Author + information
- Faizel Osman, MB, BCh, MRCP* (, )
- Amer Chit, MB, MRCP and
- Peter E. Glennon, MD, MRCP
- ↵*Cardiology Department, Walsgrave Hospital, Clifford Bridge Road, Coventry CV2 2DX, United Kingdom
We note with great interest the findings of the recent MERLIN trial (1). We congratulate the investigators on their attempts to evaluate prospectively the efficacy of rescue angioplasty in this randomized controlled trial. We would, however, like to point out a few potential confounding factors that may have had an important effect on the findings.
We note that the definition used for failed lysis was “a second ECG [electrocardiogram] at 60 min after onset of lytic therapy, showing failure of the ST-segment elevation in the worst lead to have resolved by 50%, as compared with the pre-treatment ECG, as well as the presence of an accelerated idioventricular rhythm at the time of the 60-min ECG.” We believe this definition of failed lysis may have clearly influenced the outcome of the trial. As acknowledged in the accompanying editorial (2), the time of 60 min may have led to more patients being taken for coronary angiography than if 90 min were used. It is possible that a number of patients who were in the failed lysis category may in fact have had successful lysis if 90 min had been used. Clearly, this would have influenced the outcome measures used in the MERLIN trial, as those patients who were randomized to percutaneous coronary intervention (PCI) for failed lysis at 60 min may not have been taken to the catheterization laboratory if a 90-min ECG had shown resolution. At our institution we evaluate whether failed lysis has occurred at 90 min post-lytic therapy, allowing more time for lysis therapy to take effect; this may reduce not only the number of patients taken to the catheterization laboratory but also the number of patients exposed to a procedure with a definite risk.
The other important issue was the absence of any mention of ongoing chest pain. When assessing the possibility of failed lysis we, at our institution, always assess whether the patient has ongoing chest pain. This forms an important part of the evaluation of whether a patient is taken for angiography in the first place. Continual chest pain is regarded as a very good indicator of failed lysis and recommended as an important noninvasive marker for defining failed lysis (3). Some of the patients in the MERLIN trial who were entirely pain free may have undergone angiography; these patients might have been exposed to a procedure with a risk involved and hence affected the outcome parameters assessed.
We acknowledge the lack of large randomized trials in this field, and once again congratulate the investigators on their attempt to answer this important question. We hope further studies in this area will add to the emerging evidence regarding rescue angioplasty.
- American College of Cardiology Foundation
- Sutton A.G.C.,
- Campbell P.G.,
- Graham R.,
- et al.
- Grines CL, O'Neill WW. Rescue angioplasty. Does the concept need to be rescued?
- ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1999 Guidelines for the Management of Patients With Acute Myocardial Infarction)