Original ArticleNon-ST Elevation Myocardial Infarction with Occluded Artery and its Clinical Implications
Introduction
Non-ST Elevation Myocardial Infarction (NSTEMI) is often thought to be due to incomplete occlusion of the culprit artery whilst ST-Elevation Myocardial Infarction (STEMI) is often thought to be due to complete occlusion of the culprit artery [1], [2], [3], [4], [5], [6]. However, studies have shown that about a quarter of NSTEMI are actually due to complete occlusion of the culprit artery, not dissimilar to the findings of STEMI on coronary angiography [7], [8], [9]. Nonetheless, NSTEMIOA is often treated as less urgent than STEMI. There had been minimal data on the differences between NSTEMI with occluded artery (NSTEMIOA) and NSTEMI with patent artery (NSTEMIPA) in terms of clinical characteristics and outcomes, particularly in the context of early versus late percutaneous revascularisation. The objectives of this study were to investigate the demographics, clinical risk profile, angiographic differences between these two cohorts, and also to investigate the outcomes of NSTEMIOA and NSTEMIPA in terms of the timing of percutaneous revascularisation.
Section snippets
Inclusion and Exclusion Criteria
This study was a single-centre, retrospective, observational study conducted at a community based tertiary hospital with a primary PCI facility. The inclusion criteria for this study were:
- 1.
Acute myocardial infarction (AMI) cases between 01/01/2010 and 30/06/2010 presenting to the Emergency Department or Coronary Care Unit. AMI was defined as the presentation of Acute Coronary Syndrome (ACS) with peak troponin I of >0.03 μg/L and peak CK of >200 IU/L.
- 2.
Diagnosis of NSTEMI in medical record with
Study Population
During the period between 01/01/2010 and 30/06/2010 we identified 192 NSTEMI patients who underwent angiograms. A total of 49 patients were excluded based on exclusion criteria of previous CABG (18), incomplete medical records (20), peak troponin I less than 0.03mcg/L (4) and outpatient instead of inpatient coronary angiography (7). Hence, 143 patients were included in the study. Of these, 46 patients were female (32%) and 97 were male (68%). The mean age of the patients was 64 years old. We
Clinical Outcomes
The data of clinical outcomes are presented in Table 3. In our study cohort no patients reached the end point of death within 12-month follow up period. Overall, our study cohort had a low rate of recurrent MI within 12 months (5.6%). There was no significant difference in the recurrent MI rate between NSTEMIOA and STEMIPA cohorts and their MI-free Kaplan Meier survival plot (Table 3 and Figure 1). There was a trend showing that NSTEMIOA cohort had a higher incidence of heart failure
Timing of Revascularisation
Linear regression analysis showed that there was no correlation between the time delay to PCI and the peak CK level for the whole NSTEMI patient cohort (Pearson Correlation = -0.157, p = 0.199) or for both NSTEMIOA and NSTEMIPA subgroups (Figure 3a and 3b).
Discussion
Our retrospective observational study has shed light on the prevalence and characteristics of NSTEMI patients with occluded arteries as well as the effect of the timing of revascularisation on these patients in accordance with our objectives.
In our study we found that about a quarter of our NSTEMI cohort had occluded arteries, similar to previously conducted studies [7], [8]. From the data that we gathered regarding the patients’ demographic and clinical presentation data we were able to
Conclusion
We found that around a quarter of NSTEMI patients present with occluded arteries. We identified that NSTEMI patients with occluded arteries were more likely to have hypercholesterolaemia, ST changes on admission ECG, multi-vessel disease and the presence of collateral supplies on coronary angiography. Otherwise, there were no other clear differentiating risk profiles, biochemical markers and presentations between the two groups. There were also no significant differences in the clinical outcome
Acknowledgements
We would like to thank The University of Melbourne for the financial support, the Coronary Care Unit and Medical Records Department of Western Health for their assistance.
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