Describing Activity in Primary Percutaneous Coronary Intervention: An Exploration of Denominators

From the HEAT Trial - A Systematic Evaluation of PPCI Activations in Liverpool, Explaining Denominators (HEAT-SEALED)

Adeel Shahzad, MRCP; Christine Mars, Dip HE; Ian Kemp, BA; Rob Cooper, MRCP; Paul Arnold; Claire Roome, MBBS; Keith Wilson; Jim McLenachan, MD; Huon Gray, MD; John Morris, MD; Rod H. Stables, DM


J Invasive Cardiol. 2016;28(6):247-252. 

In This Article

Abstract and Introduction


Background. The provision of primary percutaneous coronary intervention (PPCI) in the emergency management of ST-elevation myocardial infarction (STEMI) is expensive and resource intensive. Accurate data collection is essential not only for outcomes analysis but also to characterize activity and performance for regions, centers, and operators. Inconsistency in the use of denominators currently creates problems in data interpretation.

Objective. To establish a system of denominator groupings, seeking to better describe the range of clinical activity resulting from an unselected series of PPCI activations.

Methods. The HEAT-SEALED pathway designates a key denominator group (n1-n9) to each phase of PPCI activity and identifies a final "destination category" for each patient leaving the pathway. HEAT-PPCI (How Effective are Antithrombotic Therapies in Primary Percutaneous Coronary Intervention) is a true "all-comers" trial and provides an ideal platform to collect data for prospective validation of the pathway. We report data from all PPCI activation events for the HEAT-PPCI trial.

Results. Our findings demonstrate important differences between the sizes of key PPCI denominator groups and hence the potential for variation in reported outcomes depending on the denominator category selected. The main figures are: all activations (n1 = 2490); all suspected MI cases (n4 = 1940; 77.91%); patients in whom angiography was performed (n5 = 1904; 76.46%); cases in which diagnosis was confirmed with a probable culprit lesion (n6 = 1657; 66.54%), and cases with complete PCI success (n9 = 1441; 57.87%).

Conclusion. The HEAT-SEALED pathway offers a practical and comprehensive solution to the problem of describing denominators in STEMI and PPCI. Routine application would facilitate a more consistent and precise description of activity and outcome.


Primary percutaneous coronary intervention (PPCI) is now considered the gold-standard treatment for ST-elevation myocardial infarction (STEMI).[1,2] PPCI activity is expanding as this becomes the dominant treatment modality for emergency reperfusion. In the 12 months between April 2011 and March 2012, a total of 32,439 patients in the United Kingdom were recorded as having a STEMI event.[3] Reperfusion treatment was delivered to 70% of these patients and of these, 95% had PPCI as their index therapy[3] (approximately 330–380 PPCI procedures/million[4]). In the United States, according to the CathPCI registry, the number of STEMI patients receiving PPCI is exceeding 100,000 per year[5–9] (estimated 300–350 PPCI procedures/million[2,7,10]).

The provision of a high-quality PPCI service is a complex and demanding task. This involves public health education and a number of different aspects of emergency care provision – with several, otherwise disparate, agencies and teams involved in delivery. Public health education seeks to encourage an earlier "call for help" to reduce the time interval between the onset of symptoms and presentation. Improvements in the response of emergency medical services (EMS) and the receiving medical teams should help reduce the delays associated with the move to an appropriate facility and the provision of reperfusion therapy.[4] There appears to be a relationship between the quality of service and more favorable outcomes.[2,3,11–15] This has prompted great interest in improving systems and performance with audits and analysis, often coordinated at a national level.[3,16,17]

There is a self-evident need to record accurate data to facilitate clear reporting of patient risk profiles, presentation characteristics, procedural data, and outcomes. There is also a need for consistency in reporting the performance and activity levels of different regions, PPCI centers, and individual operators.

Currently, there is no consistent and agreed system to describe denominators for STEMI. For instance, of all those suffering STEMI, a proportion will die of cardiac arrest and never reach the hospital. Those who do reach the hospital may be unsuitable for reperfusion therapy, and those who are suitable may be taken to the cardiac catheterization laboratory, but may not require PPCI for clinically appropriate reasons. It is therefore difficult to analyze PPCI activity and outcomes, as authors may choose to use different denominators for reported figures. To demonstrate high-volume activity, one might choose to quote the total number of PPCI activations at a center. To reflect more favorable mortality figures, one might restrict the patient population to those with successful reperfusion. These "floating denominators" can make it difficult to interpret and compare reports of PPCI activity and outcome.