Complete Versus Incomplete Angiography Prior to Percutaneous Coronary Intervention in ST-Elevation Myocardial Infarction

Abstract: Objectives. Shorter reperfusion times in ST-elevation myocardial infarction (STEMI) are associated with improved survival. Prehospital strategies have been developed to minimize door-to-balloon (DTB) time, but few strategies within the catheterization laboratory itself have been evaluated. Incomplete angiography (IA) prior to percutaneous coronary intervention (PCI) is undertaken in clinical practice as a means to further reduce DTB time. We sought to determine whether or not those with STEMI who underwent IA prior to PCI had different preprocedural characteristics or post-PCI outcomes. Methods. We retrospectively reviewed patients presenting to our institution between March 2013 and December 2015. Clinical, demographic, and angiographic data were reviewed. The frequency, predictors, and outcomes among those who received IA vs complete angiography (CA) prior to PCI were compared with analysis of variance. Results. Two hundred fifty-six patients were identified; 68 patients (26.6%) underwent IA and 188 patients (73.4%) had CA prior to PCI. Patients who received IA were younger, but no other preprocedural factors were predictive of IA. The practice of IA did vary by operator (range, 0%–47%; P<.01). DTB times were shorter in the IA group (28.1 min vs 37.3 min; P<.01). Overall outcomes, including peak troponin values, length of stay, in-hospital mortality, and discharge ejection fraction did not differ between the groups. Conclusion. IA is associated with shorter DTB times, although in this population was not associated with improvements in short-term outcomes.  

J INVASIVE CARDIOL 2017;29(8):285-288. Epub 2017 March 15.

Key words: acute myocardial infarction, coronary angiography, stenting, outcomes

Coronary reperfusion with percutaneous coronary intervention (PCI) in the setting of ST-segment elevation myocardial infarction (STEMI) improves survival.¹ Minimizing the time from ischemia to reperfusion is associated with reductions in infarct size and overall mortality, and systems of care have been implemented in order to facilitate process efficiency.^2-4 Multiple strategies prior to arrival in the catheterization laboratory have been adopted in an effort to reduce ischemia to reperfusion time, but few studies have evaluated strategies within the catheterization laboratory to further decrease door-to-balloon (DTB) times.^4,5 

Directed angiography of the presumed infarct-related vessel with immediate intervention thereafter may reduce overall DTB time, but this practice precludes evaluation of atherosclerosis in the supposed non-infarct vessel. Although likely faster, incomplete angiography (IA) may be unable to effectively inform the extent (complete or incomplete), type (balloon angioplasty, bare-metal stent, or drug-eluting stent), and manner (percutaneous or surgical) of revascularization. Herein, we sought to identify the incidence of incomplete IA prior to PCI in STEMI, the effect on DTB times, and relevant cardiovascular outcomes. 

Methods

Adult patients undergoing primary PCI for STEMI at The Ohio State University Wexner Medical Center between March 2013 and April 2014 were included in this report. Patients were retrospectively identified from an existing internal database that captures demographic, clinical, procedural, and outcome data for patients with acute coronary syndromes referred for angiography. This study was approved and undertaken in accordance with guidelines from the Institutional Review Board. 

Each angiogram was retrospectively reviewed by a single investigator and deemed complete (CA) or incomplete (IA) based on the performance of left and right coronary angiography (in at least 2 views and 1 view, respectively). The infarct-related artery and PCI vessel(s) were identified independently and later cross-referenced to the procedure report and internal database. 

Statistical analysis. Statistical analysis of nominal data was accomplished with the Chi-square test. Descriptive data are expressed as mean ± standard deviation. Continuous variables were analyzed with analysis of variance, and a statistical significance was set at P<.05. Analysis was performed using SPSS version 12 (SPSS, Inc). 

Results

During the study period, 256 cases were identified. The mean age was 60 years and 73% were male. The most common infarct vessel was right coronary artery (RCA; 52%), while the left anterior descending (LAD; 31%), left circumflex (LCX; 13%), and graft vessels (4%) accounted for the remainder. IA prior to PCI was employed in 68 patients (26.6%) and CA in 188 patients (73.4%). 

Patients receiving IA were younger, although no additional preprocedural factors (infarct vessel, access site, shock on presentation, time from onset to presentation, or presentation to arrival in the catheterization laboratory) were predictive of IA (Table 1). The practice of IA did vary in a statistically significant manner by operator (range, 0%-47%; P<.01) (Figure 1). Revascularization times were significantly shorter in the IA group (DTB: 28.1 min vs 37.3 min; P<.01) (Table 1), and the distribution of revascularization times was similar (Figure 2). 

Overall outcomes, including peak troponin values, length of stay, in-hospital mortality, new-onset heart failure, and discharge ejection fraction did not differ between the groups (Table 2). 

Discussion

Many pre-catheterization lab strategies have been successfully implemented to decrease DTB and a majority of catheterization labs in the United States have met and surpassed the 90-minute benchmark.^5-7 However, there remain ongoing institutional and public health initiatives to further abbreviate the ischemia to reperfusion time.⁸ Within the catheterization laboratory, performing directed angiography of the presumed infarct vessel and then immediate revascularization is one strategy for shortening reperfusion times. The present study has demonstrated that a practice of IA prior to PCI in STEMI is associated with shorter DTB times, but no significant difference in short-term outcomes. 

The clinical practice of IA before PCI in STEMI is common – 37%-46%^9-10 in prior series and 26.6% herein. While IA may be undertaken selectively in situations where more urgent revascularization is thought necessary (shock, anterior MI), these were not more common among the IA group here or elsewhere.^9,10 In fact, the present study is the first to demonstrate a reliable predictor of IA – namely, operator practice. Together with the frequency of IA prior to STEMI, this interoperator variability underscores the need for clarity regarding the appropriateness of its utilization. 

Assuming the goal of IA is to reduce DTB times, available data would suggest it is effective. In the present series, the mean reduction in DTB time was 9.2 min, while others have also reported significant reductions (12-13 min) with IA vs CA.^9,10 Despite these improvements, however, there have been no meaningful differences in short-term outcomes with this strategy. The relationship between DTB times, infarction size, and overall survival is linear, though may plateau as DTB times move below 60 min. An analysis of the STEMI population from the National Cardiovascular Data Registry (NCDR) found an absolute significant decrease in hospital mortality of 0.5% when DTB time was decreased from 60 min to 30 min.¹¹ Additionally, a more recent analysis from the NCDR demonstrated significant risk-adjusted reductions in mortality for every 10-min reduction in DTB time,¹² a decrement that can likely be achieved with an IA vs CA strategy. We and others^9,10 have not observed a difference in mortality with an IA strategy despite significantly shorter DTB times. This may be a reflection of small sample sizes, or variability between the groups unaccounted for in this and other analyses. 

Although the reduced DTB time afforded by IA is desirable, there are possible costs with an IA strategy. One possibility is delayed infarct-vessel revascularization. Among the foremost considerations with an IA strategy is the diagnostic accuracy of the electrocardiogram,^13-15 which may be more variable with inferior-wall STEMI.^16,17 An IA approach may have grave implications if a stable but severe non-culprit lesion is mistaken as the culprit lesion and intervention primarily undertaken. 

Study limitations. The present study was performed at a single institution in retrospective fashion. This limits generalizability and does not account for the selection bias of individual operators. 

Conclusion

This study represents a comparably large series of real-world STEMI patients undergoing alternative forms of angiography prior to coronary intervention. Moreover, it adds to the small but consistent literature that suggests IA is associated with shorter DTB times, but to date, no favorable change in cardiovascular outcomes. Given the frequency of the clinical scenario, the interindividual variability in practice, and the potential for mortality reduction via shorter DTB times in STEMI, evidence-based practice guidelines are warranted. 

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From ¹OhioHealth Heart and Vascular Physicians, Columbus, Ohio; ²Division of Cardiovascular Medicine, The Ohio State University Medical Center, Columbus Ohio; and the ³Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, Ohio.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted November 21, 2016; provisional acceptance given November 24, 2016, final version accepted November 30, 2016.

Address for correspondence: Scott M. Lilly MD, PhD, Ohio State University Heart and Vascular Center, 473 W. 12th Avenue, Suite 200, Columbus, OH 43210-1252. Email: scott.lilly@osumc.edu