Purpose: We conducted a prospective study to compare short- and long-term clinical outcomes between primary percutaneous coronary intervention (PPCI) and conservative strategies in patients with acute inferior ST segment elevation myocardial infarction (STEMI) with and without right ventricular (RV) involvement.
Methods: The study population involved 596 consecutive patients with primary acute inferior STEMI (mean age 57.3 y.o., males 85.9%) admitted to the hospital within 12 hours after the onset of symptoms. Based on treatment type, all patients were categorized into two groups: PPCI (+) who underwent PPCI (n=162) and PPCI (-) who did not undergo PPCI and received only standard medical treatment (n=434). Depending of RV involvement, each of above groups were further divided into two subgroups: those with RV myocardial infarction (RVMI(+)) and without it (RVMI(-)). Thus, within PPCI (+) group, 66 patients belong to RVMI(+) and the remaining 96 - RVMI(-), and within PPCI (-) group 192 patients belong to RVMI(+) and the remaining 242 - RVMI(-). We compared in-hospital and 1-year post-infarction cardiac mortality risks between PPCI (+) and PPCI (-) groups and their subgroups in terms of odds ratios (OR) adjusted to standard confounders (age, sex, diabetes, hypertension etc.).
Results: Both in-hospital and 1 year post-hospital mortality rates were significantly lower in PPCI (+) group than in PPCI (-) group (1.2% vs. 8.8%; OR 9.3; p<0.003 and 3.1% vs. 12.3%; OR 4.3; p<0.003 correspondingly). Regarding between-subgroup distribution of in-hospital and 1 year post-hospital cardiac death cases within each of above groups, we found significant differences of both rates between RVMI(-) and RVMI(+) subgroups of PPCI(-) group with higher in-hospital mortality rates in RVMI(+) subgroup (5.4% vs. 13.0%; OR 7.1; p<0.01) yet higher 1 year post-hospital mortality rates in RVMI(-) subgroup (15.5% vs. 7.9%; OR 3.9; p<0.01). Contrary to above, no significant differences were found between RVMI(-) and RVMI(+) subgroups of PPCI (+) group neither for in-hospital (0.0% vs. 3.0%; p>0.9) nor for 1 year post-hospital mortality risks (4.2% vs. 1.6%; p>0.4).
Conclusion: PPCI is associated with clinical benefits in preventing both in-hospital and 1-year post-hospital cardiac deaths in patients with primary acute inferior STEMI regardless of RV involvement. However, RVMI discloses its prognostic influence only for patients who receive only conservative treatment without PPCI.