Initial Q waves accompanying ST-segment elevation at presentation of acute myocardial infarction and 30-day mortality in patients given streptokinase therapy: an analysis from HERO-2

The prognostic significance of Q waves and T wave inversions in the ECG of patients with STEMI: A substudy of the TOTAL trial

BACKGROUND

The prognostic significance of Q waves and T-wave inversions (TWI) combined and separately in STEMI patients undergoing primary PCI has not been well established in previous studies.

METHODS

We included 7,831 patients from the TOTAL trial and divided the patients into categories based on Q waves and TWIs in the presenting ECG. The primary outcome was a composite of cardiovascular death, recurrent myocardial infarction (MI), cardiogenic shock or new or worsening NYHA class IV heart failure within one year. The study evaluated the effect of Q waves and TWI on the risk of primary outcome and all-cause death, and whether patient benefit of aspiration thrombectomy differed between the ECG categories.

RESULTS

Patients with Q+TWI+ (Q wave and TWI) pattern had higher risk of primary outcome compared to patients with Q-TWI- pattern [33 (10.5%) vs. 221 (4.2%); adjusted hazard ratio (aHR) 2.10; 95% CI, 1.45-3.04; p<0.001] within 40-days' period. When analyzed separately, patients with Q waves had a higher risk for the primary outcome compared to patients with no Q waves in the first 40 days [aHR 1.80; 95% CI, 1.48-2.19; p<0.001] but there was no additive risk after 40 days. Patients with TWI had a higher risk for primary outcome only after 40 days when compared to patients with no TWI [aHR 1.63; 95% CI, 1.04-2.55; p=0.033]. There was a trend towards a benefit of thrombectomy in patients with the Q+TWI+ pattern.

CONCLUSIONS

Q waves and TWI combined (Q+TWI+ pattern) in the presenting ECG is associated with unfavourable outcome within 40-days. Q waves tend to affect short-term outcome, while TWI has more effect on long-term outcome.

Prognostic value of initial QRS analysis in anterior STEMI: Correlation with left ventricular systolic dysfunction, serum biomarkers, and cardiac outcomes

BACKGROUND

The presence of pathologic Q waves on admission electrocardiogram (ECG) in patients with anterior ST-elevated myocardial infarction (STEMI) has been related to adverse cardiac outcomes. Our study evaluates the prognostic value of QRS complex and Q waves in patients with STEMI undergoing percutaneous coronary intervention.

METHODS

We prospectively analyzed the specific characteristics of QRS complex and pathologic Q waves on admission and on discharge ECG in 144 patients hospitalized for anterior STEMI. We correlated these findings with the development of left ventricular systolic dysfunction (LVSD), appearance of heart failure (HF) or death during follow-up, and levels of several biomarkers obtained 6 months after the index event.

RESULTS

Multivariate logistic regression analysis showed that QRS width (odds ratios [OR] 1.05, p = .001) on admission ECG and the sum of Q-wave depth (OR 1.06, p = .002) on discharge ECG were independent predictors of LVSD development. Moreover, QRS width on admission ECG was related to an increased risk of HF or death (OR 1.03, p = .026). Regarding biomarkers, QRS width on admission ECG revealed a statistically significant relationship with the levels of NT-pro-BNP at 6 months (0.29, p = .004); the sum of Q-wave depth (0.27, p = .012) and width (0.25, p = .021) on admission ECG was related to the higher levels of hs-cTnI; the sum of the voltages in precordial leads both on admission ECG (-0.26, p = .011) and discharge ECG (0.24, p = .046) was related to the lower levels of parathormone.

CONCLUSIONS

Assessment of QRS complex width and pathologic Q waves on admission and discharge ECGs aids in predicting long-term prognosis in patients with STEMI.

The high-risk ECG pattern of ST-elevation myocardial infarction: A substudy of the randomized trial of primary PCI with or without routine manual thrombectomy (TOTAL trial)

BACKGROUND

Useful tools for risk assessment in patients with STEMI are needed. We evaluated the prognostic impact of the evolving myocardial infarction (EMI) and the preinfarction syndrome (PIS) ECG patterns and determined their correlation with angiographic findings and treatment strategy.

METHODS

This substudy of the randomized Trial of Routine Aspiration Thrombectomy with PCI versus PCI Alone in Patients with STEMI (TOTAL) included 7860 patients with STEMI and either the EMI or the PIS ECG pattern. The primary outcome was a composite of death from cardiovascular causes, recurrent MI, cardiogenic shock, or New York Heart Association (NYHA) class IV heart failure within one year.

RESULTS

The primary outcome occurred in 271 of 2618 patients (10.4%) in the EMI group vs. 322 of 5242 patients (6.1%) in the PIS group [AdjustedHR, 1.54; 95% CI, 1.30 to 1.82; p < .001]. The primary outcome occurred in the thrombectomy and PCI alone groups in 131 of 1306 (10.0%) and 140 of 1312 (10.7%) patients with EMI [HR 0.94; 95% CI, 0.74-1.19] and 162 of 2633 (6.2%) and 160 of 2609 (6.1%) patients with PIS [HR 1.00; 95% CI, 0.81-1.25], respectively (p_interaction = 0.679).

CONCLUSIONS

Patients with the EMI ECG pattern proved to have an increased rate of the primary outcome within one year compared to the PIS pattern. Routine manual thrombectomy did not reduce the risk of primary outcome within the different dynamic ECG patterns. The PIS/EMI dynamic ECG classification could help to triage patients in case of simultaneous STEMI patients with immediate need for pPCI.

Early Q-wave morphology in prediction of reperfusion success in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention - A cardiac magnetic resonance imaging study

BACKGROUND

Pathological Q-wave (QW) in the electrocardiogram (ECG) before primary percutaneous coronary intervention (primary PCI) is a strong prognostic marker in patients with ST-segment elevation myocardial infarction (STEMI). However, current binary QW criteria are either not clinically applicable or have a lack of diagnostic performance. Accordingly, we evaluated the association between duration, depth and area of QW and markers of the effect of reperfusion (reperfusion success).

METHODS

A total of 516 patients with their first STEMI had obtained an ECG before primary PCI and an acute cardiac magnetic resonance imaging (CMR) at day 1 (interquartile range [IQR], 1-1) and at follow-up at day 92 (IQR, 89-96). The largest measurable QW in ECG was used for analysis of duration, depth and area of QW (QW morphology). The QW morphology was evaluated as a continuous variable in linear regression models and as a variable divided in four equally large groups.

RESULTS

The QW morphology as four equally large groups was significantly associated with all CMR endpoints (p ≤ 0.001) and showed a linear relationship (p ≤ 0.001) with final infarct size (for QW duration, β = 0.47; QW depth, β = 0.41 and QW area, β = 0.39), final infarct transmurality (for QW duration, β = 0.36; QW depth, β = 0.26 and QW area, β = 0.23) and final myocardial salvage index (for QW duration, β = -0.34; QW depth, β = -0.26 and QW area, β = -0.24).

CONCLUSION

Although modest, the QW morphology in STEMI patients showed significant linear association with markers of reperfusion success. Hence, it is suggested that the term pathological is not used as a dichotomous parameter in patients with STEMI but rather evaluated on the basis of extent.

Regression of Q waves and clinical outcomes following primary PCI in anterior STEMI

BACKGROUND

Pathological Q waves are correlated with infarct size, and Q-wave regression is associated with left ventricular ejection fraction improvement. There are limited data regarding the association of Q-wave regression and clinical outcomes. Our main objective was to assess the association of pathological Q wave evolution after reperfusion with clinical outcomes after anterior STEMI.

METHODS

Standard 12-lead electrocardiograms (ECGs) were recorded in 780 anterior STEMI patients treated with primary percutaneous coronary intervention (PCI) from the CIRCUS trial. ECGs were recorded before and 90 min following PCI, as well as at hospitalization discharge and 12 months of follow-up. The number of classic ECG criteria Q waves was scored for each ECG. Patients were classified in the Q wave regression group if they had regression of at least one Q wave between the post-PCI, the discharge and/or one year ECGs. Patients were classified in the Q wave persistent group if they had the same number or greater between the post-PCI, the discharge and/or 1 and one year ECGs. All-cause death and heart failure events were assessed for all patients at one year.

RESULTS

There were 323(43%) patients with persistent Q waves (PQ group), 378(49%) patients with Q wave regression (RQ group) and 60(8%) patients with non-Q wave MI (NQ group). Infarct size as measured by the peak creatine kinase was significantly greater in the PQ group compared to the RQ and NQ groups (4633 ± 2784 IU/l vs. 3814 ± 2595 IU/l vs. 1733 ± 1583 IU/l respectively, p < 0.0001). At one year, there were 22 deaths (7%) in the PQ-group, 15 (4%) in the RQ-group and none in the NQ-group (p = 0.04). There was a 4-fold increase in the risk of death or heart failure in the PQ compared to the NQ group (HR 4.7 [1.1; 19.3]; p = 0.03), but there was no significant difference between NQ and RQ groups (HR 3.3 [0.8; 13.8]; p = 0.09).

CONCLUSION

In a population of anterior STEMI patients, persistent Q waves defined according to the classic ECG criteria after reperfusion was associated with a 4-fold increase in the risk of heart failure or death compared to non-Q-wave MI, while Q-wave regression was associated with significantly lower risk of events.

ECG analysis in patients with acute coronary syndrome undergoing invasive management: rationale and design of the electrocardiography sub-study of the MATRIX trial

BACKGROUND

The twelve‑lead electrocardiogram (ECG) has become an essential tool for the diagnosis, risk stratification, and management of patients with acute coronary syndromes (ACS). However, several areas of residual controversies or gaps in evidence exist. Among them, P-wave abnormalities identifying atrial ischemia/infarction are largely neglected in clinical practice, and their diagnostic and prognostic implications remain elusive; the value of ECG to identify the culprit lesion has been investigated, but validated criteria indicating the presence of coronary occlusion in patients without ST-elevation are lacking; finally, which criteria among the multiple proposed, better define pathological Q-waves or success of revascularisation deserve further investigations.

METHODS

The Minimizing Adverse hemorrhagic events via TRansradial access site and systemic Implementation of AngioX (MATRIX) trial was designed to test the impact of bleeding avoidance strategies on ischemic and bleeding outcomes across the whole spectrum of patients with ACS receiving invasive management. The ECG-MATRIX is a pre-specified sub-study of the MATRIX programme which aims at analyzing the clinical value of ECG metrics in 4516 ACS patients (with and without ST-segment elevation in 2212 and 2304 cases, respectively) with matched pre and post-treatment ECGs.

CONCLUSIONS

This study represents a unique opportunity to further investigate the role of ECGs in the diagnosis and risk stratification of ACS patients with or without ST-segment deviation, as well as to assess whether the radial approach and bivalirudin may affect post-treatment ECG metrics and patterns in a large contemporary ACS population.

Lower plasma protein C activity is associated with early myocardial necrosis and no-reflow phenomenon in patients with ST elevation myocardial infarction

Background: Activity of protein C has important role in the development of early necrosis and no-reflow phenomenon in patients with ST-segment elevation myocardial infarction (STEMI) after successful primary percutaneous coronary intervention (pPCI). Methods: We examined association between plasma activity of protein C, antithrombin, coagulation factors II, VII, VIII and fibrinogen to early formation of new Q-waves (myocardial necrosis) before pPCI and early ST-segment resolution (microcirculatory reperfusion) after pPCI in patients with acute STEMI. According to ischaemic time, patients were considered as early or late presenters. 12-lead ECG was analysed for the presence of new Q-wave at admission and for significant ST-segment resolution 60 minutes after primary PCI. Results: In early presenters' group, protein C activity was significantly lower in patients who did not achieve significant ST-segment resolution after pPCI compared to patients who did (1.11 IU/L vs. 0.99 IU/L, p = .006) and in patients who had new Q-waves compared to group who had not (1.04 UI/l vs. 1.11 IU/L, p = .038). There was significant negative correlation between protein C activity and maximal CK-MB levels (R² = 0.06, p = .009) and BNP levels (R² = 0.109, p = .003) and significant positive correlation between protein C activity with LVEF (R² = 0.065, constant = 33.940, b = 11.968, p = .007) in early STEMI presenters. There were no differences between the activity of other examined haemostasis factors. Conclusion: Therefore we concluded that STEMI patients with early myocardial necrosis and no-reflow phenomenon after pPCI have lower activity of plasma protein C levels.

Comparison of the prognostic role of Q waves and inverted T waves in the presenting ECG of STEMI patients

BACKGROUND

Both Q waves and T-wave inversion (TWI) in the presenting ECG are associated with a progressed stage of myocardial infarction, possibly with less potential for myocardial salvage with reperfusion therapy. Combining the diagnostic information from the Q- and T-wave analyses could improve the prognostic work-up in ST-elevation myocardial infarction (STEMI) patients.

METHODS

We sought to determine the prognostic impact of Q waves and TWI in the admission ECG on patient outcome in STEMI. We formed four groups according to the presence of Q waves and/or TWI (Q+TWI+; Q-TWI+; Q+TWI-; Q-TWI-). We studied 627 all-comers with STEMI derived from two patient cohorts.

RESULTS

The patients with Q+TWI+ had the highest and those with Q-TWI- the lowest 30-day and one-year mortality. One-year mortality was similar between Q-TWI+ and Q+TWI-. The survival analysis showed higher early mortality in Q+TWI- but the higher late mortality in Q-TWI+ compensated for the difference at 1 year. The highest peak troponin level was found in the patients with Q+TWI-.

CONCLUSION

Q waves and TWI predict adverse outcome, especially if both ECG features are present. Q waves and TWI predict similar one-year mortality. Extending the ECG analysis in STEMI patients to include both Q waves and TWI improves risk stratification.

In the transition from fibrinolysis to primary PCI, the HERO trials help refine STEMI ECG interpretation and Q wave analysis potentially alters future management

Electrocardiogram sub-studies from the Hirulog Early Reperfusion/Occlusion 1 and 2 trials, which tested bivalirudin as an adjunctive anticoagulant to fibrinolysis in ST-elevation myocardial infarction, have contributed to the literature. The concept of using the presence of infarct lead Q waves to determine reperfusion benefit has subsequently been explored in multiple primary percutaneous coronary intervention studies. The angiographic findings before percutaneous coronary intervention combine with the baseline electrocardiogram to accurately diagnose ST-elevation myocardial infarction and evaluate its potential territory. This review discusses the relative merits of the presence of infarct lead Q waves versus time duration from symptom onset using observational data from cohorts of patients from multiple clinical trials. The presence of infarct lead Q waves at presentation has been repeatedly shown to be superior to time duration from symptom onset in determining prognosis, despite that continuous variable (time duration) statistically should be more powerful than dichotomous variable (Q wave). If quantitative or semi-quantitative measurement of Q waves correlates well with irreversible myocardial injury in vivo (a research goal of many cardiac magnetic resonance imaging studies), Q waves measurements by mirroring ST-elevation myocardial infarction evolution better than the current metric of time duration of symptoms will impact future ST-elevation myocardial infarction reperfusion management. Newer methodology will more quickly capture and transmit electrocardiogram information including infarct lead Q waves potentially before first medical contact, and help differentiate new evolving Q waves of the ongoing ST-elevation myocardial infarction from old changes. Q waves as the new metric in ST-elevation myocardial infarction reperfusion should be tested in upcoming trials.

QRS Score at Presentation Electrocardiogram Is Correlated With Infarct Size and Mortality in ST-Segment Elevation Myocardial Infarction Patients Undergoing Primary Percutaneous Coronary Intervention

BACKGROUND

In ST-segment elevation myocardial infarction (STEMI), QRS score at presentation ECG may reflect the progression of infarction and facilitate prediction of the degree of myocardial salvage achieved by reperfusion therapy.Methods and Results:Admission electrocardiogram (ECG) was studied in 2,607 patients with STEMI undergoing primary percutaneous coronary intervention (PCI) within 24 h of symptom onset. Patients were classified into 3 groups according to QRS score: low (0-3, n=1,227), intermediate (4-7, n=810), and high (≥8, n=570). An increase of infarct size estimated by median peak creatine phosphokinase was observed as QRS score increased (low score, 1,836 IU/L; inter-quartile range (IQR), 979-3,190 IU/L; intermediate score, 2,488 IU/L; IQR, 1,126-4,640 IU/L; high score, 3,454 IU/L; IQR, 1,759-5,639 IU/L; P<0.001). Higher QRS score was associated with higher long-term mortality (low, intermediate, and high score, 15.6%, 19.7%, and 23.7% at 5 years, respectively; log-rank P<0.001). The positive relationship of QRS score with mortality was consistently seen when stratified by infarct location. The association of high QRS score with increased mortality was most remarkably seen in patients with early (≤2 h) presentation (low, intermediate, and high score: 16.7%, 16.6%, and 28.1% at 5 years, respectively; log-rank P<0.001).

CONCLUSIONS

Higher QRS score at presentation ECG was associated with larger infarct size, and higher long-term mortality in patients with STEMI undergoing primary PCI. QRS score appears to be important in the early risk stratification for STEMI.

Prognostic implications of Q waves at presentation in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: An analysis of the HORIZONS-AMI study

BACKGROUND

Presence of Q waves on the presenting electrocardiogram (ECG) in patients with ST-segment elevation myocardial infarction (STEMI) has been associated with worse prognosis; however, whether the prognostic value of Q waves is influenced by baseline characteristics and/or rapidity of revascularization based on the guideline-based metric of door-to-balloon time remains unknown.

HYPOTHESIS

We hypothesized that Q waves in the presenting ECG will be predictive of long term mortality regardless of time to reperfusion.

METHODS

The Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial enrolled 3602 patients with STEMI undergoing primary percutaneous coronary intervention. We stratified patients without prior history of myocardial infarction or coronary revascularization according to presence or absence of pathological Q waves on their presenting ECG. Associations between Q waves, death, and cardiovascular outcomes within 3 years were assessed using Cox proportional hazards regression.

RESULTS

Among 2723 patients with evaluable ECGs, 1084 (39.8%) had Q waves on their presenting ECG. Male sex and time from symptom onset to balloon inflation were independent predictors of presence of Q waves. Patients with Q waves had higher adjusted risks of all-cause death (adjusted hazard ratio: 1.45, 95% confidence interval: 1.02-2.05, P = 0.04) and cardiac death (adjusted hazard ratio: 1.72, 95% confidence interval: 1.08-2.72, P = 0.02). The association between Q waves and cardiac death was consistent regardless of sex, diabetes status, target vessel, or door-to-balloon time (P_interaction > 0.4 for all).

CONCLUSIONS

Presence of Q waves on the presenting ECG in patients undergoing primary percutaneous coronary intervention due to STEMI is an independent predictor of mortality and adds prognostic value, regardless of sex or rapidity of revascularization.

Association Between Early Q Waves and Reperfusion Success in Patients With ST-Segment–Elevation Myocardial Infarction Treated With Primary Percutaneous Coronary Intervention

Background—

Pathological early Q waves (QW) are associated with adverse outcomes in patients with ST-segment–elevation myocardial infarction (STEMI). Primary percutaneous coronary intervention (PCI) may therefore be less beneficial in patients with QW than in patients without QW. Myocardial salvage index and microvascular obstruction (MVO) are markers for reperfusion success. Thus, to clarify the benefit from primary PCI in STEMI patients with QW, we examined the association between baseline QW and myocardial salvage index and MVO in STEMI patients treated with primary PCI.

Methods and Results—

The ECG was assessed before primary PCI for the presence of QW (early) in 515 STEMI patients. The patients underwent a cardiac magnetic resonance imaging scan at day 1 (interquartile range [IQR], 1–1) and again at day 92 (IQR, 89–96). Early QW was observed in 108 (21%) patients and was related to smaller final myocardial salvage index (0.59 [IQR, 0.39–0.69] versus 0.65 [IQR, 0.46–0.84]; P <0.001) and larger MVO (1.4 [IQR, 0.0–5.4] versus 0.0 [IQR, 0.0–2.4]; P <0.001) compared with non-QW. QW remained associated with both final myocardial salvage index (β=−0.12; P =0.03) and MVO (β=0.18; P =0.001) after adjusting for potential confounders.

Conclusions—

Patients presenting with their first STEMI and early QW in the ECG had smaller myocardial salvage index and more extensive MVO than non-QW despite treatment within 12 hours after symptom onset. However, final myocardial salvage index in patients with QW was substantial, and patients with QW still benefit from primary PCI.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01435408.

Simplifying electrocardiographic assessment in STEMI reperfusion management: Pros and cons

Current guidelines on STEMI reperfusion management do not incorporate further electrocardiographic details over the presence of significant ST elevation. Fibrinolysis is considered an alternative therapy to primary PCI if there is a long PCI-related delay, but the 2 therapies should not be combined. Meanwhile, reperfusion for ischemic stroke has evolved on mechanistic understanding - reperfusion benefit being greatest in the patient with small "core" infarct and large ischemic "penumbra". Fibrinolysis is not regarded as an alternative to mechanical thrombectomy, and the 2 therapies can be combined. In this article describing how reperfusion regimes have evolved along different paths for STEMI and for ischemic stroke, a new concept is made that in STEMI infarct lead Q waves can be the counterpart of the "core" and ST elevation the "penumbra". Suggestions to modify STEMI treatment algorithms are made, exploring further the relative role of (pre-hospital) fibrinolysis versus PCI particularly in younger patients presenting at the onset of their STEMI (no Q waves). In contrast, some patients particularly the older ones with more evolved STEMI (large Q waves present) may be much more suited for PCI despite expecting a long delay. The article finishes by describing potential future alterations in the method of reperfusion. Despite primary PCI being the well-established therapy, there are rooms for further research to optimize STEMI outcomes.

Effect of preinfarction angina pectoris on long-term survival in patients with ST-segment elevation myocardial infarction who underwent primary percutaneous coronary intervention

The influence of preinfarction angina pectoris (AP) on long-term clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI) remains controversial. In 5,429 patients with acute myocardial infarction (AMI) enrolled in the Coronary Revascularization Demonstrating Outcome Study in Kyoto AMI Registry, the present study population consisted of 3,476 patients with STEMI who underwent primary PCI within 24 hours of symptom onset and in whom the data on preinfarction AP were available. Preinfarction AP defined as AP occurring within 48 hours of hospital arrival was present in 675 patients (19.4%). Patients with preinfarction AP was younger and more often had anterior AMI and longer total ischemic time, whereas they less often had history of heart failure, atrial fibrillation, and shock presentation. The infarct size estimated by peak creatinine phosphokinase was significantly smaller in patients with than in patients without preinfarction AP (median [interquartile range] 2,141 [965 to 3,867] IU/L vs 2,462 [1,257 to 4,495] IU/L, p <0.001). The cumulative 5-year incidence of death was significantly lower in patients with preinfarction AP (12.4% vs 20.7%, p <0.001) with median follow-up interval of 1,845 days. After adjusting for confounders, preinfarction AP was independently associated with a lower risk for death (hazard ratio 0.69, 95% confidence interval 0.54 to 0.86, p = 0.001). The lower risk for 5-year mortality in patients with preinfarction AP was consistently observed across subgroups stratified by total ischemic time, initial Thrombolysis In Myocardial Infarction flow grade, hemodynamic status, infarct location, and diabetes mellitus. In conclusion, preinfarction AP was independently associated with lower 5-year mortality in patients with STEMI who underwent primary PCI.

Clinical impact of Q-wave presence on electrocardiogram at presentation of patients with ST-segment elevation myocardial infarction undergoing primary coronary intervention

This study evaluated the clinical impact of Q-wave presence on ECG at presentation of patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).From April 2005 to September 2009, 184 consecutive STEMI patients who underwent primary PCI within 12 hours of chest pain onset were retrospectively evaluated. Patients were grouped according to the presence (Q positive, n = 109) or absence (Q negative, n = 75) of Q waves on initial ECG at emergency room presentation. Major adverse cardiac events (MACE) and stent thrombosis (ST) were evaluated for 2 years. Risk factors for MACE and left ventricular (LV) remodeling by echocardiography were also evaluated.Baseline characteristics, including reperfusion time and infarct location, were similar between the groups. The MACE rate at 2 years was higher in the Q-positive group (32.1%) than in the Q-negative group (13.3%, P = 0.005). Independent risk factors for MACE were the presence of Q-wave (P = 0.008, Odds ratio 3.139) and no-reflow phenomenon (P = 0.016, Odds ratio, 2.819). LV remodeling was more frequent in the Q-positive group (47.9%) than in the Q-negative (24.5%, P = 0.009) group. Initial Q-wave presence (P = 0.048, Odds ratio 2.380) and anterior wall MI (P = 0.009, Odds ratio, 3.425) were independent risk factors for LV remodeling.The presence of Q waves in ECG of patients presenting with STEMI undergoing primary PCI provides an independent prognostic marker of clinical outcomes and left ventricular remodeling.

Prognostic implications of prominent R wave in electrocardiographic leads V1 or V2 in patients with acute coronary syndrome

Although the adverse prognosis of Q-waves on electrocardiogram (ECG) has been demonstrated, the prognostic significance of prominent R wave (PRW) in V1 or V2 across a broad spectrum of acute coronary syndrome (ACS) has not been specifically studied. In the Global Registry of Acute Coronary Events (GRACE) and the Canadian ACS Registry I ECG substudies, admission ECGs were analyzed in an independent core ECG laboratory. PRW was defined as R wave >40 to 50 ms in V1 or V2, R/S ≥1 in V1, or R/S ≥1.5 in V2. Among 11,895 patients with ACS, 495 (4.2%) had PRW; they were less likely to have a history of hypertension or heart failure and had lower GRACE risk scores, but a higher incidence of ST-segment depression (all p ≤0.001). Patients with PRW had similar rates of in-hospital death (2.8% vs 4.1%, respectively, p = 0.15) but lower rates of in-hospital heart failure (8.5% vs 15.2%, respectively, p = 0.02) and 6-month mortality (4.6% vs 8.4%, respectively, p = 0.004). In multivariable analyses, PRW was not a significant independent predictor of in-hospital mortality (adjusted odds ratio = 0.99, 95% confidence interval 0.55 to 1.8) or 6-month mortality (adjusted odds ratio = 0.70, 95% confidence interval 0.43 to 1.15). Among 4,418 patients who underwent coronary angiography, those with PRW had a higher prevalence of left circumflex artery disease (62.5% vs 49.5%, respectively, p = 0.01). In conclusion, across the broad spectrum of patients with ACS, PRW provides no significant additional prognostic utility beyond comprehensive risk assessment using the GRACE risk score. PRW is more frequently associated with left circumflex artery disease.

Reperfusion therapy for ST-segment elevation myocardial infarction: has ECG information been underutilized?

This perspective makes a contentious viewpoint that ECG information is underutilized in ST-segment elevation myocardial infarction (STEMI) and the next breakthrough rests on its full utilization. This is to better diagnose difficult cases such as ST changes during bundle branch block, posterior ST elevation and right-sided ST elevation during normal conduction, and aVR ST elevation. More importantly, this is to better characterize the STEMI for tailored reperfusion. The proposal is to develop a system capable of recording from multiple electrodes that one can apply onto oneself, and having analysis coordinated centrally via phone-internet transmission. This provides 'longitudinal' in addition to 'cross-sectional' ECG information. STEMI will be classified on a gray-scale according to its potential size and speed of Q wave evolution. The hypothesis is that large rapidly progressive STEMI is best treated by on-site fibrinolysis with prompt transferral to a percutaneous coronary intervention center; while small stuttering STEMI is best treated by primary percutaneous coronary intervention despite a long delay.

Clinical implications and correlates of Q waves in patients with ST-elevation myocardial infarction treated with fibrinolysis: observations from the CLARITY-TIMI 28 trial

BACKGROUND

The relationships between Q waves that appear during the acute phase of ST-elevation myocardial infarction (STEMI), clinical characteristics, ST-segment resolution (STRes), and clopidogrel therapy in patients treated with fibrinolysis are not well described.

HYPOTHESIS

We hypothesized that Q waves would be associated with less successful reperfusion and increased cardiovascular events.

METHODS

In the CLARITY-TIMI 28 trial, 3491 STEMI patients treated with fibrinolysis were randomized to clopidogrel or placebo. Electrocardiograms were evaluated for STRes post-fibrinolysis and the presence of pathologic Q waves during the index hospitalization in 3322 patients.

RESULTS

Q waves were identified in 2045 patients (61.6%) prior to discharge and were associated with increased odds of congestive heart failure (CHF) (adjusted odds ratio [ORadj ]: 2.10, P = 0.002) or the composite of cardiovascular death/CHF at 30 days (ORadj : 2.08, P ≤ 0.001). Q waves were associated with lower odds of Thrombolysis in Myocardial Infarction [TIMI] flow grade 2 to 3 (ORadj : 0.78, P = 0.028), TIMI myocardial perfusion grade 3 (ORadj : 0.83, P = 0.029), and complete STRes at 90 minutes (ORadj : 0.80, P = 0.030). Patients with both a Q wave and incomplete STRes 90 minutes after fibrinolysis were at higher risk for cardiovascular death or CHF (11.1%) than patients with no Q wave and at least partial STRes (1.9%). Overall, clopidogrel tended to be equally or more effective in patients without Q waves compared to those with Q waves.

CONCLUSIONS

Among STEMI patients treated with fibrinolysis, evaluating for Q waves prior to discharge is a simple method of assessing for less successful reperfusion and an increased risk of adverse 30-day cardiovascular outcomes. The combination of Q waves and 90-minute STRes allows additional risk refinement.

New ST-depression: an under-recognized high-risk category of 'complete' ST-resolution after reperfusion therapy

AIM

It is not known if there is an association between resolution of ST-elevation to ST-depression following fibrinolysis and 30-day mortality.

METHODS

In an ECG substudy of HERO-2, which compared bivalirudin to unfractionated heparin following streptokinase in 12,556 patients with ST-elevation myocardial infarction ECGs were recorded at baseline and at 60 minutes after commencing fibrinolysis. The main outcome measure was 30-day mortality.

RESULTS

Using summed ST-segment elevation and five categories of changes in the infarct leads, further ST-elevation, 0-30% ST-resolution, >30-70% (partial) ST-resolution, >70% (complete) ST-resolution, and new ST-depression occurred in 21.7, 24.9, 36.8, 14.8, and 1.8% of patients, with 30-day mortality of 12.3, 11.7, 8.0, 4.2, and 8.1%, respectively. For the comparison of new ST-depression with complete ST-resolution and no ST-depression, p<0.01 with 24-hour mortality 4.5 vs. 1.3%, respectively (p=0.0003). Patients with new ST-depression had similar peak cardiac enzyme elevations as patients with complete ST-resolution without ST-depression. On multivariate analysis including summed ST-elevation at baseline, age, sex, and infarct location, new ST-depression was a significant predictor of 30-day mortality (OR 1.82, 95% CI 1.42-4.29).

CONCLUSIONS

In patients with complete ST-resolution following fibrinolysis, new ST-depression at 60 minutes developed in 10.8% of patients. These patients had higher mortality than patients with complete ST-resolution without ST-depression and represent a high-risk group which could benefit from rapid triage to early angiography and revascularization as appropriate.

Relative prognostic value of baseline Q wave and time from symptom onset among men and women with ST-elevation myocardial infarction undergoing percutaneous coronary intervention

Q waves have been shown to be a stronger prognostic marker than time from symptom onset to percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction. We examined whether the relative importance of these 2 measurements is modulated by patient gender. Q waves in the area of ST-segment elevation on baseline electrocardiogram were evaluated at a central core laboratory in 4,530 patients with ST-segment elevation myocardial infarction (3,468 men and 1,062 women) without previous infarction and who underwent PCI in the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) trial. Women were older and had higher rates of diabetes, hypertension, Killip class >I, and lower creatinine clearance compared to men. Time from symptom onset to PCI >3 hours was associated with a trend toward worse 90-day mortality (adjusted hazard ratio 1.5, 95% confidence interval 0.9 to 2.2) in men but not in women (0.8, 0.5 to 1.4). In contrast, presence of Q waves on baseline electrocardiogram was associated with significantly higher 90-day mortality in men (adjusted hazard ratio 1.7, 95% confidence interval 1.0 to 2.7) and women (2.3, 1.2 to 4.2). In conclusion, in this gender-specific analysis, baseline Q wave was found be a better marker of risk of 90-day mortality than time from symptom onset to PCI, overall, and especially in women.

Contemporary pharmacological reperfusion in ST elevation myocardial infarction

PURPOSE OF REVIEW

Fibrinolysis remains a key therapeutic alternative mode of reperfusion in patients with ST segment elevation myocardial infarction (STEMI). Its venerability relates to the wealth of clinical efficacy evidence, ease of administration, and broad applicability to the large number of patients who cannot receive mechanical reperfusion within a reasonable period of time. This review focuses on recent data that will further enhance the clinician's ability to deliver a pharmacological reperfusion strategy to this patient population.

RECENT FINDINGS

Combined data from clinical trials as well as registry data support implementation of the guideline endorsed pharmacoinvasive strategy for patients unable to achieve rapid primary percutaneous coronary intervention. The most appropriate mode of reperfusion remains dependent upon the time from symptom onset to presentation as well as perceived delay to initiation of mechanical reperfusion therapy, and one strategy does not fit all patients at all times. Additional information is required in the growing population of elderly patients with STEMI to identify the most appropriate approach to reperfusion in this high-risk population.

SUMMARY

Despite extensive investigation concerning the optimal management of STEMI over the last three decades, significant knowledge gaps exist and the efficient application of current evidence to clinical practice remains elusive.

Baseline Q waves as a prognostic modulator in patients with ST-segment elevation: insights from the PLATO trial

BACKGROUND

Baseline Q waves may provide additional value compared with time from the onset of symptoms in predicting outcomes for patients with ST-segment elevation. We evaluated whether baseline Q waves superseded time from symptom onset as a prognostic marker of one-year mortality in patients with ST-segment elevation acute coronary syndrome. Our study was derived from data from patients undergoing primary percutaneous coronary intervention within 24 hours in the PLATelet inhibition and patient Outcomes trial

METHODS

Q waves on the baseline electrocardiogram were evaluated by a blinded core laboratory. We assessed the associations between baseline Q waves and time from symptom onset to percutaneous coronary intervention with peak biomarkers, ST-segment resolution on the discharge electrocardiogram, and one-year all-cause and vascular mortality.

RESULTS

Of 4341 patients with ST-segment elevation, 46% had baseline Q waves. Compared to those without Q waves, those with baseline Q waves were older, more frequently male, had higher heart rates, more advanced Killip class and had a longer time between the onset of symptoms and percutaneous coronary intervention. They also had higher one-year all-cause mortality than patients without baseline Q waves (baseline Q waves: 4.9%; no baseline Q waves: 2.8%; hazard ratio [HR] 1.78, 95% confidence interval [CI] 1.29-2.45, p < 0.001). Complete ST-segment resolution was greatest and all-cause mortality lowest among those with symptom onset three hours or less before percutaneous coronary intervention and no baseline Q waves. After multivariable adjustment, baseline Q waves, but not time from symptom onset, were associated with a significant increase in all-cause mortality (adjusted HR 1.42, 95% CI 1.10-2.01, p = 0.046) and vascular mortality (adjusted HR 1.58, 95% CI 1.09-2.28, p = 0.02).

INTERPRETATION

The presence of baseline Q waves provides useful additional prognostic insight into the clinical outcome of patients with ST-segment elevation. Clinical Trials.gov registration no. NCT00391872.

The prognostic meaning of the full spectrum of aVR ST-segment changes in acute myocardial infarction

AIMS

ST-elevation in lead aVR is known to be associated with a worse prognosis in patients with acute ST elevation myocardial infarction (MI) but the significance of ST depression in lead aVR has been unclear. Infarction of the inferior apex of the left ventricle may not be appreciated on the standard 12-lead electrocardiogram (ECG) except by observing ST depression in lead aVR which is reciprocal to lead V(7). We therefore determined the prognostic value of the full spectrum of aVR ST changes in patients presenting with acute ST elevation MI.

METHODS AND RESULTS

Lead aVR ST level was measured on randomization and 60 min ECGs in 15 315 patients with normal conduction from the HERO-2 trial. The outcome measure was 30-day mortality. aVR ST elevation ≥1 mm was associated with higher 30-day mortality for both inferior (22.5% for ≥1.5 mm and 13.2% for 1 mm) and anterior (23.5% for ≥1.5 mm and 11.5% for 1 mm) infarction. In contrast, deeper aVR ST depression (0, 0.5, 1, and ≥1.5 mm) was associated with higher mortality for anterior infarction (9.8, 13.2, 12.8, and 16.8%, respectively, trend P-value <0.0001) but not for inferior infarction. The resolution of aVR ST depression and ST elevation 60 min after fibrinolysis was associated with lower mortality.

CONCLUSION

There is a U-shaped relationship between 30-day mortality and aVR ST level in patients presenting with anterior but not inferior ST elevation MI.

High QRS score on admission strongly predicts impaired myocardial reperfusion in patients with a first anterior acute myocardial infarction

BACKGROUND

In patients with acute myocardial infarction (AMI), QRS score at presentation electrocardiogram (ECG) may reflect the evolutionary stage of the infarction and allow one to predict the degree of myocardial reperfusion potentially achievable by reperfusion therapy.

METHODS AND RESULTS

The relationship between QRS score on admission ECG and myocardial blush grade, an angiographic marker of myocardial reperfusion, was examined in 416 patients with a first anterior AMI who received reperfusion therapy within 6h after symptom onset. Patients were classified into 3 groups according to QRS score: 0 or 1 (n=102), 2-4 (n=228), and ≥5 (n=86). Higher QRS scores were associated with a longer time to admission, a greater ST-segment elevation, a higher frequency of impaired initial and final culprit coronary vessel flow, a higher peak creatine kinase level, and a higher frequency of impaired myocardial reperfusion as defined by myocardial blush grade 0/1 on the final angiogram. Multivariate analysis showed that a high QRS score ≥5 was the strongest predictor of impaired myocardial reperfusion (odds ratio 20.3, P<0.001). These findings were similar when the data were stratified according to time to admission (≤2h, >2h).

CONCLUSIONS

In patients with a first anterior AMI treated by reperfusion therapy, admission high QRS score ≥5 strongly predicts impaired myocardial reperfusion, even when presentation is early (≤2h).

Does silent myocardial infarction add prognostic value in ST-elevation myocardial infarction patients without a history of prior myocardial infarction? Insights from the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) Trial

BACKGROUND

ST-elevation myocardial infarction (STEMI) patients with a prior MI history have worse outcomes. The prognostic significance of silent MI (pathologic Q waves outside the ST-elevation territory) in STEMI is unclear.

METHODS

A total of 5,733 STEMI patients from 296 clinical centers in 17 countries were classified as (1) silent MI-baseline Q waves outside the infarct-related artery territory and no history of prior MI, (2) history of prior MI (HxMI), or (3) no prior MI.

RESULTS

Of 5,733 STEMI patients, 419 (7.3%) had silent MI, 693 (12.1%) had HxMI, and 4,621 (80.6%) had no prior MI. Ninety-day death and death/congestive heart failure/shock were higher in patients with HxMI (8.4% and 15.3%, respectively) and silent MI (6.7% and 13.9%, respectively) compared with patients with no prior MI (4.0% and 9.1%, respectively) (P ≤ .001 for all). After baseline adjustment, patients with HxMI were at increased risk for 90-day death (adjusted hazard ratio [HR] 1.62, 95% CI 1.18-2.21), whereas both those with HxMI and those with silent MI had increased risk of 90-day death/congestive heart failure/shock compared with those with no prior MI (adjusted HR 1.54, 95% CI 1.23-1.93 and adjusted HR 1.46, 95% CI 1.10-1.93, respectively).

CONCLUSIONS

Seven percent of STEMI patients had a silent MI. They represent a novel subgroup at increased risk comparable to those with known prior MI. Hence, in future studies, acquiring baseline Q wave data outside the distribution of acute injury should broaden the prognostic insights from STEMI patients with a prior MI.

Prognostic value of lead V1 ST elevation during acute inferior myocardial infarction

BACKGROUND

Lead V(1) directly faces the right ventricle and may exhibit ST elevation during an acute inferior myocardial infarction when the right ventricle is also involved. Leads V(1) and V(3) indirectly face the posterolateral left ventricle, and ST depression ("mirror-image" ST elevation) in V(1) through V(3) may reflect concomitant posterolateral infarction. The prognostic significance of V(1) ST elevation during an acute inferior myocardial infarction may therefore be dependent on V(3) ST changes.

METHODS AND RESULTS

In 7967 patients with acute inferior myocardial infarction in the Hirulog and Early Reperfusion or Occlusion-2 (HERO-2) trial, V(1) ST levels were analyzed with adjustment for lead V(3) ST level for predicting 30-day mortality. V(1) ST elevation at baseline, analyzed as a continuous variable, was associated with higher mortality. Unadjusted, each 0.5-mm-step increase in ST level above the isoelectric level was associated with approximately 25% increase in 30-day mortality; this was true whether V(3) ST depression was present or not. The odds ratio for mortality was 1.21 (95% confidence interval, 1.07 to 1.37) after adjustment for inferolateral ST elevation and clinical factors and 1.24 (95% confidence interval, 1.09 to 1.40) if also adjusted for V(3) ST level. In contrast, lead V(1) ST depression was not associated with mortality after adjustment for V(3) ST level. V(1) ST elevation >or=1 mm, analyzed dichotomously in all patients, was associated with higher mortality. The odds ratio was 1.28 (95% confidence interval, 1.01 to 1.61) unadjusted, 1.51 (95% confidence interval, 1.19 to 1.92) adjusted for V(3) ST level, and 1.35 (95% confidence interval, 1.04 to 1.76) adjusted for ECG and clinical factors. Persistence of V(1) ST elevation >or=1 mm 60 minutes after fibrinolysis was associated with higher mortality (10.8% versus 5.5%, P=0.001).

CONCLUSIONS

V(1) ST elevation identifies patients with acute inferior myocardial infarction who are at higher risk.

aVR ST elevation: an important but neglected sign in ST elevation acute myocardial infarction

AIM

This study evaluated the prognostic implications of aVR ST elevation during ST elevation acute myocardial infarction (AMI).

METHODS AND RESULTS

The Hirulog and Early Reperfusion/Occlusion-2 study randomized 17 073 patients with acute ST elevation AMI within 6 h of symptom onset to receive either bivalirudin or heparin, in addition to streptokinase and aspirin. The treatments had no effect on the primary endpoint of 30-day mortality. Electrocardiographic recordings were performed at randomization and at 60 min after commencing streptokinase. aVR ST elevation > or =1 mm was associated with higher 30-day mortality in 15 315 patients with normal intraventricular conduction regardless of AMI location (14.7% vs. 11.2% for anterior AMI, P = 0.0045 and 16.0% vs. 6.4% for inferior AMI, P < 0.0001). After adjusting for summed ST elevation and ST depression in other leads, associations with higher mortality were found with aVR ST elevation of > or =1.5 mm for anterior [odds ratio 1.69 (95% CI 1.16 to 2.45)] and of > or =1 mm for inferior AMI [odds ratio 2.41 (95% CI 1.76 to 3.30)]. There was a significant interaction between aVR ST elevation and infarct location. Thirty-day mortality was similar with anterior and inferior AMI when aVR ST elevation was present (11.5% vs. 13.2%, respectively, P = 0.51 with 1 mm and 23.5% vs. 22.5% respectively, P = 0.84 with > or = 1.5 mm ST elevation). After fibrinolytic therapy, resolution of ST elevation in aVR to <1 mm was associated with lower mortality, while new ST elevation > or =1 mm was associated with higher mortality.

CONCLUSION

aVR ST elevation is an important adverse prognostic sign in AMI.

Prognostic impact of Q waves on presentation and ST resolution in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention

Q waves can develop early in infarction and indicate infarct progression better than symptom duration. ST resolution (STR) is a predictor of reperfusion success. Our aim was to assess the prognostic impact of Q waves on presentation and STR after primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction. The combined end point was of mortality and adverse cardiovascular events (MACE; death, repeat myocardial infarction, or heart failure). Q waves on presentation (Q wave, n = 332; no Q wave, n = 337) was associated with significantly less mean STR, greater incidence of akinetic, dyskinetic, or aneurysmal regional wall motion, lower left ventricular ejection fraction, and worse in-hospital and 1-year MACEs (1 year 24% vs 8.2%, p <0.001). In addition, Q waves on presentation compared to no Q waves were associated with worse 1-year MACE regardless of infarct presentation in < or =3 hours, infarct location, and adequate STR (> or =70%). Q waves on presentation and inadequate STR (<70%), but not symptom duration, were independent predictors of MACE by multivariable analysis (adjusted hazard ratios of 2.7 and 2.4 for Q waves and STR, respectively). Compared to group A (no Q waves on presentation with STR), patients in group B (no Q waves with inadequate STR), group C (Q waves with STR), and group D (Q waves with inadequate STR) had hazard ratios of 3.0, 3.6, and 7.7, respectively (p <0.05) for the occurrence of MACE. In conclusion, assessment of Q-wave status on presentation and STR immediately after PPCI provides a simple and early clinical predictor of outcomes in ST-elevation myocardial infarction.

Predictors and implications of Q-waves in ST-elevation acute coronary syndromes

BACKGROUND

Q-waves in ST-elevation acute coronary syndromes carry adverse implications. We sought to determine the frequency, predictors, and implications of Q-waves in the current era that includes primary percutaneous coronary interventions.

METHODS

There were 14,916 patients evaluated in a multicenter observational study. They presented with ST-elevation acute coronary syndromes between 1999 and 2006. Clinical variables were compared between patients with versus without presenting Q-waves, with an additional comparison in the latter group between those with versus without subsequent development of Q-waves.

RESULTS

ST-elevation myocardial infarction occurred in 88.6% of patients. Q-waves were present on the initial electrocardiogram in 3929 patients and developed later in an additional 3085 patients. The incidence of Q-waves at presentation or during hospitalization decreased from 61% to 39% between 1999 and 2006 (linear trend P<.001). Both presenting and subsequent Q-waves were associated with greater likelihood of coronary occlusions and higher cardiac marker elevations (P <.001). Multivariate analysis showed that presenting Q-waves were associated with male sex (odds ratio [OR] 1.28), increased age (OR 1.06 per 5 years), diabetes (OR 1.26), smoking (OR 1.11), chronic aspirin (OR 0.79), acute aspirin (OR 0.87), other chronic cardiac medications (OR 0.80), prior heart failure (OR 0.67), and prior coronary artery disease (OR 0.61). Presenting Q-waves were independently associated with increased in-hospital mortality (OR 1.46), but Q-waves at presentation or during hospitalization did not impact 6-month mortality.

CONCLUSIONS

Q-waves in ST-elevation acute coronary syndromes are decreasing in incidence. Q-waves are a major determinant of in-hospital mortality, and targeted interventions should be directed to these high-risk patients.

Risk Stratification of Patients With Acute Anterior Myocardial Infarction and Right Bundle-Branch Block

BACKGROUND

Patients with an acute anterior ST-segment elevation myocardial infarction and right bundle-branch block (RBBB) have a high mortality risk, which may be stratified by early ECG changes.

METHODS AND RESULTS

In the Hirulog Early Reperfusion Occlusion (HERO-2) trial, 17 073 patients with acute myocardial infarction (AMI) within 6 hours of symptom onset were treated with streptokinase and randomized to receive bivalirudin or heparin. There was no difference in the primary end point of 30-day mortality. ECGs were recorded at randomization and 60 minutes after fibrinolytic therapy was begun. The 30-day mortality rate was 31.6% in the 415 patients with RBBB and anterior AMI at randomization and 33% in the 100 patients who developed new RBBB at 60 minutes from normal baseline conduction accompanying an anterior AMI. An increase in QRS duration by 20-ms increments was associated with increasing 30-day mortality rate in both RBBB groups on multivariable analyses with covariates of age, Killip class, systolic blood pressure, pulse, and prior infarction. Patients with QRS duration > or = 160 ms had higher 30-day mortality rate than those with QRS duration < 160 ms (37.2% versus 27.2%, P = 0.03, and 46.2% versus 24.5%, P = 0.025, in the 2 groups, respectively). For the patients with RBBB and anterior MI at randomization, RBBB resolved at 60 minutes in 40 patients, but 30-day mortality rate was unchanged. For those with persisting RBBB at 60 minutes, 30-day mortality rate was lower if ST-segment elevation had resolved by > or = 50% (20.4% versus 35.3%, P = 0.006).

CONCLUSIONS

In patients with anterior AMI and RBBB, increasing QRS duration is associated with increasing 30-day mortality. Early ST-segment resolution after fibrinolytic therapy despite persisting RBBB is associated with lower mortality rate.