How much do we gain by reducing time to reperfusion therapy?

Time-to-Treatment for Myocardial Infarction: Barriers and Facilitators Perceived by American Indians in Three Regions

Early recognition of acute myocardial infarction (MI), followed by prompt emergency care, improves patient outcomes. Among rural American Indian (AI) populations there are disparities in access to care for MI and processes of care, resulting in poor MI-related health outcomes compared to the general population. We sought to gain an understanding of barriers related to MI time-to-treatment delays using a qualitative approach. We conducted semi-structured interviews and focus groups with AI key informants and community members in three Indian Health Service regions. Major barriers to care included long travel distance to care and lack of supporting infrastructure; distrust of the health care system; low overall literacy and basic health literacy; priority of family care-giving; and lack of specialized medical facilities and specialists. Findings suggest that improved time-to-treatment facilitators include educating the local community about the causes and consequences of MI and culturally-sensitive health communication, as well as addressing the quality of local systems of care and the community's perception of these systems. Pursuing these strategies may improve quality of care and reduce MI-related morbidity and mortality in rural AI populations.

MEASURING THE EMS PATIENT ACCESS TIME INTERVAL andTHE IMPACT OF RESPONDING TO HIGH-RISE BUILDINGS

OBJECTIVES

To measure the patient access time interval and characterize its contribution to the total emergency medical services (EMS) response time interval; to compare the patient access time intervals for patients located three or more floors above ground with those less than three floors above or below ground, and specifically in the apartment subgroup; and to identify barriers that significantly impede EMS access to patients in high-rise apartments.

METHODS

An observational study of all patients treated by an emergency medical technician paramedics (EMT-P) crew was conducted using a trained independent observer to collect time intervals and identify potential barriers to access.

RESULTS

Of 118 observed calls, 25 (21%) originated from patients three or more floors above ground. The overall median and 90th percentile (95% confidence interval) patient access time intervals were 1.61 (1.27, 1.91) and 3.47 (3.08, 4.05) minutes, respectively. The median interval was 2.73 (2.22, 3.03) minutes among calls from patients located three or more stories above ground compared with 1.25 (1.07, 1.55) minutes among those at lower levels. The patient access time interval represented 23.5% of the total EMS response time interval among calls originating less than three floors above or below ground and 32.2% of those located three or more stories above ground. The most frequently encountered barriers to access included security code entry requirements, lack of directional signs, and inability to fit the stretcher into the elevator.

CONCLUSIONS

The patient access time interval is significantly long and represents a substantial component of the total EMS response time interval, especially among ambulance calls originating three or more floors above ground. A number of barriers appear to contribute to delayed paramedic access.

Conducting an economic analysis to assess the electrocardiogram's value

BACKGROUND AND PURPOSE

Health economic analyses seek to assess the relative value (cost vs health benefit trade-offs) of medical technologies. However, these methods have been underused in studies of the electrocardiogram (ECG).

METHODS

We develop a framework for the economic evaluation of the ECG as a decision support tool within broader treatment strategies. We then apply this framework to the development of an economic study protocol for the Prehospital Wireless Transmission of Electrocardiograms to a Cardiologist via a Hand-held Device Multicenter study.

RESULTS

Our framework defines key cost-effectiveness concepts and describes alternative methods for estimating medical costs and health benefits. We demonstrate how this framework has been applied to develop the Prehospital Wireless Transmission of Electrocardiograms to a Cardiologist via a Hand-held Device Multicenter economic protocol.

CONCLUSIONS

The conduct of health economic studies alongside ECG clinical studies could provide important information for those seeking to promote newer ECG applications that require significant financial investments.

[Clinical and therapeutic specificities of myocardial infarction in patients with peripheral arterial disease: the USIC 2000 registry]

OBJECTIVE

Several studies underlined the worse prognosis of myocardial infarction (MI) among patients with peripheral arterial disease (PAD). We sought to describe the presentation and management modalities of a cohort of PAD patients presenting an acute MI, compared to those without PAD.

MATERIALS AND METHODS

The USIC 2000 registry, a nationwide database on all patients admitted to a CCU for an acute MI < 48 hours in France in November 2000 was used for this study.

RESULTS

Among the 2311 patients included, PAD was reported in 215 subjects (9.3%). In multivariate analysis, the following factors were positively related to the presence of PAD (P < or = 0.05): age >75 y (OR = 2.3), diabetes (OR = 2.0), hypertension (OR = 1.4), active smoking (OR = 4.6), renal failure (OR =3.1), and treatments with antiplatelets (OR = 3.9), anti-vitamin K (OR = 1.9), statins (OR = 1.7) and low molecular weight heparins (OR = 6.8). By introducing the data concerning the arrival in CCUs in the model, the following factors were also significantly more frequent among PAD patients: male sex (OR = 1.6), past history of coronary artery disease (OR = 2.2), left bundle branch block (OR = 1.8) and late management >6 hours (OR = 1.4). Conversely, ST-segment elevation was less frequent (OR = 0.7). When the CCU stay data were introduced in the model, a lower rate of coronary stenting (OR = 0.7) and betablockers use within 48 hours of admission (OR = 0.6) were noted.

CONCLUSION

Beyond the presence of PAD per se, several particularities do exist, especially the coexistence of a high number of pejorative factors and an under-utilization of treatments presenting prognostic benefits.

Prehospital thrombolysis--calculated health benefit for catchment population of one hospital

The health benefit of thrombolysis in acute myocardial infarction is greatest when patients are treated soon after onset of symptoms. One approach to reducing treatment delay is to give thrombolysis before the patient reaches hospital. When an ambulance trust proposed a prehospital thrombolysis service, local commissioners requested an estimate of its possible health impact. Clinical audit and ambulance trust data were obtained for 165 patients who received thrombolysis for acute myocardial infarction in the coronary care unit of a local hospital in one year. This information was then used to estimate the health impact of prehospital thrombolysis in the local population in a mathematical model derived from the results of trials comparing prehospital and hospital thrombolysis. The best predicted local health benefit from the proposed prehospital thrombolysis service is that, if 45 minutes can be cut off the call-to-needle time, 61 cases of acute myocardial infarction need to be treated to save one additional life at 35 days. By use of published research data, the health benefits of prehospital thrombolysis can be estimated for a local population. Variables in the treatment population and ambulance service will influence the size of the health benefit that can be achieved.

Prehospital Thrombolysis—Calculated Health Benefit for Catchment Population of One Hospital

The health benefit of thrombolysis in acute myocardial infarction is greatest when patients are treated soon after onset of symptoms. One approach to reducing treatment delay is to give thrombolysis before the patient reaches hospital. When an ambulance trust proposed a prehospital thrombolysis service, local commissioners requested an estimate of its possible health impact. Clinical audit and ambulance trust data were obtained for 165 patients who received thrombolysis for acute myocardial infarction in the coronary care unit of a local hospital in one year. This information was then used to estimate the health impact of prehospital thrombolysis in the local population in a mathematical model derived from the results of trials comparing prehospital and hospital thrombolysis.

The best predicted local health benefit from the proposed prehospital thrombolysis service is that, if 45 minutes can be cut off the call-to-needle time, 61 cases of acute myocardial infarction need to be treated to save one additional life at 35 days.

By use of published research data, the health benefits of prehospital thrombolysis can be estimated for a local population. Variables in the treatment population and ambulance service will influence the size of the health benefit that can be achieved.

Are we underestimating the full potential of early thrombolytic treatment in patients with acute myocardial infarction?

Use of the Boersma curve in order to describe the beneficial effect of thrombolytic treatment at different treatment delays seems questionable, because the curve may underestimate the favourable prognostic effects of early thrombolysis in patients with acute myocardial infarction

Time course and determinants of left ventricular function recovery after primary angioplasty in patients with acute myocardial infarction

OBJECTIVES

We sought to evaluate the importance of time in relation to treatment, time course and determinants of recovery of left ventricular (LV) function in patients with acute myocardial infarction (AMI) undergoing primary percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Myocardial salvage has been shown to be dependent on the time elapsed from the onset of AMI to reperfusion.

METHODS

Left ventricular function was evaluated at hospital admission, after angioplasty, at 24 h and 6 months by both echocardiography and angiography and at 1, 7, 30, 90 and 180 days by echocardiography in 101 consecutive patients.

RESULTS

Patients were allocated to three groups according to interval between symptom onset and angioplasty: <2 h (group A), 2 to 4 h (group B) and >4 h (group C). Patients in groups A and B showed a progressive improvement of LV function between day 7 and day 90, which became statistically significant at day 30 (p < 0.01). No LV function changes were noted in group C patients. Thrombolysis In Myocardial Infarction (TIMI) flow grade <3 at 24 h was not associated with any significant change in LV volume and function during the six-month follow-up period. Restenosis, when associated with TIMI flow grade 3 in the infarct-related vessel, did not influence LV function. Flow grade <3 of the infarct-related artery was not associated with any improvement of cardiac events independently from the time to treatment at the initial procedure.

CONCLUSIONS

Patients undergoing primary PTCA for AMI have a good recovery of LV function if TIMI flow grade 3 is restored within 4 h. Coronary angioplasty limits further remodeling of the LV in patients treated after 4 h.

Influence of treatment delay on long-term left ventricular function in patients with acute myocardial infarction successfully treated with primary angioplasty

BACKGROUND

Myocardial salvage has been shown to be dependent on the time elapsed from the onset of acute myocardial infarction (AMI) to reperfusion. The aim of this study was to evaluate the importance of time to reperfusion for left ventricular function recovery after primary angioplasty (percutaneous transluminal coronary angioplasty [PTCA]) for AMI.

METHODS

Ninety-five patients undergoing long-term successful PTCA for AMI were studied. Echocardiography was performed before and 3, 7, 30, 90, and 180 days after PTCA. End-diastolic volume index (EDVI) and end-systolic volume index (ESVI), ejection fraction, and left ventricular wall motion score index (WMSI) were evaluated.

RESULTS

Patients were divided into group A, 23 patients reperfused within 2 hours; group B, 32 patients reperfused between 2 and 4 hours; group C, 22 patients reperfused between 4 and 6 hours; and group D, 18 patients reperfused between 6 and 12 hours. Both EDVI and ESVI were reduced in groups A and B at 90 days. Groups C and D did not show any changes of EDVI and ESVI at any stage throughout the study. Ejection fraction improved only in groups A and B at 30, 90, and 180 days. At study entry, WMSI was similar in all groups. After 7 days, in group A and in group B, WMSI was improved, no changes were observed in group C, and a mild deterioration was observed in group D at 3 and 7 days. Subsequent evaluations showed progressive improvement of WMSI in all groups.

CONCLUSIONS

Myocardial salvage is achieved only in patients revascularized within 4 hours from AMI onset. However, revascularization after 6 hours may be worthwhile by preventing ventricular remodeling.

Factors associated with delay in reperfusion therapy in elderly patients with acute myocardial infarction: analysis of the cooperative cardiovascular project

BACKGROUND

Many elderly patients with an acute myocardial infarction (AMI) do not receive thrombolysis within 30 minutes of hospital arrival as recommended by the American College of Cardiology/American Heart Association Guidelines. We sought to identify factors associated with delay in administration of thrombolysis after arrival to the hospital in these patients and to determine whether this delay is associated with increased mortality rates.

METHODS AND RESULTS

By using the Cooperative Cardiovascular Project database, we identified patients who received thrombolysis for an AMI. The patients were stratified into groups by time to thrombolysis after hospital arrival. Among a cohort of 17,379 patients, 22.2% received thrombolysis in the first 30 minutes after hospital arrival. Patients treated after the first 30 minutes were more likely to be older, be female, be diabetic, have a history of hypertension or heart failure, and have less marked ST elevation. They were also more likely to be admitted to smaller hospitals with a lower volume of AMIs and to hospitals without a cardiac catheterization laboratory. The 30-day mortality rate was significantly lower for patients treated within the first 30 minutes. After adjustments were made for clinical and hospital characteristics, delays in therapy beyond 30 and 90 minutes were associated with an increase in 1-year mortality rates of 9% and 27%, respectively, compared with delays for patients treated within 30 minutes.

CONCLUSIONS

After hospital arrival, time to treatment with thrombolytic therapy is longer than recommended in a significant proportion of patients. Clinical characteristics and institutional factors are associated with the delay in treatment. The more rapid treatment of appropriate elderly patients with an AMI probably will reduce mortality rates.

Early diagnosis of acute myocardial infarction in patients without ST-segment elevation

Early identification of acute myocardial infarction (AMI) is necessary to initiate appropriate treatment. In patients presenting without ST-segment elevation, diagnosis is often dependent on the presence of elevated myocardial markers. This study examines the ability of serial MB mass alone and in combination with myoglobin in diagnosing AMI in patients without ST-segment elevation within 3 hours of presentation. In all, 2,093 patients were admitted and underwent serial marker analysis using myoglobin, creatine kinase (CK), and CK-MB at 0, 3, 6, and 8 hours. AMI was diagnosed by a CK-MB > or =8.0 ng/ml and a relative index (RI) (CK-MB x 100/total CK) > or =4.0. A total of 186 patients (9%) were diagnosed with AMI. The optimal diagnostic strategy was an elevated CK-MB + RI on the initial or 3-hour sample or at least a twofold increase in CK-MB without exceeding the upper range of normal over the 3-hour time period (sensitivity 93%, specificity 98%). The combination of an elevated CK-MB + RI or myoglobin on the initial or 3-hour sample had a sensitivity of 94%, although specificity was significantly lower, at 86%. Sensitivities and specificities after exclusion of the 242 patients with ischemic electrocardiographic changes were essentially unchanged. We conclude that most patients with AMI presenting with nondiagnostic electrocardiograms can be diagnosed within 3 hours of presentation.

Ten-year follow-up of the first megatrial testing thrombolytic therapy in patients with acute myocardial infarction: results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto-1 study. The GISSI Investigators

BACKGROUND

We conducted a 10-year follow-up of the 11 712 patients with acute myocardial infarction randomized in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto-1 study, the first large trial assessing thrombolytic therapy.

METHODS AND RESULTS

Information on survival at 10 years was obtained for the 93% of all randomized patients through the census offices of their towns of residence. The difference in survival produced by streptokinase and sustained up to 1 year was still significant at 10 years (log-rank test, P=0.02), with the absolute benefit of 19 (95% CI 1 to 37) lives saved per 1000 patients treated. The time dependence of the extent of the benefit was confirmed, as the higher mortality rate reductions found in patients treated earlier were still present at 10 years. In the overall population, most of the benefit was obtained before hospital discharge (RR 0.81, 95% CI 0.72 to 0.90), since no difference in survival between thrombolyzed and control patients discharged alive was found at 10 years (RR 0.98, 95% CI 0.90 to 1.06). However, a slight albeit nonsignificant divergence of the survival curves of patients randomized within the first hour was observed [90 (95% CI 34 to 146) lives saved per 1000 at 10 years versus 72 (95% CI 37 to 107) lives saved at hospital discharge].

CONCLUSIONS

The benefits of a single intravenous infusion of 1.5 million units of streptokinase in prolonging survival of patients with acute myocardial infarction is sustained up to 10 years, with a still-evident trend in favor of the patients admitted earlier.

Evaluation of a weight-adjusted single-bolus plasminogen activator in patients with myocardial infarction: a double-blind, randomized angiographic trial of lanoteplase versus alteplase

BACKGROUND

Lanoteplase (nPA) is a rationally designed variant of tissue plasminogen activator with greater fibrinolytic potency and slower plasma clearance than alteplase.

METHODS AND RESULTS

InTIME (Intravenous nPA for Treatment of Infarcting Myocardium Early), a multicenter, double-blind, randomized, double-placebo angiographic trial, evaluated the dose-response relationship and safety of single-bolus, weight-adjusted lanoteplase. Patients (n=602) presenting within 6 hours of acute myocardial infarction were randomized and treated with either a single-bolus injection of lanoteplase (15, 30, 60, or 120 kU/kg) or accelerated alteplase. The primary objective was to determine TIMI grade flow at 60 minutes. Angiographic assessments were also performed at 90 minutes and on days 3 to 5. Follow-up was continued for 30 days. Lanoteplase achieved its primary objective, demonstrating a dose-response in TIMI grade 3 flow at 60 minutes (23.6% to 47.1% of subjects, P<0. 001). Similar results were observed at 90 minutes (26.1% to 57.1%, P<0.001). At 90 minutes, coronary patency (TIMI 2 or 3) increased across the dose range up to 83% of subjects at 120 kU/kg lanoteplase compared with 71.4% with alteplase. Thus, at this dose, lanoteplase was superior to alteplase in restoring coronary patency (difference, 12%; 95% CI, 1% to 23%). The early safety experience in this study suggests that lanoteplase was well tolerated at all doses with safety comparable to that of alteplase.

CONCLUSIONS

Lanoteplase, a single-bolus, weight-adjusted agent, increased coronary patency at 60 and 90 minutes in a dose-dependent fashion. Coronary patency at 90 minutes was achieved more frequently with 120 kU/kg lanoteplase than alteplase. In this study, safety with lanoteplase and alteplase was comparable. InTIME-II, a worldwide mortality trial, will evaluate efficacy and safety with this promising new agent.

Influence of treatment delay on infarct size and clinical outcome in patients with acute myocardial infarction treated with primary angioplasty

OBJECTIVES

The purpose of this analysis was to determine the influence of an additional treatment delay inherent in transfer to an angioplasty center for primary angioplasty of patients with acute myocardial infarction who are first admitted to hospitals without angioplasty facilities.

BACKGROUND

Several randomized trials have demonstrated the benefits of primary angioplasty in acute myocardial infarction. In recent years, increasing numbers of patients with myocardial infarction, initially admitted to hospitals without angioplasty facilities are transported to our hospital for primary angioplasty. However, the additional delay due to the transport may have a deleterious effect on infarct size and clinical outcome.

METHODS

In a three-year period (December 1993 to November 1996), 207 consecutive patients who were transferred for primary angioplasty were analyzed in a matched comparison with non-transferred patients. Matching criteria were age, sex, infarct location, presentation delay and Killip class.

RESULTS

Patients who were transferred had an additional median delay of 43 min. This resulted in a more extensive enzymatic infarct size and a lower ejection fraction measured at 6 months. The rate of angioplasty success defined as TIMI grade 3 flow, and the 6-month mortality rate (7%) were comparable in both groups.

CONCLUSIONS

The additional delay had a deleterious effect on myocardial salvage, reflected by a larger infarct size and a lower left ventricular function. However, the patency rate and 6-month clinical outcome were not affected by this delay.

Prehospital-initiated thrombolysis

OBJECTIVE

To evaluate the feasibility, safety, and efficacy of prehospital-initiated thrombolysis in decreasing the mortality rate due to acute myocardial infarction.

DATA SOURCES

English-language clinical studies, abstracts, and review articles identified from MEDLINE searches and bibliographies of identified articles. Epidemiologic data were extracted from the Internet.

STUDY SELECTION

Eight randomized clinical trials and two meta-analyses that compared prehospital-initiated thrombolysis with in-hospital-initiated thrombolysis.

DATA EXTRACTION

Pertinent studies were selected and the data were synthesized into a review format.

DATA SYNTHESIS

Early reperfusion of an infarct-related coronary artery is associated with lower mortality rates. Most of the delay in initiating treatment is caused by patient delay rather than transport delay or hospital delay. In addition, more than 30% of eligible patients do not receive thrombolytic therapy. Prehospital initiation of thrombolysis has been evaluated as a means of decreasing hospital delay and increasing the number of eligible patients receiving thrombolysis. Clinical trials document that prehospital-initiated thrombolysis is feasible and safe, and saves time. Of the eight randomized trials, three demonstrated a decrease in either cardiac or total mortality with prehospital thrombolysis. All studies were limited by relatively small sample sizes. Two published meta-analyses suggest a 16-17% reduction in mortality with prehospital thrombolysis. In the US, prehospital thrombolysis is not routinely recommended due to medical issues related to diagnostic accuracy and monitoring, legal concerns, and economic implications. Additional strategies, such as community-wide education and prehospital diagnostic electrocardiograms (ECGs), are being studied.

CONCLUSIONS

In clinical trials, prehospital-initiated thrombolytic therapy was shown to be safe and probably more effective than in-hospital administration of thrombolytic therapy, but this has not proven feasible in the US at this time. Despite time-savings by decreasing treatment delay with prehospital-initiated thrombolysis, patient delay still persists and accounts for the majority of delay. Future investigations will center on increasing the number of patients treated with thrombolytic agents through patient education, in-patient and out-patient programs that rapidly identify eligible patients, as well as prehospital diagnostic ECGs.