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Michael S Chen

Publications and source records attributed to Michael S Chen.

14 recordsLinked to original sources
PubMed2006

Paradoxical increase in lumen size during progression of coronary atherosclerosis: observations from the REVERSAL trial.

Relative changes in lumen size during progression and regression of coronary atherosclerosis remain largely unknown. We assessed these changes using serial intravascular ultrasound (IVUS). From the baseline IVUS interrogations of the Reversal of Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) trial, 210 focal coronary lesions with <50% angiographic stenosis were identified. Lesions were matched to the follow-up IVUS, performed after 18 months of treatment with atorvastatin 80 mg/day or pravastatin 40 mg/day. Changes in external elastic membrane (EEM) and lumen areas of lesions demonstrating progression and regression (i.e. increased and decreased atheroma area) were examined. In progressors (n=128), there was 1.34 mm(2) increase in EEM area for every 1mm(2) increase in atheroma area (r=0.72, p<0.0001). This resulted in 0.34 mm(2) increase in lumen area for every 1mm(2) increase in atheroma area (r=0.25, p=0.004). In contrast, there was no significant change in lumen area with regression of disease (n=82, r=-0.06, p=0.59). Progression of coronary atherosclerosis can be associated with a paradoxical increase in lumen cross-sectional area, whereas regression is not associated with any change in lumen area. Measurement of changes in lumen size may not be an accurate method to study progression and regression of atherosclerotic lesions with <50% stenosis.

Adult↗
PubMed2006

Bare metal stent restenosis is not a benign clinical entity.

BACKGROUND: Restenosis after percutaneous coronary intervention (PCI) has been thought to present in a stable manner as exertional angina. However, the presentation of in-stent restenosis (ISR) is not well-studied. We hypothesized that a substantial proportion of bare metal ISR presents as acute coronary syndromes. We aimed to characterize the severity of the clinical presentation of ISR. METHODS: We searched our PCI database for all cases of PCI for bare metal ISR occurring between May 1999 and September 2003. Multivessel interventions were excluded. In-stent restenosis presentation was classified into three categories: (1) myocardial infarction (MI), (2) unstable angina requiring hospitalization before angiography, and (3) exertional angina. Routine angiographic screening after initial stent placement was not performed, so ISR episodes were clinical, rather than angiographic, ISR. RESULTS: We identified 1186 cases of bare metal ISR in 984 patients. Median age was 63, 72% were male, and 36% had diabetes. Of the ISR episodes, 9.5% presented as acute MI (7.3% as non-ST-segment elevation MI and 2.2% as ST-segment elevation MI), 26.4% as unstable angina requiring hospitalization before angiography, and 64.1% as exertional angina. CONCLUSIONS: More than one third of bare metal ISR episodes presented as MI or unstable angina requiring hospitalization. The acuity of the clinical presentation of bare metal ISR appears to be more severe than has been previously thought. Aggressive efforts, such as drug-eluting stents to decrease the incidence of unstable angina due to bare metal ISR, are warranted.

Acute Disease↗
PubMed2005

Direct thrombin inhibitors.

Direct thrombin inhibitors (DTIs) are a new class of therapeutics possessing theoretic advantages over unfractionated heparin (UFH). In contrast to UFH, DTIs do not activate platelets, have no circulating inhibitors, and bind to both free and clot-bound thrombin. These theoretical advantages have spurred clinical trials investigating DTIs in a variety of cardiovascular indications. Currently, the major role for DTIs in cardiology is as an adjunct during percutaneous coronary intervention (PCI). Such a role stems from the results of the Randomized Evaluation in PCI Linking Angiomax to Reduced Clinical Events (REPLACE)-2 randomized trial, in which bivalirudin with provisional abciximab was demonstrated to be equivalent to UFH plus planned abciximab with respect to ischemic endpoints, while being associated with less bleeding. Ongoing clinical trials will define the role of bivalirudin as an adjunct to primary PCI for ST-segment elevation myocardial infarction and in non-ST segment elevation acute coronary syndrome as an adjunct to an early invasive strategy.

Abciximab↗
PubMed2005

Outcomes in African Americans and whites after percutaneous coronary intervention.

PURPOSE: We aimed to determine whether African Americans and whites have different outcomes after percutaneous coronary intervention (PCI). METHODS: We prospectively selected 8832 patients (707 African Americans) for long-term follow-up after PCI at our institution from 1992 to 2002. The primary outcome studied was death or myocardial infarction at 1 year. Propensity adjustment was performed to account for baseline differences between African Americans and whites. RESULTS: African Americans had higher rates of diabetes and less prior revascularization. Percutaneous coronary interventions in African Americans were more often urgent. Stent use was similar. Procedural success rates were similar, as were periprocedural and 30-day composite rates of death or myocardial infarction. In 1-year unadjusted outcomes, African Americans had a higher rate of death or myocardial infarction (18.0% vs 14.5%; hazard ratio (HR) = 1.25; 95% confidence interval (CI): 1.04 to 1.50; P = 0.017), but the difference was no longer significant after propensity adjustment (HR = 1.18; 95% CI: 0.98 to 1.43, P = 0.087). African Americans had a higher risk for periprocedural bleeding that persisted after propensity adjustment (adjusted odds ratio = 1.45; 95% CI: 1.14 to 1.84, P = 0.002). CONCLUSIONS: After PCI, African Americans have similar short-term rates of death or myocardial infarction when compared with whites but have a nonsignificant trend toward worse long-term outcomes. Our findings, when interpreted in the context of reportedly lower revascularization rates among African Americans, suggest that continued efforts to optimize the appropriate use of coronary revascularization among African Americans are warranted.

Black or African American↗
PubMed2005

A right atrial mass and a pseudomass.

Right atrial (RA) masses are rare entities often detected incidentally during imaging studies. Leading etiologies of right atrial masses are tumor, thrombi, and vegetations. We present two cases of right atrial masses, a cardiac lipoma and an artifact. Clinical and echocardiographic characteristics of benign cardiac tumors are reviewed. We then highlight the importance of considering artifact in the differential diagnosis of atrial masses. Finally, we discuss echocardiographic characteristics of right atrial masses that may provide clues for diagnosis. Right atrial masses, often detected incidentally during imaging studies, are uncommon and can be due to many etiologies including tumors, thrombus, vegetations, normal variants, and artifacts. We describe 2 patients with RA masses detected on routine transthoracic echocardiogram.

Aged↗
PubMed2004

Heart rate recovery and impact of myocardial revascularization on long-term mortality.

BACKGROUND: Although heart rate recovery (HRR) predicts mortality after exercise testing, its ability to identify patients likely to benefit after revascularization is unknown. We sought to determine whether HRR can identify patients likely to have improved survival after revascularization. METHODS AND RESULTS: A total of 8861 patients undergoing treadmill nuclear or echocardiographic testing were divided into early revascularization (percutaneous coronary intervention or bypass surgery within 3 months) and non-early revascularization groups. Prespecified subgroup analysis was performed based on the presence or absence of ischemia, normal or impaired functional capacity, and normal or abnormal HRR. The primary end point was all-cause mortality. Early revascularization occurred in 552 patients. We propensity-matched 508 early revascularization patients to 508 non-early revascularization patients on the basis of 48 possible confounders. This constituted the present study cohort. During 8-year follow-up, 232 patients died. Overall, revascularization was associated with a slight but not significant decrease in mortality (hazard ratio [HR] 0.80, 95% CI 0.62 to 1.03). A significant decrease in mortality after revascularization was present in patients with imaging evidence of stress-induced ischemia (HR 0.62, 95% CI 0.44 to 0.87). Ischemic patients with normal HRR had significantly lower mortality with revascularization (HR 0.55, 95% CI 0.34 to 0.90), whereas ischemic patients with abnormal HRR did not (HR 0.78, 95% CI 0.47 to 1.29); however, the test for interaction between these 2 groups was not significant (P=0.34). CONCLUSIONS: In patients with imaging evidence of myocardial ischemia, an abnormal HRR is associated with a nonsignificant trend toward blunting the survival improvement associated with early revascularization. HRR does not appear to identify patients likely to have a survival benefit.

Aged↗
PubMed2004

Pulmonary vein isolation for the treatment of atrial fibrillation in patients with impaired systolic function.

OBJECTIVES: We aimed to determine the safety and efficacy of pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients with impaired left ventricular (LV) systolic function. BACKGROUND: To date, PVI has been performed primarily in patients with normal LV function. Yet, many AF patients have impaired LV systolic function. The outcomes of PVI in patients with impaired LV systolic function are unknown. METHODS: We included 377 consecutive patients undergoing PVI between December 2000 and January 2003. Ninety-four patients had impaired LV function (ejection fraction [EF] <40%), and they comprised the study group. The control group was the remaining 283 patients who had a normal EF. End points included AF recurrence and changes in EF and quality of life (QoL). RESULTS: Mean EF was 36% in our study group, compared with 54% in controls. After initial PVI, 73% of patients with impaired EF and 87% of patients with normal EF were free of AF recurrence at 14 +/- 6 months (p = 0.03). In the study group, there was a nonsignificant increase in EF of 4.6% and significant improvement in QoL. Complication rates were low and included a 1% risk of pulmonary vein stenosis. CONCLUSIONS: Although the AF recurrence rate after initial PVI in impaired EF patients was higher than in normal EF subjects, nearly three-fourths of patients with impaired EF remained AF-free. Although our sample size was nonrandomized, our results suggest PVI may be a feasible therapeutic option in AF patients with impaired EF. Randomized studies with more patients and longer follow-up are warranted.

Atrial Fibrillation↗
PubMed2004

Feasibility of simultaneous bilateral carotid artery stenting.

Due to the progressive aging of the population, severe bilateral carotid stenosis has become a more frequent condition. On occasion, simultaneous revascularization may be appropriate. There is increased evidence that for these high-risk patients, a percutaneous revascularization may be the best approach. However, there are concerns that simultaneous bilateral carotid stenting may be associated with cerebral hyperperfusion, excessive bradycardia, and hypotension. We report a series of 10 consecutive patients who underwent simultaneous bilateral carotid stenting. All of these patients were not deemed to be surgical candidates due to high-risk comorbidities. All but one of the lesions were successfully stented. There were no procedural deaths, myocardial infarctions, or strokes. Thus, among carefully selected patients, simultaneous bilateral carotid artery stenting is a promising, technically feasible option.

Adrenergic alpha-Agonists↗
PubMed2004

Pulmonary vein antrum isolation for treatment of atrial fibrillation in patients with valvular heart disease or prior open heart surgery.

OBJECTIVES: The goal of this study was to assess the safety and efficacy of pulmonary vein antrum isolation in patients with moderate valvular heart disease or open-heart surgery and atrial fibrillation (AF). BACKGROUND: Valvular heart disease and open-heart surgery are commonly associated with AF and increase the risk of adverse events in AF patients. METHODS: A total of 391 consecutive patients who had pulmonary vein antrum isolation performed between December 2000 and December 2002 were screened. A total of 142 of these patients had clinically significant valvular disease or prior cardiac surgery. End points included AF recurrence and pulmonary vein antrum isolation complication rates. RESULTS: Patients with valvular heart disease or prior open-heart surgery were older, had larger left atria and a more advanced New York Heart Association class. They did not differ significantly with respect to gender, but had a longer history of AF. Procedure times were similar between patients with and without valvular heart disease or prior open-heart surgery. After 18 +/- 7 months in the lone AF patients, 11 +/- 5 months in patients with valvular heart disease, and 10 +/- 5 months in patients with prior open heart surgery, there was a trend toward lower recurrence of AF in patients with lone AF who enjoyed a 98% overall cure rate after up to 2 pulmonary vein antrum isolations versus 93% among patients with valvular heart disease (P = .04) and prior open heart surgery (P = .07). Complication rates were comparable between groups. CONCLUSIONS: Pulmonary vein antrum isolation is safe and effective in patients with moderate valvular heart disease and the patients who developed AF after open-heart surgery. These results have implications for our understanding of the pathophysiology of AF in patients with moderate valvular heart disease or past cardiac surgery and should be considered when discussing treatment options in these patients.

Atrial Fibrillation↗
PubMed2003

Moricizine induced increase in pacing threshold.

A 72-year-old woman who was experiencing incessant ventricular tachycardia and recurrent automatic implantable cardioverter defibrillator (AICD) firing despite amiodarone therapy was referred to the Cleveland Clinic Foundation. Myocardial ischemia and infarction were ruled out by standard means. Several antiarrhythmic medications were tried previously without success. Moricizine, 200 mg three times daily, was initiated and controlled the ventricular tachycardia. However, after the dose of moricizine was titrated upward, the patient became symptomatically bradycardic and the ECG exhibited 2:1 block of her paced rhythm and an increased ventricular pacing threshold.

Aged↗
PubMed2002

The smoker's paradox: insights from the angiographic substudies of the TIMI trials.

BACKGROUND: Despite increased risk for coronary artery disease and acute myocardial infarction (AMI), smokers have a paradoxically lower mortality after thrombolysis for AMI than non-smokers. We determined the clinical risk profiles and coronary flow characteristics of patients in the TIMI trials according to smoking status, focusing on microvascular flow. METHODS: Among 2,573 patients in the TIMI 4, 10A, 10B and TIMI 14 trials, epicardial flow post-thrombolysis was measured using angiographic TIMI flow grades and the corrected TIMI frame count (CTFC). Microvascular flow was measured by TIMI Myocardial Perfusion Grade (TMPG) and, in TIMI 14, the percentage of ST segment resolution. RESULTS: Clinically, the mean age (54 vs. 62 years), the prevalence of diabetes mellitus (11% vs. 16%) and hypertension (26% vs. 40%), and the 30-day mortality (2.6% vs. 6.2%) were lower among smokers than non-smokers (all p < or = 0.001). Angiographically, single-vessel disease (48% vs. 40%) and non-left anterior descending infarct arteries (65.4% vs. 60.8%) were more common among smokers (both p < or = 0.01). Epicardial TIMI grade 3 flow was achieved more often in smokers than non-smokers (61% vs. 56%) and the CTFC was faster (34 vs. 37 frames/sec, both p < or = 0.01), especially in LAD lesions. However, the frequency of normal microvascular flow (TMPG 3) was similar among smokers and non-smokers (24% vs. 29%, p = 0.16), as was the frequency of complete ST segment resolution (50% vs. 46%, p = 0.29). CONCLUSIONS: Smokers have lower mortality after AMI than non-smokers, due in large part to lower clinical risk profiles and faster epicardial flow. Differences in tissue-level perfusion do not appear to contribute to lower mortality in smokers.

Adult↗
PubMedDate not supplied

Highlights of the 2002 update to the 2000 American College of Cardiology/American Heart Association acute coronary syndrome guidelines.

Since the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for acute coronary syndrome (ACS) were published in 2000, a wealth of clinical evidence has accumulated. To incorporate this recent clinical data, an update to the 2000 ACC/AHA guidelines was issued in 2002. The revised ACC/AHA guidelines emphasize risk stratification of ACS patients to help guide therapy. In antiplatelet therapy, clopidogrel has gained a more prominent role in the treatment of ACS, both in breadth of patients and duration of treatment. Ticlopidine is no longer recommended. More guidance is provided with respect to specific glycoprotein IIb/IIIa inhibitor use in subgroups of ACS patients. In anticoagulation therapy, enoxaparin is now favored over unfractionated heparin. Finally, class I indications for an early invasive strategy have been expanded to include patients with elevated cardiac markers or new ST segment depression. Early initiation and continuation of a hepatic hydroxymethyl glutaryl coenzyme A reductase inhibitor is recommended if low-density lipoprotein cholesterol is higher than 100 mg/dL, and the addition of niacin or a fibrate is recommended in patients with isolated low high-density lipoprotein cholesterol. This article summarizes the major modifications to the ACS guidelines and highlights the clinical evidence prompting such changes.

Acute Disease↗