Baseline Characteristics
The baseline characteristics of the study population are presented in Table 1. The mean age of the population was 61 ± 11 years. Eighty per cent of the patients were male. The median follow-up was 2.9 years (range, 6 months to 15 years). Indications for IABP use were cardiogenic shock (68%), haemodynamic support during PCI (6%), high-risk CABG (17%), refractory or post-myocardial infarction angina (9%), valvular dysfunction or mechanical complications (8%), or refractory ventricular arrhythmias (1%). In some patients there was more than one indication for IABP support. Reperfusion therapy was performed in 84%. Forty per cent of the patients were treated with primary PCI, 25% with thrombolysis, 21% had a rescue PCI and 25% were treated with emergency CABG.
Table 1 Baseline and clinical characteristics of patients with AMI treated with IABP
Predictors of Successful IABP Weaning
Baseline characteristics of patients who survived until IABP removal (78%, n = 341) are presented in Table 2. IABP running time in this group was 1 day in 23%, 2–5 days in 57%, and ≥6 or more days in 20% of these patients. Patients with IABP running time ≥ 6 days had a significantly lower systolic blood pressure and were more often in cardiogenic shock. Prior AMI, prior CABG, diminished LVF, administration of inotropic or antiarrhythmic drugs (AAD) and need for resuscitation were also significantly more frequent in this subgroup as compared with an IABP running time of 2–5 days. They were also less frequently treated with primary PCI.
Table 2 Baseline and clinical characteristics of patients with AMI who survived until IABP removal, stratified by IABP running time
Thirty-Day and Long-term Outcome
Cumulative survival was 58%, 47%, and 30% at 1, 5, and 10 years follow-up, respectively. In the patient group who survived until IABP removal, cumulative survival was 75%, 61%, and 39% at 1, 5, and 10 years follow-up, respectively. Patients with IABP running time of ≥ 6 days had a significantly higher long-term mortality compared with patients with an IABP running time of 2–5 days (p < 0.05) (Fig. 1).
Adjusted predictors of 30-day mortality are presented in Table 3. Age (hazard ratio (HR) 1.03; 95% CI, 1.0–1.06), cardiogenic shock (HR, 2.7; 95% CI, 1.2–6.0), the need for inotropic agents (HR, 7.5; 95% CI, 2.8–19.6) and CPR (HR, 2.3; 95% CI, 1.2–4.2) were independently associated with lower 30-day survival. Independent predictors of higher 30-day survival were treatment with primary PCI (HR, 0.2; 95% CI, 0.1–0.5), thrombolysis (HR, 0.1; 95% CI, 0.0–0.8), rescue PCI (HR, 0.3; 95% CI, 0.1–0.6), and CABG (HR, 0.1; 95% CI, 0.0–0.3).
Table 3 Multivariate regression analysis
Adjusted predictors of long-term mortality in patients who survived until IABP removal are presented in Table 3. Prior CVA or transient ischaemic attack (TIA; HR, 1.8; 95% CI, 1.0–3.4), need for AAD (HR, 2.3; 95% CI, 1.5–3.3), and renal replacement therapy (HR, 2.3; 95% CI, 1.2–4.3) were independently associated with lower long-term survival. Independent predictors of higher long-term survival were primary PCI (HR, 0.6; 95% CI, 0.4–1.0), rescue PCI (HR, 0.5; 95% CI, 0.3–0.9), and CABG (HR, 0.3; 95% CI, 0.1–0.5).
IABP Use Over the Years
Between 1990 and 1994 (period I) 116 patients were treated with IABP: from 1995 to 1999 (period II) 141 patients and between 2000 and 2004 (period III) 180 patients. Mean age was 62 ± 9, 59 ± 12, 63 ± 11 years in period I, II and III respectively (p < 0.05). No difference in the number of patients in cardiogenic shock was observed. The use of primary PCI increased from 20% in period I to 58% in period III (p < 0.001). The use of thrombolytic therapy (p < 0.01) and emergency CABG (p < 0.01) decreased. The utilisation of reperfusion therapy increased over time (p < 0.01). Mean IABP running time decreased from three to two days between period I and III. The complication rate decreased from 28% to 9% (p < 0.001) Thirty-day mortality decreased from 41% to 26% (p < 0.05).
IABP-Related Complications
Complications were observed in 88 patients (20%). The most frequently observed complications were infection (n = 34; 8%), bleeding (n = 23; 5%), and limb ischaemia (n = 21; 5%). Of all bleeds, five patients had major bleeding. Limb ischaemia was transient in the majority of the cases (n = 17, 81%), with either spontaneous recovery, or after IABP removal. Vascular surgery was needed in four patients (19%).