Less than 30 Minutes of Door to Balloon Time can Completely Alter the Clinical Course of the Right Ventricular Myocardial Infarction

Abbreviations: IMI: Inferior Myocardial Infarction; RV: Right Ventricular; RVMI: Right Ventricular Myocardial Infarction; PPCI: Primary Percutaneous Coronary Intervention; RCA: Right Coronary Artery; ECG: Electrocardiography; LVESV: Left Ventricle End-Systolic Volume; LVEDV: Left Ventricle End-Diastolic Volume; LVEF: LV Ejection Fraction; RVDD: RV End-Diastolic Diameter; RVFAC: RV Fractional Area Change; TAPSE: Tricuspid Annular Plane Systolic Excursion; STEMI: ST Elevation Myocardial Infarction ARTICLE INFO abstract


Introduction
There is limited data on the association between right ventricular (RV) function and adverse events after acute right ventricular myocardial infarction (RVMI) [1]. Most of the information on RVMI is from the pre-mechanical revascularization era. RVMI increases the risk of hemodynamic instability, atrioventricular conduction block and increases in-hospital mortality in patients with inferior myocardial infarction (IMI) [2,3]. Significant improvement in the prognosis of RVMI was achieved after reperfusion treatments.
However, studies have demonstrated that RVMI is still associated with significant morbidity and mortality, even in the mechanical reperfusion era [4]. A shorter time taken to reperfusion of the occluded vessel contributes to the recovery of RV function. Early revascularization plays an important role in the recovery of RV function; conversely, late revascularization is associated with higher RV dysfunction and complications [5,6]. The purpose of the current study was to investigate the complication rates in patients with IMI with and without RVMI who were treated with early primary percutaneous coronary intervention (PPCI) successfully.

Patient Selection and Study Protocol
Consecutive patients, admitted with IMI due to proximal right coronary artery (RCA) occlusion and treated with successful PPCI, were included to the study. There was no critical stenosis in the other vessels Successful PPCI was defined with three criteria: a) TIMI 3 coronary flow (complete perfusion) after PPCI.

b) Resolution of ST segment elevation > 70% c)
Complete relief of chest pain.
If any of these three criteria was absent, the patient was ex-

Echocardiography
Images were obtained in the left lateral decubitus position using a commercially available system (Vivid 3 pro General Elec-  in such a way that the annulus moved along the M-mode cursor and the total displacement of the RV base from end-diastole to end-systole was measured [8].

Statistical Analysis
Continuous data were presented as mean standard deviation and categorical data were presented as frequencies and percentages. Differences in characteristics between patient groups were evaluated using the unpaired Student t test and chi-square test.
Pearson's chi-square test was used for non-qualitative data when the data were examined (Fisher's exact Chi-square test was used when the number of value (n) in boxes was below 5). Mann-Whitney U test was used for data not showing normal distribution and Student T test was used for data with normal distribution. The 95% confidence interval was determined and differences were considered significant at < 0.05.

Results
The study population consisted of 46 consecutive patients, admitted with IMI and treated with PPCI. 16  and hospital stay. A minor complication was observed in one patient with RVMI, this was not statistically significant (p > 0.05).
Atrial fibrillation was detected in one patient in IMI group and this was not statistically significant too (P> 0.05) ( Table 3).   Length of stay in ICCU was slightly higher in RVMI group but it was not statistically significant (p>0.05) ( Table 4). There was no statistically significant difference between two groups with respect to peak CK-MB levels (p> 0.05). When correlation analysis was performed between peak CK-MB values and length of hospital stay, no significant correlation was found between the length of ICCU / hospital stay and peak CK-MB values in patients with IMI (p> 0.05).
However, a significant positive correlation was found between the peak CK-MB values and both length of ICCU and hospital stay in patients with RVMI. (Hospital stay r: 0.668, p<0.001; ICCU stay r: 0.803, p<0.001). After an average of 10 months follow up of patients, no new infarction or mortality was observed in both groups.  [11,12]. Multiple studies also demonstrated that mortality rates improve by achieving decreased D2B times [13]. A review of a large cardiovascular registry (10,965 patients) found that the median D2B time was 96 minutes and only 44% of the patients were meeting the <90-minute national benchmark goal [14].
Cannon et al. showed that mortality increased by 41% for STEMI patients with D2B times over 120 minutes [10].
In our study, the mean D2B time was less than half an hour.
Furthermore, the median time from onset of chest pain to hospital arrival was less than 2.6 hours and the median time from onset of chest pain to PPCI was less than 3 hours. The low rate of mortality and morbidity in our study can be explained by early reperfusion therapy.  [2].
The presence of ST-segment elevation in lead V4R was one of the inclusion criteria for RVMI group in our study. We showed that ST-segment elevation in lead V4R was not an independent predictor of major complications and in-hospital mortality after early successful reperfusion treatment. Anavekar et al. and Zornoff et al. showed that RV function was weakly correlated with LV function and demonstrated that RV function quantified with RVFAC was independently associated with an increased risk of mortality and heart failure [20,21]. Antoni at al. showed that RVFAC and RV strain were independent predictors of the occurrence of the composite end points (all-cause mortality, reinfarction, and hospitalization for HF) [1]. Samad et al. showed that TAPSE predicted mortality independently, after adjustment for LVEF and age [22]. We found that RVFAC and TAPSE values were significantly lower and RV diameter was significantly higher in RVMI group. However, we showed that they were not predictors of mortality and morbidity when early and successful reperfusion performed. Gonzales et al. demonstrated that STEMI patients with TIMI risk classification 0-1, 2-3, and ≥4 has in-hospital mortality of 7%, 13% and 26%, respectively [23].
In our study, the mean TIMI risk score of the patients was 2.83 ± 1.0. However, after early reperfusion treatment there was no mortality in our study. We showed that clinical outcomes could be changed by early reperfusion therapy in patients with RVMI.
We found a significant correlation between peak CK-MB level and length of ICCU/ hospital stay in RVMI patients. In fact, there was no statistically significant difference with respect to peak CK-MB level between patients with and without RVMI. Furthermore, the peak CK-MB level was not associated with the development of complications and the length of hospital stay in patients without RVMI. However, the length of hospital stay was prolonged in patients complicated with RVMI who have higher peak CK-MB levels.
This was substantially related to increased length of ICCU stay. Increased length of ICCU stay was probably due to the clinician's concern about RVMI-related complications. Our study showed that the increase of peak CK-MB level was not associated with the development of complications when early and successful reperfusion was performed.

Limitations
The main limitation of our study was the small number of patients. Our results should be tested with more patients in largescale studies. The absence of the patients who have longer door to balloon times may be accepted as a limitation of the study, but the mean door to balloon time is short in our center.

Conclusion
We conclude that, there is no difference in mortality and morbidity between patients with pure IMI and patients complicated by RVMI, when early and successful reperfusion therapy was performed with a D2B time of less than 30 minutes.