Acute Balloon Angioplasty vs. Traditional Early Invasive Treatment of Non-ST-Elevation Myocardial Infarction

The purpose of this study is:

A) To determine whether patients with a certain type of heart attack (NSTEMI) can be reliably diagnosed in an ambulance using telemedicine. This is mandatory if NSTEMI patients in the future are to be treated with acute balloon angioplasty (primary PCI).

B) To evaluate whether primary PCI compared with the current regimen of initial medical stabilization and sub-acute PCI results in reduction of infarct-size in NSTEMI-patients.

Primary PCI versus Traditional Early Invasive Treatment of Patients presenting with NSTEMI

Patients with NSTEMI are currently admitted for initial evaluation and stabilization at local hospitals. An intensive antithrombotic treatment is initiated and after 3 - 7 days of "cooling-off" the patients are referred to an invasive centre for coronary angiography and possibly PCI or CABG - this is known as the early invasive approach. Some of these patients represent a high-risk sub-group with occluded or sub-occluded coronary arteries who might benefit from very early revascularization.

Study Aims

1. To investigate if it is technically feasible to diagnose patients with NSTEMI in the pre-hospital setting and reroute them to an invasive heart centre for primary PCI in a timely manner.
2. To estimate area at risk (AAR = the part of cardiac muscle tissue at risk of infarction) and final infarct size (FIS) in patients referred for primary PCI and patients undergoing the traditional "early invasive" treatment, respectively.
3. To investigate whether Primary PCI in patients with NSTEMI results in a shorter duration of the primary admission, fewer rehospitalizations with reinfarction and acute heart failure and a briefer overall "sick leave" within a year from the index admission.

Methods

In this study 300 consecutive patients with symptoms, clinical signs and ECG changes (≥4mm cumulated or ≥ 2mm ST-segment depression (horizontal or descending) in two associated leads) suggesting significant NSTEMI are randomized for one of two strategies, either (A) usual early invasive treatment (coronary angiography and possibly PCI after 3 days) or (B) direct referral (rerouting) to primary PCI at an invasive heart centre (Skejby).

All patients undergo myocardial perfusion imaging at admission for PCI and again after 30 days to estimate AAR, FIS and possible myocardial salvage.

All patients undergo cardiac MRI on the 7th day after admission for determination of AAR and FIS.

The study is a randomized controlled study; it has been approved by the local ethics committee.

Primary outcome measures are specified above

If the study confirms that it is possible to diagnose and re-route NSTEMI patients for primary PCI with an acceptable diagnostic accuracy, then a larger scale mortality study will be planned. Furthermore, the present study will provide valuable information regarding AAR and FIS in NSTEMI-patients which may be of value for planning larger-scale, scintigraphic studies and for the possible future use of a single MRI scan to determine AAR and FIS.

Eligibility Criteria:
Inclusion Criteria:

1. Patients with symptoms and signs of NSTEMI and significant ECG changes (Either ≥4mm cumulated ST-segment depression (horizontal or descending), or ≥2mm ST-segment depression (horizontal or descending) in two associated leads)and/or patients with positive biomarkers for myocardial infarction (troponin T) measured in the ambulance (prehospital measurement of biomarkers).
2. Age above 18 years.
3. Tentative diagnosis made pre-hospitally.

Exclusion Criteria:

1. Severe mental or psychiatric disease (eg. psychosis, dementia, bipolar disorder or depression) as well as other conditions making it impossible to obtain informed consent.
2. Prior CABG (Coronary artery bypass graft) operation.
3. Patients with ST-depression presumed to be caused by tachycardia or cardiac hypertrophy.