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[Myocardial infarct with normal coronary vessels: an association with dysfunction of the coronary microcirculation]
D Di Clemente1, A Borghi, G L Morgagni
1Istituto di Patologia Speciale Medica e Metodologia Clinica III, Università degli Studi, Bologna.
Insights
This study investigated acute myocardial infarction (AMI) in patients with normal coronary arteries. Findings suggest microvascular dysfunction, not epicardial spasm, may underlie AMI in these cases.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Acute myocardial infarction (AMI) typically involves coronary artery blockages.
- A subset of AMI patients present with normal coronary arteries, a condition requiring further investigation into underlying mechanisms.
Purpose of the Study:
- To investigate the pathophysiology of AMI in patients with angiographically normal coronary arteries.
- To differentiate between epicardial spasm and microvascular dysfunction as causes of AMI in this specific patient group.
Main Methods:
- Prospective analysis of 128 AMI patients, with 7 female patients meeting criteria for normal coronary arteries.
- Invasive testing including atrial pacing and ergonovine administration.
- Measurement of great cardiac vein flow (GCVF), mean aortic pressure (MAP), anterior coronary resistance (ACR), and myocardial lactate extraction.
Main Results:
- Pacing induced chest pain and ST-segment depression in most patients, without significant GCVF increase.
- All patients demonstrated decreased GCVF, increased ACR, and coronary lactate production during testing.
- Ergonovine testing did not provoke focal coronary artery spasm, but contributed to impaired coronary flow and lactate production.
Conclusions:
- AMI in patients with normal coronary arteries is associated with impaired coronary microvascular function, not epicardial spasm.
- Evidence points towards microvascular dysfunction as the primary mechanism in these cases.
- Further research into microvascular dysfunction in AMI is warranted.
Abstract:
The association of acute myocardial infarction (AMI) with normal coronary arteries was analyzed prospectively. A series of 128 consecutive patients underwent coronary angiography within 1 week from AMI. Seven patients, all females, had no coronary artery lesions and were considered eligible for the study. All 7 patients underwent atrial pacing (10 g/min increments every 2 min), ergonovine testing (E; total dose 0.650 mg i.v.). Great cardiac vein flow (GCVF; thermodilution technique), mean aortic pressure (MAP), anterior coronary resistance (ACR) and myocardial lactate extraction [(Lac art-Lac gcv)/Lac art] were measured at baseline and during testing. Pacing-induced typical chest pain occurred in 5 patients: 4 of them showed concurrent significant (> or = 0.15 mV) ST downsloping. At peak pacing, GCVF increased only by < 50%, or even decreased, in all patients. Baseline lactate extraction (0.13 +/- 0.11) changed to lactate production (-0.15 +/- 0.10) in 7/7 patients. None of the patients showed focal epicardial coronary artery spasm following E. During testing, however, all 7 patients showed decrease in GCVF (110 +/- 47 versus 74 +/- 21; p < 0.005), increase in ACR (0.92 +/- 0.29 versus 1.43 +/- 0.20; p < 0.001), and significant coronary lactate production (-0.18 +/- 0.12). Six patients referred slight to moderate chest pain, which was accompanied by ST downsloping in 4.(ABSTRACT TRUNCATED AT 250 WORDS)