Relation between combining evidence-based medications on mortality following myocardial infarction in patients with and without renal impairment.

BACKGROUND: Antiplatelet agents, beta-blockers, statins and ACE inhibitors have been shown to reduce mortality in patients following myocardial infarction (MI). However, it is uncertain if the combination of these agents has a similar impact on mortality following MI in patients with renal dysfunction. METHODS: We studied 5529 consecutive patients with confirmed MI between January 2000 and December 2003. Data on baseline demographics, co-morbidities and in-hospital management were collected prospectively. Glomerular filtration rate (GFR) was estimated using the 4-component Modification of Diet in Renal Disease equation. Based on discharge use of evidence-based medications, the patients were divided into those using 0, 1, 2, 3 or 4 medications. The impact of medication use on 1-year mortality was then assessed for patients with GFR > or =60 ml/min/1.73 m2 (group I) and GFR < 60 ml/min/1.73 m2 (group 2). RESULTS: Mean age was 63 +/- 13 years with 71% men.The prevalence of reduced GFR was 35% and the adjusted odds ratio for I-year mortality of patients in group 2 compared to those in group I was 1.86 (95% CI 1.54-2.25, P < 0.001). Compared with patients with no medication, the adjusted odds ratio for 1-year mortality was lower in patients with 1, 2, 3 and 4 medications in both groups. There was no significant interaction between the number of medications used and GFR. CONCLUSION: Increased use of combined evidence-based medications was independently associated with a lower 1-year post MI mortality. Such therapies offer similar survival benefit in patients with and without renal dysfunction.

Systematic assessment of procedural parameters, influence on downstream testing and 12-month outcomes of a CT-myocardial perfusion service.

AIMS: This study describes the real-world referral pattern of patients to a CT myocardial perfusion service, the technical issues associated with providing the service, the results of the studies, and the subsequent downstream utilization of other investigations, and patient outcomes. METHODS AND RESULTS: 115 consecutive patients underwent CTA, dynamic rest and dipyridamole-stress perfusion scanning. There were 29 (25%) and 14 (12%) patients who had reversible defects and fixed defects respectively, indicating abnormal flow reserve and previous infarction respectively. In the patients with fixed defects, delayed hyperenhancement was noted in all, indicative of prior infarction, scarring and non-viability. With the existing CTA Appropriateness Criteria, the categorization of "Appropriate," "Of Uncertain Appropriateness", and "Inappropriate" would have been applied to 25%, 25% and 50% of the present studies respectively. Up to 72% could have been referred for ischemia evaluation with other modalities of functional imaging after the non-diagnostic CT angiogram. Follow up was complete in 113 subjects (98%) over a period of 14 ±â€¯8 months. In the 29 patients with abnormal flow reserve and CAD, 62% underwent invasive angiography and 94%, angioplasty within a 90-day period. In the patients who underwent angioplasty, all remained free of myocardial infarction or death and 88% remained free of myocardial infarction, death or readmission over a mean of 14 ±â€¯8 months. CONCLUSION: A CT-myocardial perfusion service provided measures of ischemia and infarct detection over that of CTA alone. The information was utilized clinically by doctors to support a strategy of referral to revascularization versus conservative medical management.

The A-SACT (Achievement in Singapore of Cholesterol Targets) study in patients with coronary heart disease.

BACKGROUND: Cardiovascular disease remains a leading cause of death worldwide, with hypercholesterolemia being a major risk factor. Evidence-based consensus guidelines have recommended consideration of increasingly stringent cholesterol-lowering goals, yet most patients do not meet these targets. Coronary heart disease (CHD) event and mortality rates and mean serum cholesterol levels have declined in Singapore in recent years; however, certain groups remain at elevated risk. OBJECTIVE: To determine (i) proportions of patients with CHD in Singapore who achieved goals for serum low-density lipoprotein-cholesterol (LDL-C); and (ii) factors influencing goal attainment. METHODS: A historical cohort study was conducted using records from the Singapore Cardiac Databank, a national registry of CHD patients. Serum LDL-C goal attainment was assessed in 5174 survivors of acute myocardial infarction or coronary revascularization (i.e. coronary artery bypass graft surgery or percutaneous coronary interventions), of whom 3811 (73.7%) were at very high risk. RESULTS: At baseline, the mean patient age was 60.3 years, mean serum value of total cholesterol was 228 mg/dL, and mean LDL-C was 163 mg/dL. Of all CHD patients, approximately 70% did not achieve a serum LDL-C target of <100 mg/dL. Most patients receiving HMG-CoA reductase inhibitor (statin) regimens were treated initially with low- to medium-equipotency regimens and were never titrated to stronger regimens. The vast majority (approximately 94%) of patients at very high risk did not achieve the stringent serum LDL-C target of <70 mg/dL. Patients receiving higher potency statins were significantly more likely to achieve LDL-C goals, whereas those with higher baseline LDL-C levels or Malaysian ethnicity were less likely to achieve LDL-C goals. CONCLUSIONS: Most CHD patients in the large group of Singapore residents with CHD in the present study did not achieve recommended LDL-C targets. A more effective disease-management approach, including patient education concerning lifestyle modification (e.g. diet, physical activity), efforts to enhance medication adherence, and more effective, well tolerated therapies such as high-equipotency or high-dose statins and statin combination regimens, may be needed to improve achievement of consensus cholesterol targets. This is the first study of cholesterol goal attainment in a large group of Southeast Asians and serves as a baseline for future evaluations in Asian populations.

Instant dissolution of intracoronary thrombus by abciximab.

Formation of intracoronary thrombus during percutaneous coronary intervention can lead to acute vessel closure and myocardial infarction if prompt action is not taken. Thrombus removal using mechanical thrombectomy is the common treatment approach. We report a rare case of thrombus formation immediately after guidewire advancement, causing acute myocardial ischemia. Intracoronary bolus of abciximab was given and this resulted in prompt dissolution of the thrombus. The procedure proceeded uneventfully and there was no myocardial damage. This is consistent with a recent report suggesting that intracoronary abciximab may be more beneficial than standard intravenous administration for patients undergoing emergency coronary intervention for acute coronary syndrome.

Transplantation of autologous bone marrow-derived cells into the myocardium of patients undergoing coronary bypass.

BACKGROUND: Animal studies suggest that cell transplantation, including bone marrow-derived cells, can ameliorate left ventricular remodeling following myocardial ischemia. Clinical evaluation of the potential benefits of this approach is limited by the lack of safety and feasibility studies. We have assessed the safety and feasibility of intramyocardial transplantation of autologous bone marrow-derived cells in patients undergoing coronary artery bypass graft (CABG) surgery. METHODS AND RESULTS: Between December 2001 and May 2002 7 patients, scheduled for CABG, consented to the trial. All had CABG using hypothermic cardiopulmonary bypass (CPB) and cold cardioplegic arrest. An average of 21 10(6) (8.6 10(6) to 35.1 10(6)) nucleated cells, and 4.2 10(4) (2.5 10(4) to 8.1 10(4)) CD34+ cells were injected into the anterior-lateral wall of the left ventricle, after discontinuation of cardiopulmonary bypass. The end points to assess safety included death, massive bleeding, electrocardiographic or biochemical evidence of myocardial infarction, ventricular dysrhythmia, myocardial perfusion, ventricular function, and the patients' functional status. All patients recovered well without ventricular arrhythmia, bleeding, or other major peri-operative complications. The average intensive care unit (ICU) and hospital stay was 1 and 7 days, respectively. Repeat Technetium-99m myocardial perfusion stress imaging and echocardiography 6 weeks after surgery showed improvement in tissue perfusion, and an average improvement of left ventricular function of 13.5% +/- 11.54% (the mean pre- and post-operative left ventricular EF were 32.5% +/- 15.46% and 46% +/- 18.55%, respectively). Twenty-four hours Holter monitoring showed no significant arrhythmia, 3 months post-operatively. All patients with narrow QRS complex showed no evidence of late potential, on signal-averaged electrocardiogram. At 4 to 9 months after surgery patients were in NYHA functional class "I". CONCLUSIONS: This early clinical experience shows that autologous bone marrow-derived cell transplantation into myocardium is feasible and relatively safe. Further clinical trials to assess the role of cell transplantation for myocardial repair are required.

Dynamic CT myocardial perfusion measurements of resting and hyperaemic blood flow in low-risk subjects with 128-slice dual-source CT.

AIMS: The aim of the study was to measure rest and stress myocardial blood flow (MBF) values prospectively in a low-risk population with 128-slice dual-source computed tomography (CT) and to compare MBF/coronary flow reserve (CFR) values to that of a second population with a documented coronary artery disease (CAD). METHODS AND RESULTS: This study evaluates resting and hyperaemic MBF in 35 low-risk individuals identified by the modified Framingham Risk score and a calcium score of <100. The patients were scanned using 80 kV and quantitative blood flow values were generated using complete time-attenuation curves. Global resting and hyperaemic MBF was 74.08 ± 16.30 and 135.24 ± 28.89 mL/100 g/min, respectively, with CFR of 1.86 ± 0.38. Resting MBF was 76.98 ± 25.68, 66.98 ± 19.66, 81.34 ± 21.40, and 63.35 ± 16.35 mL/100 g/min in anterior, septal, lateral, and inferior walls, respectively, and corresponding hyperaemic MBF was 133.25 ± 29.80, 123.47 ± 31.03, 148.60 ± 32.69, and 124.21 ± 31.54 mL/100 g/min, respectively. In the population with CAD, global resting and hyperaemic MBF were 82.29 ± 16.87 and 81.98 ± 18.54 mL/100 g/min and 107.95 ± 25.25 and 106.93 ± 32.91 mL/100 g/min in the group with ischaemia only and infarction only, respectively, with corresponding CFR of 1.33 ± 0.27 and 1.33 ± 0.46, respectively (statistically different from the low-risk population). Radiation dose for CT myocardial perfusion imaging (CTMPI) was 6.72 ± 2.71 and 6.19 ± 2.19 mSv for stress and rest scans, respectively. This was 30% lower than a radiation dose in the scanning historical cohort at 100 kV. There was no significant difference in the signal-to-noise ratio and contrast-to-noise ratio between low-risk cohort and historical cohort scanned at 80 and 100 kV, respectively. CONCLUSIONS: Baseline, hyperaemic MBF and CFR values in a low-risk cohort can be evaluated with dynamic myocardial perfusion imaging using 80 kV.

Use of a simple clinical score to predict prognosis of patients with normal or mildly abnormal resting electrocardiographic findings undergoing evaluation for coronary artery disease.

OBJECTIVE: To determine whether a simple clinical score, which was shown previously to predict the likelihood of severe coronary artery disease (CAD) in patients referred for coronary angiography, could predict prognosis in a separate cohort of patients with normal or mildly abnormal findings on their resting electrocardiogram (ECG) who were undergoing noninvasive evaluation for possible CAD. PATIENTS AND METHODS: The study group included 2255 symptomatic patients with normal (n=1466) or mildly abnormal (nonspecific ST-T-wave abnormalities; n=789) findings on their resting ECG who were referred for exercise thallium testing between 1989 and 1991. Follow-up was 94% complete at a mean +/- SD duration of 6.9+/-1.5 years. The clinical score, which ranged from 0 (lowest risk) to 10 (highest risk), was calculated by awarding 1 point each for male sex, history of myocardial infarction, typical angina, diabetes mellitus, insulin use, and each decade of age older than 40 years. RESULTS: In each ECG group, the clinical score was a significant predictor of cardiac death, nonfatal myocardial infarction, or late revascularization, considered individually or combined, unadjusted or with adjustment for age. Most patients had a score lower than 5; these patients had an excellent 5-year cardiac survival rate (99.7% for the normal ECG findings group and 98.8% for the ST-T-wave abnormalities group). The small subset of patients with a score higher than 5 had a much lower 5-year survival rate (923% for the 8% of patients with normal ECG findings and 86.6% for the 14% of patients with ST-T-wave abnormalities). For patients with a score of 5, the 5-year survival rate was 97.7% for the normal ECG findings group and 95.9% for the ST-T-wave abnormalities group. CONCLUSION: In symptomatic patients with known or suspected CAD and normal or mildly abnormal resting ECG findings, this simple, easily computed clinical score is a useful and valid tool to help determine prognosis.

CT myocardial perfusion imaging of myocardial blood flow reserve before and after coronary artery stenting.

A patient with crescendo angina underwent CTA, CTMPI and invasive angiography. Abnormal flow reserve was demonstrated in the RCA territory, which corresponded to a significant lesion demonstrated on CTA and invasive angiography. The defect was demonstrated prior to PCI, and resolved post PCI.

Stress and rest dynamic myocardial perfusion imaging by evaluation of complete time-attenuation curves with dual-source CT.

OBJECTIVES: This study sought to describe a protocol for myocardial perfusion imaging using dipyridamole stress, with 128-slice dual-source computed tomography (CT), and to assess the ability of CT myocardial perfusion imaging (MPI) to detect abnormal flow reserve and infarction in comparison with nuclear MPI (NMPI). BACKGROUND: CT MPI has not been previously described with the 128-slice dual-source CT scanner, or with the complete evaluation of dynamic time-attenuation curves of the myocardium. METHODS: Thirty-five patients underwent a stress CT MPI protocol. Complete time-attenuation curves of the myocardium were acquired using a novel scan mode, which acquires prospectively electrocardiogram (ECG)-triggered axial images at 2 rapidly alternating positions. Myocardial blood flow (MBF) values of fixed and reversible defects obtained were compared between rest and stress. Findings on CT MPI were correlated to NMPI. Perfusion defects detected on CT were correlated to coronary stenoses detected on CT angiography (CTA) and invasive coronary angiography (ICA). RESULTS: There was a 1.5-fold difference between stress (1.21 +/- 0.31 cc/cc/min) and rest (0.82 +/- 0.22 cc/cc/min) MBF in normal tissue. In reversible defects, MBF was 0.65 +/- 0.21 cc/cc/min and 0.63 +/- 0.18 cc/cc/min at stress and rest, respectively. In fixed defects, the MBF was 0.57 +/- 0.22 cc/cc/min at stress and 0.54 +/- 0.23 cc/cc/min at rest. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT MPI for identifying segments with perfusion defects was 0.83, 0.78, 0.79, and 0.82, respectively. ICA results were available for 30 patients. Sensitivity, specificity, PPV, and NPV of CT MPI compared with ICA were 0.95, 0.65, 0.78, and 0.79, respectively. The radiation dose for CT MPI was 9.15 +/- 1.32 mSv for the stress scan and 9.09 +/- 1.40 mSv for the rest scan. CONCLUSIONS: Vasodilator-stress CT MPI may be feasible in human subjects at a radiation dose similar to NMPI. It identifies areas of abnormal flow reserve and infarction with a high degree of correlation to NMPI as well as to stenoses detected in CTA and ICA.

Comprehensive noninvasive evaluation of bypass grafts and native coronary arteries in patients after coronary bypass surgery: accuracy of 64-slice multidetector computed tomography compared to invasive coronary angiography.

AIMS: We assessed the accuracy of 64-slice multidetector computed tomography (MDCT) compared with that of invasive coronary angiography (ICA) in the evaluation of symptomatic postcoronary artery bypass graft (post-CABG) patients. METHODS: MDCT and ICA were performed in 44 consecutive post-CABG patients with chest pain (mean age 66 +/- 10 years, mean duration post-CABG 9 +/- 5 years). MDCT findings were compared with the corresponding ICA, which was read by an interventional cardiologist blinded to the MDCT findings. Significant stenosis was defined as at least 50% luminal stenosis. RESULTS: One hundred and thirty-seven grafts (31 arterial and 106 venous), all evaluable by MDCT, were assessed. In a 'per graft' analysis, MDCT could detect significant disease in bypass grafts (graft occlusion or stenosis) with a sensitivity of 98% and specificity of 98%. In a 'per segment' analysis, MDCT could detect significant disease in all native coronary arteries with a sensitivity of 91% and specificity of 79% and in clinically relevant native coronary arteries with a sensitivity of 92% and specificity of 84%. In a 'per vessel' analysis, MDCT could differentiate native arterial occlusion from nonocclusive stenosis with a sensitivity of 68% and specificity of 70%. In a 'per patient' analysis, MDCT could detect significant disease in bypass grafts or clinically relevant native coronary arteries with a sensitivity of 100%, specificity of 40% and accuracy of 93%. CONCLUSION: Sixty-four-slice MDCT allows evaluation of bypass grafts and native coronary arteries in post-CABG patients. Although accurate for detecting bypass graft disease, 64-slice MDCT has significant limitations when evaluating native arteries in post-CABG patients.

Impact of diabetes mellitus on survival in South East Asian patients with congestive heart failure due to left ventricular systolic dysfunction.

OBJECTIVE: We assessed the impact of diabetes mellitus on survival in South East Asian patients with congestive heart failure. METHODS: 1668 consecutive patients with chronic heart failure (age 65+/-13 years, ejection fraction 28+/-12%, 67% male) were followed up for 36+/-12 months. 837 patients (50.2%) were diabetic and 1076 patients (65%) had ischemic cardiomyopathy. Primary outcome measure was all-cause mortality. Secondary outcome measures were heart failure readmission and the composite end-point. RESULTS: There were 223 (13.4%) deaths and 112 (7%) heart failure readmissions. Ischemic cardiomyopathy, renal failure, hypertension, cerebrovascular disease, peripheral vascular disease, and hyperlipidemia were more prevalent in diabetics (all p<0.01). All-cause mortality (17.3% vs 9.4%), heart failure readmission (8.1% vs 5.3%) and the composite end-point (21.9% vs 12.6%) occurred more frequently in diabetics (all p<0.05). Diabetes was an independent predictor of all-cause mortality (OR=1.70, p=0.01), as were ischemic cardiomyopathy (OR=1.85, p=0.01), hypertension (OR=1.78, p=0.01), GFR (OR=0.98, p<0.01), and beta-blocker use (OR=0.55, p<0.01). CONCLUSIONS: In spite of advances in heart failure treatment, the presence of diabetes mellitus significantly worsens survival in South East Asian patients with congestive heart failure.

Prevalence of non-cardiac findings in a large series of patients undergoing cardiac multi-detector computed tomography scans.

The purpose of our study was to determine the prevalence of non-cardiac findings in a large series of patients undergoing contrast-enhanced cardiac multi-detector computed tomography (MDCT) scans. Non-cardiac findings were classified according to the organ of involvement and level of significance. We retrospectively reviewed scans and reports of 1,061 patients performed between 1 April 2004 and 31 April 2006. Non-cardiac findings were considered significant if they warranted further radiological or clinical follow-up. A total of 103 non-cardiac findings were reported in 85 (8.0%) of the 1,061 patients. Of these lesions, 48 (46.7%) were significant and 55 (53.3%) were not. The significant lesions were found in 33 of the 1,061 patients (3.1%). Among the significant abnormalities, the three most common were pulmonary nodules (16.7%), emphysema (16.7%) and possible hepatic carcinomas (12.6%). Patients with non-cardiac findings were significantly older than those without (mean age 60 +/- 6 years vs. 55 +/- 8 years; P < 0.0001). The prevalence of active smoking was significantly higher in patients with non-cardiac findings (28.2 vs. 17.8%; P = 0.03). The prevalence of non-cardiac abnormalities detected by cardiac MDCT was 8% and about half of these findings were deemed significant. These lesions commonly occurred in the lungs and the liver. Age and active smoking were predictive of the presence of non-cardiac abnormalities.

Exercise myocardial perfusion stress testing in children with Kawasaki disease.

AIM: Kawasaki disease is the commonest cause of acquired coronary artery disease in children. Although echocardiography and treadmill stress testing have been the traditional methods of assessing coronary artery abnormalities and detecting myocardial ischaemia, respectively, these are inadequate for assessing perfusion and performance. We studied the safety and utility of exercise myocardial perfusion stress testing in children with previous Kawasaki disease. METHODS: Eleven subjects (median age 12 years; seven male and four female adolescents) with a history of childhood Kawasaki disease underwent 99mTechnetium-Tetrofosmin myocardial perfusion scan using a modified protocol. All had New York Heart Association effort tolerance class 1 and were asymptomatic at time of testing. Eight of 11 subjects had been treated with intravenous immunoglobulin during the acute phase. Six of 11 subjects had transient coronary artery dilatation. One subject with persistently dilated coronary arteries suffered an acute myocardial infarction 6 months after onset of Kawasaki disease but recovered well. Results were compared with clinical and echocardiographic findings. RESULTS: All subjects were able to complete the exercise test. There were no side effects associated with radioisotope injection. Ten of 11 patients, including the one who suffered a myocardial infarction had normal tests. The single subject with an abnormal scan showed a minimal (2%) fixed defect in the left ventricular wall. CONCLUSION: Exercise myocardial perfusion stress is a safe and useful method for the assessment of myocardial perfusion in co-operative children with a history of Kawasaki disease and is a useful addition to conventional methods for coronary risk stratification in such patients.

Six-minute walk distance in healthy Singaporean adults cannot be predicted using reference equations derived from Caucasian populations.

OBJECTIVES: The 6-min walk test (6MWT) is commonly used to assess the functional exercise capacity of individuals with cardiopulmonary disease. Recent studies have established regression equations to predict the 6-min walk distance (6MWD) in healthy Caucasian populations; however, regression equations have yet to be established for the Singaporean population. The aim of this study was to determine 6MWD in healthy Singaporeans and identify contributors to 6MWD in this population. We also compared measured 6MWD with predicted 6MWD from two regression equations derived in Caucasian subjects. METHODOLOGY: Thirty-five healthy subjects (32 Chinese, 16 men) aged between 45 and 85 years performed three walking tests using a standardized protocol. 6MWD was defined as the greatest distance achieved from the three tests. Heart rate (HR) was recorded each minute during the 6MWT. Other measurements included age, height, leg length, smoking history and self-reported physical activity. RESULTS: 6MWD was 560 +/- 105 m and was not significantly different between men and women (P = 0.19). 6MWD was related to age (r = -0.36, P = 0.03), height (r = 0.35, P = 0.04), leg length (r = 0.38, P = 0.02) and the maximum HR achieved on the 6MWT when expressed as a percentage of the predicted maximum HR (%predHRmax, r = 0.73, P < 0.001). Stepwise multiple regression analysis showed that age, height, weight and %predHRmax were independent contributors (P < 0.01) to 6MWD, explaining 78% of the variance. Predicted 6MWD using regression equations derived from Caucasian subjects exceeded measured 6MWD by more than 75 m (P < 0.001). CONCLUSIONS: This is the first study to report 6MWD for healthy Singaporeans aged 45-85 years. The regression equation developed in this study explained 78% of the variance in 6MWD. Published equations derived from Caucasian subjects overestimate 6MWD in Singaporean Chinese.