ≥70% or graft stenosis ≥70%. Using a cut-off value with receiver-operating characteristics analysis, all patients were divided into four groups: group A (UCT=0, summed stress score (SSS)<4), group B (UCT≥1, SSS<4), group C (UCT=0, SSS≥4) and group D (UCT≥1, SSS≥4). Results Cardiac events, as a composite end point including cardiac death, non-fatal myocardial infarction, unstable angina requiring revascularisation and heart-failure hospitalisation, were observed in 27 patients for a median follow-up of 27.5 months. The annual event rates were 1.1%, 2%, 5.7% and 12.9% of patients in groups A, B, C and D, respectively (log rank p value <0.0001). Adding UCT or SSS to a model with significant clinical factors including left ventricular ejection fraction, time since CABG and Euro SCORE II improved the prediction of events, while adding UCT and SSS to the model improved it greatly with increasing C-index, net reclassification improvement and integrated discrimination improvement. Conclusions The combination of anatomical and functional evaluations non-invasively enhances the predictive accuracy of cardiac events in patients with CABG.

Association between clinical outcome and antiarrhythmic treatment in heart failure patients who have atrial fibrillation upon admission to the hospital.

BACKGROUND Atrial fibrillation (AF) and heart failure (HF) are associated with significant mortality and morbidity. We sometimes encounter patients who have AF upon admission to the hospital, but it spontaneously converts to sinus rhythm within several days (i.e. converter). PURPOSE We examined the association between the outcome and types of strategy for AF treatment in converters. METHODS From January 2000 to December 2005, we identified 95 converters (age 69 ± 12 years) presenting with worsening HF and AF upon admission, in which sinus rhythm was restored within 7 days without either electrical or pharmacological cardioversion. The patients were classified into three groups according to the antiarrhythmic drug (AAD) therapy used: class I AAD, class III AAD, and rate-control drug. The patients were followed for 36 ± 23 months. RESULTS The left ventricular ejection fraction (LVEF) significantly improved with conversion to sinus rhythm (38 ± 14% vs. 47 ± 13%, p<0.05). Those receiving class I AAD had a trend toward a well-preserved LVEF (50 ± 13%, n=35) as compared to those receiving class III AAD (43 ± 12%, n=24) or rate-control drug (47 ± 14%, n=36). In the patients receiving class I AAD, the rate of all-cause death increased 1.9-fold (p=0.009) compared to those receiving class III AAD, and 1.7-fold (p=0.010) compared to those taking rate-control drug. A hospitalization for HF was observed in 49 (52%) patients, however there was no significant difference in the rate of hospitalization among the three groups (p=0.890). Those receiving rate-control drugs had a 50% lower rate of the development of persistent AF than those taking class III AAD (p=0.019). CONCLUSIONS A rate-control strategy should be the primary approach for converters to reduce mortality and development of persistent AF.