Methods

This study is part of a wider protocol in progress to assess thrombotic and bleeding complications of cardiac procedures in western Finland. The present analysis is based on 414 patients on long-term warfarin treatment for atrial fibrillation and referred for PCI in 6 hospitals with a policy to perform PCI during uninterrupted OAC. Only patients who had an international normalized ratio (INR) at the therapeutic range (2.0 to 3.5) during PCI were included. Baseline and procedural data were provided by local institutional clinical registries, which prospectively collect information in computerized databases. Medical records of eligible patients were reviewed to determine periprocedural antithrombotic strategies and incidence of major bleeding or access site complications and MACCEs during hospitalization. We also gathered data on other hospital complications and length of hospitalization. The CHADS ₂ score for congestive heart failure, hypertension, age, diabetes, and stroke (2 times) quantifying annual stroke risk for patients who have nonvalvular atrial fibrillation was recorded for all patients.

Coronary angiography and PCI were performed using a radial or femoral approach for arterial access and hemostasis was obtained according to local practice. Lesions were treated according to contemporary interventional techniques. LMWH (enoxaparin sodium), unfractionated heparin, and glycoprotein IIb/IIIa inhibitors were administered entirely at the operator’s discretion.

The primary end points were in-hospital MACCEs and in-hospital bleeding complications. MACCEs were defined as the occurrence of any of the following after PCI: death, myocardial infarction, revascularization of target vessel (emergency or elective coronary artery bypass grafting or repeated PCI), stent thrombosis, or stroke. Bleeding complications were classified as major bleedings according to Thrombolysis In Myocardial Infarction criteria and access site complications. Stent thrombosis was defined according to Academic Research Consortium classification as definite and probable. Periprocedural myocardial infarction was not routinely screened, but if suspected, a troponin level >3 times the normal 99th percentile level was required for the diagnosis. For the diagnosis of myocardial reinfarction, a new increase >50% above the baseline injury marker level was required. Target vessel revascularization was defined as a reintervention driven by any lesion located in the stented vessel.

Vascular access site complications included pseudoaneurysm or arteriovenous fistula, occurrence of retroperitoneal hemorrhage, and need for corrective surgery. A decrease in blood hemoglobin level of >4.0 g/dl or need for transfusion of ≥2 U of red blood cells or prolongation of index hospitalization because of access site bleeding were also considered access site complications.

This study complied with the Declaration of Helsinki. Ethics committees of participating hospitals approved the study protocol. Written informed consent or a waiver of the requirement of written informed consent was obtained.

Continuous variables are presented as mean ± SD and categorical variables as count and percentage. Study groups were compared by chi-square, Fisher’s exact test, and Mann–Whitney test as appropriate. Because treatment groups differed in baseline and procedural variables, propensity score analysis was used to control for all known patient factors that might be related to the decision to perform PCI with or without additional heparins. The propensity score was calculated by logistic regression with backward selection by including important clinical and operative variables with a p value <0.20 in univariate analysis. Receiver operating characteristics curve analysis was used to estimate the area under the curve of the model, predicting the probability of being included in either group. The calculated propensity score was employed only for 1-to-1 matching and for adjustment of risk in the overall series. Stratification analysis by propensity score was not performed because of the limited number of patients included in this series. The 1-to-1 propensity score matching between study groups was performed according to a difference in the logit of a propensity score of <0.040 between each patient pair in the study group with or without additional AC. Such a caliber width was equal to 0.2 of the SD of the logit of the present calculated propensity score (0.2). Separate propensity scores were developed to assess study groups with and without prolonged LMWH. A 2-sided p value <0.05 was required for statistical significance. All data were analyzed using SPSS 17 for Mac (SPSS, Inc., Chicago, Illinois).

Results

Altogether 414 patients with atrial fibrillation and long-term OAC with warfarin undergoing PCI were identified. PCI was performed in 196 patients without any additional AC than therapeutic (INR 2.0 to 3.5) warfarin. In 218 patients an unfractionated heparin or LMWH bolus or subcutaneous LMWH therapy was used in addition to therapeutic OAC during the index procedure. Baseline clinical characteristics, indications for PCI, and procedural characteristics in these study groups are presented in Tables 1 and 2 . No differences in age, gender, or CHADS ₂ score were detected between groups. Patients with additional heparins were more frequently treated for acute coronary syndrome. Femoral access was used in most patients in the 2 groups with no difference in the use of closure devices.

Periprocedural antithrombotic therapies used during and after the index PCI are presented in Table 3 . After PCI, triple therapy with warfarin, aspirin, and clopidogrel was used more often in patients without than in those with additional heparins (74.6% vs 63.8%, p = 0.02).

Table 4 and Figure 1 present in-hospital rates of adverse events in the 2 groups. MACCEs occurred in 8 patients without (4.1%) and 7 patients with (3.2%) additional heparins. Major bleeding was infrequent and occurred in 2 patients without (1.0%) versus 8 patients with (3.7%, p = 0.11) additional heparins, respectively. Overall access site complications were less frequent in patients with no additional AC.

Table 4

Summary of outcome events at discharge

Variable	Overall Series			Propensity Score-Matched Pairs
	Additional AC		p Value	Additional AC		p Value
	No	Yes		No	Yes
	(n = 196)	(n = 218)		(n = 122)	(n = 122)
Major adverse cardiac and cerebrovascular events	8 (4.1%)	7 (3.2%)	0.79	6 (4.9%)	1 (0.8%)	0.12
Death	2 (1.0%)	4 (1.8%)	0.69	2 (1.6%)	1 (0.8%)	0.56
Myocardial infarction	3 (1.5%)	3 (1.4%)	1.00	1 (0.8%)	0	1.00
Target vessel revascularization	3 (1.5%)	1 (0.5%)	0.35	1 (0.8%)	0	1.00
Stent thrombosis	3 (1.5%)	1 (0.5%)	0.35	3 (2.5%)	0	0.08
Stroke	1 (0.5%)	0	0.47	1 (0.8%)	0	1.00
Thrombolysis In Myocardial Infarction major bleeding	2 (1.0%)	8 (3.7%)	0.11	1 (0.8%)	5 (4.1%)	0.21
Access site complications	10 (5.1%)	24 (11%)	0.032	7 (5.7%)	16 (13%)	0.049
Pseudoaneurysm	3 (1.5%)	8 (3.7%)	0.23	0	6 (4.9%)	0.013
Bleeding delaying discharge	3 (1.5%)	13 (6.0%)	0.022	3 (2.5%)	9 (7.4%)	0.14
Need for corrective surgery	1 (0.5%)	1 (0.5%)	1.00	1 (0.8%)	1 (0.8%)	1.00
Hemoglobin decrease >4 g/dl	1 (0.5%)	4 (1.8%)	0.38	0	3 (2.5%)	0.25
Blood transfusion	0	6 (2.8%)	0.031	0	5 (4.1%)	0.06

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