Research Review: The Predictors of a Good Benefit From PCI

QUESTION: is nuclear myocardial perfusion scintigraphy useful in predicting an increase in exercise capacity after coronary artery revascularization using percutaneous coronary intervention (PCI)?

BACKGROUND: Since the Courage Trial, there remains doubt over which patients should undergo coronary artery revascularization using percutaneous coronary intervention. In patients with stable angina, PCI has not been shown to be associated with a survival benefit over modern medical therapy. Furthermore, complications from PCI are associated with a risk of morbidity of about 0.25% and risk of mortality of about 0.20%.

RESEARCH OBJECTIVE: Stress-rest myocardial perfusion scintigraphy has important prognostic ability to predict mortality, but can it also help predict just who will show the greatest benefit from PCI? Does MPS help forecast who will show an improved exercise capacity after PCI? In the UK, what is the prevalence of inducible ischemia in those patients who undergo a PCI procedure?

PATIENTS: Patients were mostly male (86%) and most (63%) but not all (37%) had stable angina. Patients were recruited prospectively from the a group of patients that had a positive diagnostic angiogram and were already scheduled to undergo an elective PCI procedure.

METHODS: Within one month before having their PCI procedure, patients in the study underwent stress-rest myocardial perfusion scintigraphy using a same day, single-isotope protocol using Tc-99m tetrofosmin. Treadmill exercise was utilized for the stress test as much as possible. The patient’s New York Heart Association functional status was assessed, and all patients answered the Seattle Angina Questionnaire. The cardiologists that performed the PCI procedures were blinded as to the outcome of the stress-rest perfusion scan. None of the PCI procedures were canceled due to the results of the perfusion scan.

At the 6 month follow-up visit after their PCI procedure, patients were once again evaluated for symptoms and functional status. A repeat treadmill test using the same protocol was performed in those patients that underwent treadmill stress ECG testing at baseline. Clinicians who performed this follow-up stress test were unaware of the results of the baseline test.

Scan images were evaluated quantitatively using the Cedars-Sinai AutoSPECT and AutoQuant programs. Semiquantitative analysis was performed using summed scoring with a 17 segment 5-point scale. There were two readers who looked at each patient study. The mean of the semiquantitative summed scores assigned by these two readers were used for statistical analysis.

RESULTS: There were a total of 123 patients evaluated. Of these, the exercise treadmill stress test was positive in 72% of patients. A reversible defect affecting greater than 10% of the myocardium was present in 20% of the patients, and smaller perfusion defects seen in an additional 54% of patients. The other 26% of patients did not have any reversible perfusion defects. The majority of patients had daily, stable angina.

Six months later at the follow-up evaluation, improvement was seen in the Seattle Angina Questionnaire and in exercise capacity. Looking at the entire patient population, the Seattle Angina Questionnaire physical limitation score improved from 66 to 75, which was highly statistically significant. Exercise capacity also showed a highly significant improvement, with the average exercise tolerance increasing from 7 to 9 METS. The New York Heart Association functional class, however, was unchanged in 62%, improved in 33%, and worse in 5%.

The predictors of clinical and functional improvement were also evaluated. A multivariate analysis found that independent, statistically significant predictors of improvement were male gender, limiting chest pain on stress testing, and inducible hypoperfusion on myocardial perfusion imaging.

CONCLUSION: Only 20% of patients undergoing percutaneous coronary intervention had inducible myocardial ischemia of 10% or greater. The combination of limiting chest pain with treadmill stress testing and significant reversible perfusion defects on perfusion scintigraphy help predict a large gain in improvement after revascularization.

SOURCE ARTICLE: J Nucl Cardiol. 2009 Jul 9. [Epub ahead of print]. Does myocardial perfusion scintigraphy predict improvement in symptoms and exercise capacity following successful elective percutaneous coronary intervention? Al-Housni MB, Hutchings F, Dalby M, Dubowitz M, Grocott-Mason R, Ilsley CD, Mason M, Mitchell AG, Kelion AD. Department of Cardiology, Royal Brompton and Harefield NHS Foundation Trust, Harefield Hospital, Harefield, Middlesex, United Kingdom. Medline Abstract.

Related posts

• Vinegar To Burn Fat (0)
• Is Laser Hair Removal Permanent? (0)
• Unclean AC Ducts Can Damage Your Health (0)
• Six Ways Unclean Air Ducts Promote Sickness (0)
• Six Reasons Your Air Ducts Could be Causing Serious Illness (0)