Prognostic value of dobutamine stress technetium-99m-sestamibi single-photon emission computed tomography myocardial perfusion imaging: stratification of a high-risk population.

OBJECTIVES: This work was undertaken to define the intrinsic cardiac risk of the patient population referred for dobutamine stress perfusion imaging and to determine whether dobutamine technetium-99m ((99m)Tc)-sestamibi single-photon emission computed tomography (SPECT) imaging is capable of risk stratification in this population. BACKGROUND: In animal models, dobutamine attenuates the myocardial uptake of (99m)Tc-sestamibi resulting in underestimation of coronary stenoses. Therefore, we hypothesized that the prognostic value of dobutamine stress (99m)Tc-sestamibi SPECT myocardial perfusion imaging might be impaired, owing to reduced detection of coronary stenoses. METHODS: We reviewed the clinical outcome of 308 patients (166 women, 142 men) who underwent dobutamine stress SPECT (99m)Tc-sestamibi imaging at our institution from September 1992 through December 1996. RESULTS: During an average follow-up of 1.9 +/- 1.1 years, there were 33 hard cardiac events (18 myocardial infarctions [MI] and 15 cardiac deaths) corresponding to an annual cardiac event rate of 5.8%/year, which is significantly higher than the event rate for patients referred for exercise SPECT imaging at our institution (2.2%/year). Event rates were higher after an abnormal dobutamine (99m)Tc-sestamibi SPECT study (10.0%/year) than after a normal study (2.3%/year) (p < 0.01), even after adjusting for clinical variables. In the subgroup (n = 29) with dobutamine-induced ST-segment depression and abnormal SPECT imaging, the prognosis was poor, with annual cardiac death and nonfatal MI rates of 7.9% and 13.2%, respectively. CONCLUSIONS: Patients referred for dobutamine perfusion imaging are a high-risk population, and dobutamine stress (99m)Tc-sestamibi SPECT imaging is capable of risk stratification in these patients.

Survival of patients with diabetes and multivessel coronary artery disease after surgical or percutaneous coronary revascularization: results of a large regional prospective study. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to assess survival among patients with diabetes and multivessel coronary artery disease (MVD) after percutaneous coronary intervention (PCI) and after coronary artery bypass grafting surgery (CABG). BACKGROUND: The Bypass Angioplasty Revascularization Investigation (BARI) demonstrated that diabetics with MVD survive longer after initial CABG than after initial PCI. Other randomized trials or observational databases have not conclusively reproduced this result. METHODS: A large, regional database was linked to the National Death Index to assess five-year mortality. Of 7,159 consecutive patients with diabetes who underwent coronary revascularization in northern New England during 1992 to 1996, 2,766 (38.6%) were similar to those randomized in the BARI trial. Percutaneous coronary intervention was the initial revascularization strategy in 736 patients and CABG in 2,030. Cox proportional hazards regression was used to calculate risk-adjusted hazard ratios (HR) and 95% confidence intervals (CI 95%). RESULTS: Patients who underwent PCI were younger, had higher ejection fractions and less extensive coronary disease. After adjusting for differences in baseline clinical characteristics, patients with diabetes treated with PCI had significantly greater mortality relative to those undergoing CABG (HR = 1.49; CI 95%: 1.02 to 2.17; p = 0.037). Mortality risk tended to increase more among 1,251 patients with 3VD (HR = 2.02; CI 95%: 1.04 to 3.91; p = 0.038) than among 1,515 patients with 2VD (HR = 1.33; CI 95%: 0.84 to 2.1; p = 0.21). CONCLUSIONS: In this analysis of a large regional contemporary database of patients with diabetes selected to be similar to those enrolled in the BARI trial, five-year mortality was significantly increased after initial PCI. This supports the BARI conclusion on initial revascularization of patients with diabetes and MVD.

Safety and efficacy of percutaneous coronary interventions performed immediately after diagnostic catheterization in northern new england and comparison with similar procedures performed later.

"Ad hoc" percutaneous coronary interventions (PCIs)-those performed immediately after diagnostic catheterization-have been reported in earlier studies to be safe with a suggestion of higher risk in certain subgroups. Despite increasing use of this strategy, no data are available in recent years with new device technology. We studied use of an ad hoc strategy in a large regional population to determine its use and outcomes compared with staged procedures. A database from the 6 centers performing PCIs in northern New England and 1 center in Massachusetts was analyzed. During 1997, excluding only patients requiring emergency procedures or those with a prior PCI, 4,136 PCIs were performed, 1,748 (42.3%) of these being ad hoc procedures. Patients having ad hoc procedures were less likely to have peripheral vascular disease, renal failure, prior myocardial infarction, or coronary artery bypass surgery, congestive heart failure, or poor left ventricular function, and more likely to have received preprocedural intravenous heparin or nitroglycerin or to have required an urgent procedure. Narrowings treated during ad hoc procedures were less frequently types B and C or in saphenous vein grafts. Adjusted rates of clinical success were not different between ad hoc and non-ad hoc procedures (93.7% vs 93.6%); there was no difference in the incidence of death (0.6% vs 0.5%), emergency (0. 9% vs 0.8%) or any (1.4% vs 0.8%) coronary artery bypass surgery, or myocardial infarction (2.6% vs 2.0%). As currently practiced in our region, ad hoc intervention is used selectively with outcomes similar for ad hoc and non-ad hoc procedures.

Mediastinitis and long-term survival after coronary artery bypass graft surgery.

BACKGROUND: Mediastinitis is a dreaded complication of coronary artery bypass surgery (CABG). The long-term effect of mediastinitis on mortality after CABG has not been well studied. METHODS: We examined the survival of 15,406 consecutive patients undergoing isolated CABG surgery from 1992 through 1996. Patient records were linked to the National Death Index. Mediastinitis was defined as occurring during the index admission and requiring reoperation. RESULTS: Mediastinitis occurred in 193 patients (1.25%). Patients with mediastinitis were older and more likely to have had emergency surgery, diabetes, peripheral vascular disease, chronic obstructive pulmonary disease, and preoperative dialysis-dependent renal failure. Patients with mediastinitis were also more likely to be severely obese and had somewhat lower preoperative ejection fraction. After multivariate adjustment for these factors, the first year post-CABG survival rate was 78% with mediastinitis and 95% without, and the hazard ratio for mortality during the entire follow-up period was 3.09 (CI 95% 2.28, 4.19; p < 0.0001). CONCLUSIONS: Mediastinitis is associated with a marked increase in mortality during the first year post-CABG and a threefold increase during a 4-year follow-up period.

Relation between operator and hospital volume and outcomes following percutaneous coronary interventions in the era of the coronary stent.

CONTEXT: Studies have found an association between physician and institution procedure volume for percutaneous coronary interventions (PCIs) and patient outcomes, but whether implementation of coronary stents has allowed low-volume physicians and centers to achieve outcomes similar to their high-volume counterparts is unknown. OBJECTIVE: To assess the relationship between physician and hospital PCI volumes and patient outcomes following PCIs, given the availability of coronary stents. DESIGN, SETTING, AND PARTICIPANTS: Analysis of data from Medicare National Claims History files for 167 208 patients aged 65 to 99 years who had PCIs performed by 6534 physicians at 1003 hospitals during 1997. Of these procedures, 57.7% involved coronary stents. MAIN OUTCOME MEASURES: Rates of coronary artery bypass graft (CABG) surgery and 30-day mortality occurring during the index episode of care, stratified by physician and hospital PCI volume. RESULTS: Overall unadjusted rates of CABG during the index hospitalization and 30-day mortality were 1.87% and 3.30%, respectively. After adjustment for case mix, patients treated by low-volume (<30 Medicare procedures) physicians had an increased risk of CABG vs patients treated by high-volume (>60 Medicare procedures) physicians (2.25% vs 1.55%; P<.001), but there was no difference in 30-day mortality rates (3.25% vs 3.39%; P =.27). Patients treated at low-volume (<80 Medicare procedures) centers had an increased risk of 30-day mortality vs patients treated at high-volume (>160 Medicare procedures) centers (4.29% vs 3.15%; P<. 001), but there was no difference in the risk of CABG (1.83% vs 1. 83%; P =.96). In patients who received coronary stents, the CABG rate was 1.20% vs 2.78% for patients not receiving stents, and the 30-day mortality rate was 2.83% vs 3.94%. Among patients who received stents, those treated at low-volume centers had an increased risk of 30-day mortality vs those treated at high-volume centers, whereas those treated by low-volume physicians had an increased risk of CABG vs those treated by high-volume physicians. CONCLUSION: In the era of coronary stents, Medicare patients treated by high-volume physicians and at high-volume centers experience better outcomes following PCIs.

The relationship between operator volume and outcomes after percutaneous coronary interventions in high volume hospitals in 1994-1996: the northern New England experience. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: The purpose of this study was to examine the relationship between annual operator volume and outcomes of percutaneous coronary interventions (PCIs) using contemporaneous data. BACKGROUND: The 1997 American College of Cardiology (ACC)/American Heart Association task force based their recommendation that interventionists perform > or = 75 procedures per year to maintain competency in PCI on data collected largely in the early 1990s. The practice of interventional cardiology has since changed with the availability of new devices and drugs. METHODS: Data were collected from 1994 through 1996 on 15,080 PCIs performed during 14,498 hospitalizations by 47 interventional cardiologists practicing at the five high volume (>600 procedures per hospital per year) hospitals in northern New England and one Massachusetts-based institution that support these procedures. Operators were categorized into terciles based on their annualized volume of procedures. Multivariate regression analysis was used to control for case-mix. In-hospital outcomes included death, emergency coronary artery bypass graft surgery (eCABG), non-emergency CABG (non-eCABG), myocardial infarction (MI), death and clinical success (> or = 1 attempted lesion dilated to < 50% residual stenosis and no death, CABG or MI). RESULTS: Average annual procedure rates varied across terciles from low = 68, middle = 115 and high = 209. After adjusting for case-mix, clinical success rates were comparable across terciles (low, middle and high terciles: 90.9%, 88.8% and 90.7%, Ptrend = 0.237), as were all the adverse outcomes including death (low-risk patients = 0.45%, 0.41%, 0.71%, Ptrend = 0.086; high-risk patients = 5.68%, 5.99%, 7.23%, Ptrend = 0.324), eCABG (1.74%, 2.05%, 1.75%, Ptrend = 0.733) and MI (2.57%, 1.90%, 1.86%, Ptrend = 0.065). CONCLUSIONS: Using current data, there is no significant relationship between operator volumes averaging > or = 68 per year and outcomes at high volume hospitals. Future efforts should be directed at determining the generalizability of these results.

Changing outcomes in percutaneous coronary interventions: a study of 34,752 procedures in northern New England, 1990 to 1997. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to evaluate the changing outcomes of percutaneous coronary interventions (PCIs) in recent years. BACKGROUND: The field of interventional cardiology has seen considerable growth in recent years, both in the number of patients undergoing procedures and in the development of new technology. In view of recent changes, we evaluated the experience of a large, regional registry of PCIs and outcomes over time. METHODS: Data were collected from 1990 to 1997 on 34,752 consecutive PCIs performed at all hospitals in Maine (two), New Hampshire (two) and Vermont (one) supporting these procedures, and one hospital in Massachusetts. Univariate and multivariate regression analyses were used to control for case mix. Clinical success was defined as at least one lesion dilated to <50% residual stenosis and no adverse outcomes. In-hospital adverse outcomes included coronary artery bypass graft surgery (CABG), myocardial infarction and mortality. RESULTS: Over time, the population undergoing PCIs tended to be older with increasing comorbidity. After adjustment for case mix, clinical success continued to improve from a low of 88.2% in earlier years to a peak of 91.9% in recent years (p trend <0.001). The rate of emergency CABG after PCI fell in recent years from a peak of 2.3% to 1.3% (p trend <0.001). Mortality rates decreased slightly from 1.2% to 1.1% (p trend 0.007). CONCLUSIONS: There has been a significant improvement in clinical outcomes for patients undergoing PCIs in northern New England, including a significant decline in the need for emergency CABG.

Multivariate prediction of in-hospital mortality after percutaneous coronary interventions in 1994-1996. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: Using recent data, we sought to identify risk factors associated with in-hospital mortality among patients undergoing percutaneous coronary interventions. BACKGROUND: The ability to accurately predict the risk of an adverse outcome is important in clinical decision making and for risk adjustment when assessing quality of care. Most clinical prediction rules for percutaneous coronary intervention (PCI) were developed using data collected before the broader use of new interventional devices. METHODS: Data were collected on 15,331 consecutive hospital admissions by six clinical centers. Logistic regression analysis was used to predict the risk of in-hospital mortality. RESULTS: Variables associated with an increased risk of in-hospital mortality included older age, congestive heart failure, peripheral or cerebrovascular disease, increased creatinine levels, lowered ejection fraction, treatment of cardiogenic shock, treatment of an acute myocardial infarction, urgent priority, emergent priority, preprocedure insertion of an intraaortic balloon pump and PCI of a type C lesion. The receiver operating characteristic area for the predicted probability of death was 0.88, indicating a good ability to discriminate. The rule was well calibrated, predicting accurately at all levels of risk. Bootstrapping demonstrated that the estimate was stable and performed well among different patient subsets. CONCLUSIONS: In the current era of interventional cardiology, accurate calculation of the risk of in-hospital mortality after a percutaneous coronary intervention is feasible and may be useful for patient counseling and for quality improvement purposes.

Cause of in-hospital death in 12,232 consecutive patients undergoing percutaneous transluminal coronary angioplasty. The Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Some deaths after percutaneous coronary angioplasty (PTCA) occur in high-risk situations (eg, shock), whereas others are unexpected and related to procedural complications. To better describe the epidemiologic causes of death after PTCA, we undertook a systematic review of all in-hospital PTCA deaths in Northern New England from 1990 to 1993. METHODS: The medical records of 121 patients who died during their acute hospitalization for PTCA were reviewed with a standardized data extraction tool to determine a mode of death (eg, low output failure, arrhythmia, respiratory failure) and a circumstance of death (eg, death attributable to a procedural complication, preexisting acute cardiac disease). Any death not classified as a procedural complication was reviewed by a committee and the circumstance of death assigned by a majority rule. RESULTS: Low-output failure was the most common mode of death occurring in 80 (66.1%) of 121 patients. Other modes of death included ventricular arrhythmias (10.7%), stroke (4.1%), preexisting renal failure (4.1%), bleeding (2.5%), ventricular rupture (2.5%), respiratory failure (2.5%), pulmonary embolism (1.7%), and infection (1.7%). The circumstance of death was a procedural complication in 65 patients (53.7%) and a preexisting acute cardiac condition in 41 patients (33.9%). Women were more likely to die of a procedural complication than were men. CONCLUSION: Procedural complications account for half of all post-PTCA deaths and are a particular problem for women. Other deaths are more directly related to patient acuity or noncardiac, comorbid conditions. Understanding why women face an increased risk of procedural complications may lead to improved outcomes for all patients.

Operator volume and outcomes in 12,998 percutaneous coronary interventions. Northern New England Cardiovascular Disease Study Group.

OBJECTIVES: We sought to determine whether there is a relation between operator volume and outcomes for percutaneous coronary interventions (PCIs). BACKGROUND: A 1993 American College of Cardiology/American Heart Association task force stated that cardiologists should perform > or = 75 procedures/year to maintain competency in PCIs; however, there were limited data available to support this statement. METHODS: Data were collected from 1990 through 1993 on 12,988 PCIs (12,118 consecutive hospital admissions) performed by 31 cardiologists at two hospitals in New Hampshire and two in Maine and one hospital in Massachusetts supporting these procedures. Operators were categorized into terciles based on annualized volume of procedures. Univariate and multivariate regression analyses were used to control for case-mix. Successful outcomes included angiographic success (all lesions attempted dilated to < 50% residual stenosis) and clinical success (at least one lesion dilated to < 50% residual stenosis and no adverse outcomes). In-hospital adverse outcomes included coronary artery bypass graft surgery (CABG), myocardial infarction (MI) and death. RESULTS: After adjustment for case-mix, higher angiographic (low, middle and high terciles: 84.7%, 86.1% and 90.3%, p-trend 0.006) and clinical success rates (85.8%, 88.0% and 90.7%, p-trend 0.025), with fewer referrals to CABG (4.54%, 3.75% and 2.49%, p-trend <0.001), were seen as operator volume increased. There was a trend toward higher MI rates for high volume operators (2.00%, 1.98% and 2.57%, p-trend 0.06); all terciles had similar in-hospital mortality rates (1.09%, 0.96% and 1.05%, p-trend 0.8). CONCLUSIONS: There is a significant relation between operator volume and outcomes in PCIs. Efforts should be directed toward understanding why high volume operators are more successful and encounter fewer adverse outcomes.

Left ventricular dyskinesia reversed by intravenous nitroglycerin: a manifestation of silent myocardial ischemia.

Patients with coronary artery disease (CAD) frequently have left ventricular (LV) wall motion abnormalities in the absence of symptoms. Thirty-one patients with such LV wall motion abnormalities in the absence of symptoms participated in a study of the response of these abnormalities to ascending doses of intravenous nitroglycerin (NTG). In a subgroup of 20 patients the relation between the location of LV wall motion abnormalities and the presence or absence of significant CAD (greater than or equal to 50% diameter reduction), in the vessel supplying the LV region, was assessed. Wall motion improved after intravenous NTG; the ejection fraction increased by 3.7% (mean p less than 0.05) and by 9.4% in the 19 patients who responded. There was no significant increase in heart rate; both LV systolic and end-diastolic pressures decreased minimally (12.5 and 3.5 mm Hg, respectively, p less than 0.05). The ejection fraction response was observed with NTG doses less than or equal to 200 micrograms and no dose-response relation was apparent. In the subgroup subjected to regional wall motion analysis, the presence of dyskinesia was significantly (p = 0.007) associated with the presence of important CAD in a vessel supplying that region. Further, the fact that wall motion improvement after NTG was significantly (p = 0.002) associated supports the concept that silent ischemia results in LV regional wall motion abnormalities, which can be reversed with low dose intravenous NTG.