Sixty-Four-Section Cardiac Computed Tomography in Mechanical Prosthetic Heart Valve Dysfunction: Thrombus or Pannus.

BACKGROUND: Distinguishing pannus and thrombus in patients with prosthetic valve dysfunction is essential for the selection of proper treatment. We have investigated the utility of 64-slice multidetector computed tomography (MDCT) in distinguishing between pannus and thrombus, the latter amenable to thrombolysis. METHODS AND RESULTS: Sixty-two (23 men, mean age 44±14 years) patients with suspected mechanical prosthetic valve dysfunction assessed by transesophageal echocardiography were included in this prospective observational trial. Subsequently, MDCT was performed before any treatment was started. Periprosthetic masses were detected by MDCT in 46 patients, and their attenuation values were measured as Hounsfield Units (HU). Patients underwent thrombolysis unless contraindicated, and those with a contraindication or failed thrombolysis underwent surgery. A mass which was completely lysed or surgically detected as a clot was classified as thrombus, whereas a mass which was surgically detected as tissue overgrowth was classified as pannus. A definitive diagnosis could be achieved in 37 patients with 39 MDCT masses (22 thrombus and 17 pannus). The mean attenuation value of 22 thrombotic masses was significantly lower than that in 17 pannus (87±59 versus 322±122; P<0.001). Area under the receiver operating characteristic curve was 0.96 (95% confidence interval: 0.91-0.99; P<0.001), and a cutoff point of HU≥145 provided high sensitivity (87.5%) and specificity (95.5%) in discriminating pannus from thrombus. Complete lysis was more common for masses with HU<90 compared with those with HU 90 to 145 (100% versus 42.1%; P=0.007). CONCLUSIONS: Sixty-four slice MDCT is helpful in identifying masses amenable to thrombolysis in patients with prosthetic valve dysfunction. A high (HU≥145) attenuation suggests pannus overgrowth, whereas a lower value is associated with thrombus formation. A higher attenuation (HU>90) is associated with reduced lysis rates.

Acute myocardial infarction during thrombolysis of mechanical aortic valve thrombosis associated with heparin-induced thrombocytopenia.

We report a case of a 60-year-old man with obstructive aortic prosthetic valve thrombosis (APVT). He was treated with low-dose (25 mg) slow infusion (6 hours) of intravenous tissue plasminogen activator (t-PA), and he suffered acute anterior myocardial infarction (MI) at the fourth hour of t-PA infusion. Infusion was kept on, and coronary reperfusion and successful lysis of APVT were achieved. Intravenous unfractionated heparin (UFH) was then started, however, on the third day following heparin treatment, heparin-induced thrombocytopenia (HIT) was recognized by a drop in the platelet count and rethrombosis of the prosthetic valve. Although no nonheparin anticoagulant was available, intravenous continuous infusion of streptokinase (SKZ) 250,000 U per day was administered for 5 days followed by transition to warfarin therapy. Successful lysis of the APVT was again achieved with this regimen and the patient was discharged after uneventful recovery. The patient remained well at 6 months and 1 year follow-up.

Evaluation of myocardial bridges with 64-slice computed tomography coronary angiography.

OBJECTIVE: The aim of this study is to report the characteristics of myocardial bridging (MB) using 64-slice computed tomography and to demonstrate the association between atherosclerotic coronary artery disease (CAD) and MB. METHODS AND RESULTS: In 990 consecutive patients who underwent multi-slice computed tomography (MSCT) coronary angiography for suspected or known coronary artery disease, myocardial bridge evaluation was performed with axial, curved multiplanar reconstruction and three-dimensional volume-rendered images. 265 bridged segments were identified in 223 (22.5%) patients. Multiple MBs on left coronary arteries were found in 41 patients. Most of the MBs were in the LAD (62.6%), followed by the obtuse marginal artery (14.7%) and diagonal artery (14.3%). The average length of MBs was 14 +/- 7 mm, and the average depth was 1.6 +/- 11 mm. No significant difference was observed between patients with and without MB on the middle LAD in respect of age, gender, prevalence of diabetes, hyperlipidaemia, hypertension, current smoking and prevalence of atherosclerotic plaques at the proximal LAD. On the other hand, prevalence of atherosclerotic plaques at the distal LAD were significantly lower in patients with MB on the middle LAD (3.5% vs. 19.7%, P: 0.0001). CONCLUSIONS: The presence and morphological characteristics of MB and its relation with atherosclerotic plaques in the involved coronary artery can be comprehensively analysed with 64-slice computed tomography coronary angiography. Atherosclerosis is a common finding in segments proximal to MB, but the prevalence of plaques in equivalent segments (proximal LAD in our study) is not higher than in patients under similar coronary artery disease risk and without MB. On the other hand, prevalence of atherosclerotic plaques at the distal LAD was significantly lower in our patients with MB on the middle LAD. Finally, we suggest that rather than causing proximal atherosclerosis, MB might have a more important role in the protection of distal segments of the bridged arteries from atherosclerosis.

Mechanical mitral valve thrombosis and giant left atrial thrombus: comparison of transesophageal echocardiography and 64-slice multidetector computed tomography.

We report on the use of multidetector computed tomography (MDCT) in the diagnosis of prosthetic heart valve thrombosis and a giant left atrial (LA) thrombus extending into the LA appendage (LAA), in comparison with findings of transesophageal echocardiography (TEE). A 52-year-old woman with an eight-year history of mechanical mitral valve (MMV) replacement presented with progressive dyspnea. The electrocardiogram (ECG) showed atrial fibrillation. Transesophageal echocardiography showed severely increased MMV gradients and decreased MMV area. Two thrombi were identified on the atrial aspect of the MMV, one restricting the motion of the lateral leaflet, and the other localized on the septal side of the valve ring. Two other thrombi were also visualized, one in the LA and the other in the LAA, measuring 4.3 x 1.3 cm and 2.1 x 1 cm, respectively. ECG-gated 64-slice contrast-enhanced MDCT depicted a thrombus, involving both atrial and ventricular aspects of the MMV, and also a giant thrombus, 8.3 x 2.4 cm in size, in the LA extending into the LAA. The patient underwent redo-mitral valve replacement, LA thrombectomy, and LAA ligation, and was discharged uneventfully. The size and localization of thrombi in the LA and on the explant MMV matched to the findings of MDCT. In this case, MDCT was superior to TEE in showing the precise nature of both MMV thrombosis and the integrated thrombus involving the LA and LAA.

Prevalence of left main coronary artery disease among patients referred to multislice computed tomography coronary examinations.

We have evaluated the prevalence of left main coronary artery disease (LMCAD) among patients referred to multislice computed tomography (MSCT) coronary angiography examinations. The study Group comprised of 1,000 consecutive patients (750 male and 250 female; mean age 53+/-12 years) who underwent successful 64-slice MSCT examinations. Left main coronary artery (LMCA) was classified into three Groups: normal LMCA; nonsignificant LMCAD with coronary plaques resulting in obstructions 50%. We have found that 24 patients (2.4%) had significant LMCAD. Additional 200 patients (20%) had nonsignificant LMCAD. Univariate analysis revealed that LMCAD was associated with age, male gender, diabetes, hypertension, hyperlipidemia, typical symptoms, history of previous myocardial infarction and previous percutaneous coronary intervention. Only age and male gender were found as independent predictors for LMCAD in multivariate analysis (P < 0.001 and P = 0.001, respectively,). Angiographic follow-up was avaliable for the 24 patients with significant LMCAD, and conventional coronary angiography confirmed the presence of significant LMCAD in all of these patients. Significant LMCAD was found in 2.4% of the 1,000 patients referred to 64-slice MSCT examinations. Age and male gender were the independent predictors for LMCAD.

Diagnostic performance of 64-slice computed tomography coronary angiography to detect significant coronary artery stenosis.

OBJECTIVE: We aimed to determine the diagnostic accuracy of 64-slice multi-slice computed tomography (MSCT) to detect significant coronary artery stenosis with comparison to conventional coronary angiography (CCA). METHODS: In 100 patients (70 men, average age 58 +/- 10 years and age range 31-75 years) scheduled to have conventional coronary angiography, MSCT was performed before catheterization (within 2 months). All patients were in sinus rhythm, able to hold breath for 15 seconds, and had serum creatinine levels < 1.5 mg/dl. MSCT scans were analysed by a radiologist and a cardiologist. Sensitivity, specificity, positive and negative predictive values for the detection of significant stenoses by MSCT in comparison with CCA were calculated on patient, vessel, and segmental bases. RESULTS: 64-slice computed tomography is able to detect significant coronary artery stenosis on a segmental basis with a sensitivity of 88% and specificity of 99% when compared with CCA. All patients with significantly stenotic coronary artery disease are correctly diagnosed. The presence of significant stenosis was correctly diagnosed by MSCT in 126 of 144 segments. Twelve non-significant lesions on CCA were overestimated by MSCT. On vessel-based analysis, the sensitivity and specificity of MSCT for detecting significant stenosis were 91% and 97%, respectively. CONCLUSION: Our results indicate that 64-slice computed coronary angiography is a reliable diagnostic modality for the detection of significant coronary artery stenosis in patients with sinus rhythm and scheduled to have CCA, but still has limitations of diagnostic performance on a per-segment and per-vessel basis.

Safety and efficacy of patient preparation with intravenous esmolol before 64-slice computed tomography coronary angiography.

OBJECTIVE: To evaluate the safety and efficacy of heart rate reduction by intravenous esmolol in patients who are assigned for coronary angiography with 64-slice computed tomography (CT). METHODS: Five hundred consecutive patients were prospectively analyzed. Patients with an initial heart rate less than 65 beats per minute (bpm) did not receive esmolol. Patients with a heart rate between 65 and 80 bpm received a bolus dose of 1 mg/kg intravenous esmolol. Patients with an initial heart rate between 80 and 90 bpm received a bolus dose of 2 mg/kg intravenous esmolol. An additional 1 mg/kg intravenous esmolol was given to the patients when the target heart rate was not reached with the first bolus dose. Patients with an initial heart rate more than 90 bpm received 50 mg atenolol PO, and were reevaluated after 1 h. RESULTS: A total of 391 patients with a heart rate > or =65 bpm before multislice computed tomography (MSCT) examination received intravenous esmolol with a mean dose of 158+/-55 mg. Initial and final mean heart rates were 80+/-11 bpm and 63+/-7 bpm, respectively (P<0.0001). Heart rate below 65 bpm was reached in 265 (65%) of these 391 patients. Only four patients (1%) had a final heart rate above 80 bpm before MSCT imaging. Four of the 391 patients (1%) had a final heart rate below 50 bpm. CONCLUSION: Intravenous esmolol is safe and effective to reach the optimum heart rate in patients assigned for MSCT.

Prevalence of coronary artery disease in low to moderate-risk asymptomatic women: a multislice computed tomography study.

OBJECTIVES: Traditional risk factors may underestimate the burden of subclinical atherosclerosis in women. Recently, multislice computed tomography (MSCT) has become widely available in detecting early coronary artery disease (CAD). We sought the prevalence of CAD in low to moderate-risk asymptomatic women by MSCT coronary artery calcium (CAC) scoring and coronary angiography. STUDY DESIGN: The study included 185 women (mean age 57+/-12 years) without known CAD and diabetes, with low or moderate risk for CAD based on traditional risk scoring. Coronary artery calcium scoring and coronary angiography were performed by MSCT, which included a segment-based plaque detection and characterization of calcification. The plaques were classified based on the luminal stenotic effect (>50%). Patients with = or >1 stenotic plaque were classified as having obstructive CAD. Angiographic findings were compared with calcium scores. RESULTS: Coronary artery calcium scoring and coronary angiography detected CAD in 63 (34.1%) and 100 (54.1%) women, respectively. In both groups, women were significantly older and had higher prevalences of hypertension and dyslipidemia. Coronary angiography showed CAD in 41 women (41%; 14.6% were obstructive) without CAC. These women were significantly younger than those with a positive CAC score (p<0.01). Age (p<0.02) and hypertension (p<0.05) were found as independent predictors of CAD detected by coronary angiography. CONCLUSION: Multislice computed tomography identified a subset of low-risk women who might be at higher risk than that suggested by current risk stratification strategies. Women, especially having hypertension and dyslipidemia may be potential candidates for further risk stratification by MSCT coronary angiography.