PCI in modern cardiology: a shift from chronic stable patients to acute coronary syndromes

Widimsky P.

The COURAGE and MASS II trials versus acute coronary syndromes trials have helped to evaluate the role of PCI should have in modern cardiology.
PCI does not improve prognosis in chronic stable coronary artery disease because the natural course is generally very good and because no culprit lesion exists in chronic stable patients.
PCI improves prognosis in acute coronary syndromes on the other hand because the culprit lesion can be identified by angiography in most patients. PCI centers should focus their resources (both human and financial) mainly on the treatment of acute coronary syndromes.

I - The Courage Trial

A) Results

DThe COURAGE trial (1) randomised 2287 patients with chronic stable coronary artery disease (angiographically at least one stenosis >70%, objective evidence of ischemia) to either initial PCI strategy (+ optimal medical therapy) or initial optimal medical therapy (with later PCI only for progressive / persisting symptoms). The key findings are in table 1.

Table 1: The COURAGE trial key findings

The trial conclusion is that patients with chronic stable coronary artery disease should be initially treated by the optimal medical therapy alone. PCI is indicated when symptoms cannot be controlled by this optimal medical therapy - in approximately one third of patients only.

The trial conclusion is applicable only to patients with no or mild to moderate symptoms: 42% of the trial patients had angina CCS class 0-I and 37% patients CCS class II. Only 21% patients had class III angina and class IV angina was exclusion criterion.

B) Implications

Several previous trials (2-5) had already failed to show any prognostic benefit from elective PCI performed in patients with chronic stable coronary artery disease, yet the COURAGE trial triggered hot discussions about its results and their implementation. I strongly believe that these discussions should also include the results of trials with PCI done for acute coronary syndromes (6-10).

Only when we analyse the data of both acute and chronic forms of coronary artery disease, can we properly evaluate the role of PCI in modern cardiology. While 85% of all PCI procedures done in the United States in 2004 were still done for chronic stable forms of coronary artery disease (11), many European countries' practice already reflected these data and acute coronary syndromes today represent over 50% of their PCI case load. E.g. 62% of PCI procedures in the Czech Republic 2006 were done for acute coronary syndromes (34% for STEMI, 28% for non-STE ACS) and only 38% for chronic stable coronary disease. In our center elective PCI for chronic stable angina represents today only cca 25-30% of all PCI procedures, 70-75% being done for acute coronary syndromes.

II - MASS II

Another randomised trial, MASS II (12) compared 5 years outcomes after CABG, PCI and optimal medical therapy alone in 611 patients with multivessel disease (single vessel disease was exclusion criterion, thus the MASS II patients had higher baseline risk when compared to the COURAGE patients). Bypass surgery resulted in the lowest rates of death (12,8% CABG vs. 15,5% PCI vs. 16,2% medical therapy), myocardial infarction (8,3% vs. 11,2% vs. 15,3%) and reintervention (3,5% vs. 32,2% vs. 24,2%) during the 5 year follow-up.

Conclusion

Overall, these data suggest that, even if CABG is currently considered the standard of care for most patients with left main stenosis, PCI with DES implantation may be a reasonable alternative in an increasing number of subsets. As for settings where several types of treatment are available, a multidisciplinary team is essential to ensure the highest likelihood that the most balanced advice and best treatment options are offered to patients with left main coronary artery disease.

Table 2 summarises the COURAGE and MASS II findings with a focus on the natural course of chronic forms of CAD vs. risk of periprocedural complications related to PCI

Conclusion

PCI does not improve prognosis in chronic stable coronary artery disease : Why?

• The natural course is generally very good in this setting, especially with modern medical therapy. It is thus difficult to improve it further by any mechanical intervention
• The small difference between the low natural vs. low periprocedural risk of death, (re-) infarction or stroke increases the impact of any periprocedural complication on the result of any comparative study (by decreasing the potential benefit from the intervention). See table 2, chronic stable CAD column: the risk of death after PCI is similar to the risk of death with optimal medical therapy alone.
• No culprit lesion exists in chronic stable patients. PCI site is „blind“ in chronic stable patients. Nobody knows, which coronary plaque in the stable patient will become unstable in future – most likely it will not be the plaque with highest degree of angiographic stenosis. The „plaque sealing“ concept of PCI cannot work in chronic stable patients, because theoretically all existing plaques should be „sealed“ by full metal jacket of all coronary tree......

PCI improve prognosis in acute coronary syndromes : Why ?

• The natural course is generally poor in this setting, despite modern medical therapy. It is thus possible to improve it further by a mechanical intervention, which opens the occluded artery and/or stabilizes the unstable plaque.
• The difference between the high natural vs. low periprocedural risk is large (see table 2, ACS column). The risk of death, (re-) infarction or stroke as periprocedural complication in this setting is similarly low as in chronic stable patients. Thus, the a comparative study is more lilely to show the benefit from the intervention.
• The culprit lesion can be identified by angiography in most patients with acute coronary syndromes. Thus, the unstable coronary plaque can be angiographically recognized and treated (PCI is not „blind“ in acute coronary syndromes). The "plaque sealing“ concept of PCI works perfectly well in acute coronary syndromes (opposite to chronic stable disease). This difference could be compared with stomatology: PCI in acute coronary syndromes is similar to treating the acute dental pain: the acutely ill tooth (plaque) is sealed and the patient is fine untill the next tooth (plaque) will become unstable and needs re-intervention. Between these exacerbations dental hygiene (medical therapy) is the best treatment.

Lessons to be learned

• PCI centers should focus its resources (both human and financial) mainly on the treatment of acute coronary syndromes, where PCI was clearly shown to improve the patients outcomes
• Patients with chronic stable coronary artery disease should be initially treated medically and PCI should be performed upon patient’s request (when medical therapy failed) to aleviate the symptoms (patients should be informed, that PCI will not prolong their life in this setting)
• The proportion of acute / elective PCI cases can be used to evaluate the effectivity of health care systems (regional, national, local): PCI for acute coronary syndromes should exceed 50% of all PCI workload (probably should be around 60-70%) in a modern PCI center.
• Bypass surgery remains a viable alternative for chronic stable patients with multivessel coronary artery disease.

References

1. Boden WE, O’Rourke RA, Teo KK for the COURAGE trial Research Group. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med 2007; 356: 1503-16.
2. Parisi AF, Folland ED, Hartigan P. A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. N Engl J Med 1992;326:10-16.
3. Pitt B, Waters D, Brown WV, et al. Aggressive lipid-lowering therapy compared with angioplasty in stable coronary artery disease. N Engl J Med 1999;341:70-76.
4. Henderson RA, Pocock SJ, Clayton TC, et al. Seven-year outcome in the RITA-2 trial: coronary angioplasty versus medical therapy. J Am Coll Cardiol 2003;42:1161-1170.
5. Katritsis DG, Ioannidis JP. Percutaneous coronary intervention versus conservative therapy in nonacute coronary artery disease: a meta-analysis. Circulation 2005;111:2906-2912.
6. Keeley EC, Boura JA, Grines CL. Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomised trials. Lancet 2003;361:13-20.
7. Fragmin and Fast Revascularisation during InStability in Coronary artery disease Investigators. Invasive compared with non-invasive treatment in unstable coronary-artery disease: FRISC II prospective randomised multicentre study. Lancet 1999;354:708-715.
8. Fox KA, Poole-Wilson PA, Henderson RA, et al. Interventional versus conservative treatment for patients with unstable angina or non-ST-elevation myocardial infarction: the British Heart Foundation RITA 3 randomised trial: Randomized Intervention Trial of unstable Angina. Lancet 2002;360:743-751.
9. Mehta SR, Cannon CP, Fox KA, et al. Routine vs selective invasive strategies in patients with acute coronary syndromes: a collaborative meta-analysis of randomized trials. JAMA 2005;293:2908-2917.
10. Widimsky P, Bilkova D, Penicka M, Novak M, Lanikova M, Porizka V, Groch L, Zelizko M, Budesinsky T, and Aschermann M on behalf of the PRAGUE Study Group Investigators. Long-term outcomes of patients with acute myocardial infarction presenting to hospitals without catheterization laboratory and randomized to immediate thrombolysis or interhospital transport for primary percutaneous coronary intervention. Five years’ follow-up of the PRAGUE-2 trial. Eur Heart J 28; 2007: 679-84.
11. Feldman DN, Gade CL, Slotwiner AJ, et al. Comparison of outcomes of percutaneous coronary interventions in patients of three age groups (<60, 60 to 80, and >80 years) (from the New York State Angioplasty Registry). Am J Cardiol 2006;98:1334-1339.
12. Hueb W, Lopes NH, Gersh BJ, Soares P, Machado LAC, Jatene FB, Oliveira SA, Ramires JAF. Five-year follow-up of the Medicine, Angioplasty or Surgery Study (MASS II). Circulation 2007; 115: 1082-9.