Total Occlusion Post-Myocardial Infarction Intervention Study - TOMIIS

Description:

This study evaluated the effect on left ventricular function of PTCA on an occluded artery late in the course of myocardial infarction (5 days- 6 weeks) after myocardial infarction.

Hypothesis:

PTCA of an occluded artery >6 weeks after Q-wave myocardial infarction would be associated with improved left ventriuclar systolic function.

Study Design

Study Design:

Patients Enrolled: 44
Mean Follow Up: 4 months
Mean Patient Age: Mean 58
Female: 30
Mean Ejection Fraction: The average baseline LVEF was approximately 45% in both groups. At follow-up, patients with a patent infarct-related artery (+9.4 +/- 6.2%) had a greater improvement in LVEF compared to those with an occluded artery (+1.6 +/- 8.8%; p = 0.0096).

Patient Populations:

First Q-wave myocardial infarction within 5 days to 6 weeks and age <80 years.

Exclusions:

1. Canadian Cardiovascular Study Class II or greater post-infarction angina 2. If during a low-level exercise test, the patient developed chest pain with >=2mm ST segment depressions at <6 minutes. 3. Patients with >=50% diameter stenosis in the left main or >70% stenosis in all three major vessels.

Primary Endpoints:

Absolute change in resting left ventricular ejection fraction

Secondary Endpoints:

Patency of the infarct related artery

Drug/Procedures Used:

Eligible patients underwent coronary angiography. Patients with an occluded infarct related artery were randomized to receive PTCA or no PTCA. Follow-up angiography was obtained at 4 months. Left ventricular ejection fraction was obtained at baseline and 4 months.

Concomitant Medications:

Patients receive standard medical therapy after myocardial infarction including aspirin, a beta-blocker an angiotensin-converting enzyme inhibitor.

Principal Findings:

The success rate of the procedure was 72%. At 4 months, the infarct-related artery was patent in 43% of PTCA patients and in 19% of no PTCA patients (p = NS).Reocclusion occurred in 40% of patients after successful PTCA. Secondary analyses showed that at follow-up, patients with a patent infarct-related artery had a greater improvement in LVEF (+9.4 +/- 6.2%) compared to those with an occluded artery (+1.6 +/- 8.8%; p = 0.0096). Baseline ejection fraction also independently predicted improvement in left ventricular ejection fraction (p = 0.0001). Patients with the lowest ejection fractions had the greatest improvement in function (p<0.0001).

Interpretation:

This randomized pilot study evaluated the strategy of performing PTCA an occluded infarct-related artery late in the course of myocardial infarction (5 days -6 weeks) in low/intermiediate risk patients. This study suggests that sustained patency of the infarct related artery is associated with an improvement in left ventricular systolic function. The small sample size limits the conclusions that can be drawn from this study. This pilot study was performed prior to the widespread use of stents during PCI, as evidenced by the high reocclusion rate by 4 months. In addition, medical therapy including Glycoprotein IIB/IIA receptor antagonists and/or cholesterol lowering medications were not routinely used. Before a strategy can be routinely adopted of performing PCI on totally occluded arteries in low risk patients who are late in the course of myocardial infarction, further studies with larger sample sizes and modern revasularization techniques and medications are needed.

References:

Dzavik V, Beanlands DS, et al. Effects of late percutaneous transluminal coronary angioplasty of an occluded infarct-related coronary artery on left ventricular function in patients with a recent (< 6 weeks) Q-wave acute myocardial infarction (Total Occlusion Post-Myocardial Infarction Intervention Study [TOMIIS]--a pilot study). Am J Cardiol 1994 May 1;73(12):856-61.

Clinical Topics: Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Myocardial Infarction, Follow-Up Studies, Coronary Angiography, Ventricular Function, Left, Stroke Volume, Systole, Stents


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