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Letters
February 2, 2000

Primary Angioplasty vs Thrombolysis in Elderly Patients

Author Affiliations
 

Phil B.FontanarosaMD, Deputy EditorIndividualAuthorStephen J.LurieMD, PhD, Fishbein FellowIndividualAuthor

JAMA. 2000;283(5):601-602. doi:10.1001/jama.283.5.601

To the Editor: In their comparison of direct angioplasty and intravenous thrombolysis as reperfusion therapy for elderly patients with acute myocardial infarction, Dr Berger et al1 concluded that primary angioplasty is associated with modestly lower short- and long-term mortality. However, this conclusion is problematic because of the inherent limitations of data from the Cooperative Cardiovascular Project (CCP).

The study sample of patients who underwent angioplasty is not comparable to the sample of patients who received thrombolytic therapy in several vital respects. The CCP data do not permit an intention-to-treat analysis and thus are susceptible to selection and survival biases. The database cannot identify patients who died while awaiting primary angioplasty or patients in whom primary angioplasty was not attempted after cardiac catheterization—a group that comprises 10% to 19% of the primary-angioplasty groups in randomized trials2,3 and has a mortality as high as 14.1%,3 several times the mortality of patients who actually undergo primary angioplasty. The CCP database lacks angioplasty times for one quarter of patients who underwent angioplasty on the day of admission without antecedent thrombolysis, a group apparently excluded from the study, which thus used a potentially nonrandom sample of primary angioplasty patients.

In addition, electrocardiographic characteristics of the thrombolytic and angioplasty cohorts are significantly different. The thrombolytic cohort primarily consists of patients with electrocardiographic ST-segment elevation or left bundle-branch block in accord with standard clinical criteria, whereas the angioplasty cohort also includes patients without ST-segment elevation. Of the thrombolytic cohort, 68.0% had ST-segment elevation and 30.2% had new Q waves, compared with 61.6% and 23.5%, respectively, in the angioplasty cohort1 (P<.001 for each comparison). Patients in the CCP without ST-segment elevation have a substantially better prognosis, with 30-day mortality of 13.5%, compared with 17.2% for patients with ST-segment elevation.4 There are similarly large survival differences according to the presence of new Q waves.

Finally, the median interval between arrival at the hospital and angioplasty balloon inflation in the current study was 129 minutes compared with intervals of 76 to 78 minutes from randomization to balloon inflation in randomized trials,3 suggesting that community practice of primary angioplasty involves substantially greater delay than even the Global Use of Strategies to Open Occluded Arteries in Acute Coronary Syndromes (GUSTO-IIb) trial, the most inclusive trial. Subgroup analysis of the GUSTO-IIb trial showed markedly higher mortality among patients with randomization-to-inflation intervals of longer than 90 minutes,3 so the finding of benefit in the CCP despite such delays heightens concern about underlying bias.

These potential biases could substantially affect both crude and adjusted mortality estimates. Intention-to-treat analyses of comparable thrombolytic and primary angioplasty groups of elderly patients are still needed.

References
1.
Berger  AKSchulman  KAGersh  BJ  et al.  Primary coronary angioplasty vs thrombolysis for the management of acute myocardial infarction in elderly patients.  JAMA. 1999;282:341-348.Google Scholar
2.
Grines  CLBrowne  KFMarco  J  et al.  A comparison of immediate angioplasty with thrombolytic therapy for acute myocardial infarction.  N Engl J Med. 1993;328:673-679.Google Scholar
3.
Berger  PBEllis  SGHolmes  DR  et al.  Relationship between delay in performing direct coronary angioplasty and early clinical outcome in patients with acute myocardial infarction: results from the Global Use of Strategies to Open Occluded Arteries in Acute Coronary Syndromes (GUSTO-IIb) Trial.  Circulation. 1999;100:14-20.Google Scholar
4.
Thiemann  DRCoresh  JOetgen  WJPowe  NR The association between hospital volume and survival after acute myocardial infarction in elderly patients.  N Engl J Med. 1999;340:1640-1648.Google Scholar
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