This Article Abstract Figures Only Full Text (PDF) View Related Interventions with a King on CVN Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Glaser, R. Articles by Wilensky, R. L. Search for Related Content PubMed Articles by Glaser, R. Articles by Wilensky, R. L. Related Collections Related Article

Factors Associated With Poorer Prognosis for Patients Undergoing Primary Percutaneous Coronary Intervention During Off-Hours

Biology or Systems Failure?

Ruchira Glaser, MD^_*,_*, Srihari S. Naidu, MD, Faith Selzer, PhD, Alice K. Jacobs, MD, Warren K. Laskey, MD^||, Vankeepuram S. Srinivas, MD^¶, James N. Slater, MD^#, Robert L. Wilensky, MD^_**

^_* Cardiology Consultants, Christiana Hospital, Newark, Delaware
Cardiovascular Division, Winthrop University Hospital, Mineola, New York
Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania
Cardiology Division, Boston University Medical Center, Boston, Massachusetts
^|| Cardiology Division, University of New Mexico, Albuquerque, New Mexico
^¶ Division of Cardiology, Montefiore Medical Center/Albert Einstein College of Medicine, New York, New York
^# Cardiology Division, New York University, New York, New York
^_** Division of Cardiovascular Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania

	Abstract

Top Abstract Methods Results Discussion Conclusions REFERENCES

 
Objectives: We sought to determine whether poorer outcomes in patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (MI) during off-hours are related to delays in treatment, circadian changes in biology, or differences in operator-related quality of care.

Background: Previous investigation has suggested that patients undergoing primary PCI during off-hours are more likely to have adverse cardiac events than routine-hours patients, but the reasons for this remain poorly defined.

Methods: Clinical, angiographic, and procedural characteristics were compared in consecutive patients (n = 685) undergoing primary PCI in the National Heart, Lung, and Blood Institute Dynamic Registry between 1997 and 2006 that were classified as occurring during routine-hours (07:00 to 18:59) or off-hours (19:00 to 06:59). The primary end points were in-hospital death, MI, and target vessel revascularization.

Results: Median time from symptom onset to PCI was similar (off-hours 3.4 h vs. routine-hours 3.3 h). Patients presenting in off-hours were more likely to present with cardiogenic shock and multivessel coronary artery disease but were equally likely to present with complete occlusion of the infarct-related artery. Procedural complications including dissection were more frequent in off-hours patients. In-hospital death, MI, and target vessel revascularization were significantly higher in off-hours patients (adjusted odds ratio [OR]: 2.66, p = 0.001), and differences in outcomes were worse even if the procedure was immediately successful (adjusted OR: 2.58, p = 0.005, adjusting for angiographic success). Patients undergoing PCI on weekends had better outcomes during the daytime than nighttime.

Conclusions: Patients undergoing primary PCI for acute MI during off-hours are at significantly higher risk for in-hospital death, MI, and target vessel revascularization. These findings appear related to both diurnal differences in presentation and lesion characteristics, as well as differences in procedural complication and success rates that extend beyond differences in symptom-to-balloon time.

Key Words: percutaneous coronary intervention • primary angioplasty • off-hours • myocardial infarction

Abbreviations and Acronyms   DTB = door-to-balloon   GWTG-CAD = Get with the Guidelines–Coronary Artery Disease   MI = myocardial infarction   PCI = percutaneous coronary intervention   STEMI = ST-segment elevation myocardial infarction   TVR = target vessel revascularization

It is possible that differences in efficacy of PCI during off-hours versus routine hours are also related either to biologic differences linked to circadian variation or other factors associated with nighttime care that extend beyond DTB times (14–21). However, the combination of differences in clinical, angiographic, procedural, and time-related characteristics has not been accounted for simultaneously when examining and comparing the impact of primary PCI during off-hours and routine-hours, in the myocardial infarction (MI) patient.

We hypothesized that differences in the rates of in-hospital death, recurrent MI, and repeat target vessel revascularization (TVR) in patients undergoing off-hours versus routine-hours primary PCI could be further explained by a combination of differences in care and biology. To evaluate circadian-related biologic differences, we sought to assess differences in clinical presentation, underlying clinical characteristics, and angiographic features of off-hours versus routine-hours patients undergoing primary PCI including the rates of Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 before PCI, presence of thrombus, location of infarct-related artery, and lesion complexity. To attempt to understand the contribution of care received, we sought to evaluate differences in procedural characteristics and procedural complications, as well as periprocedural medication use.

	Methods

Top Abstract Methods Results Discussion Conclusions REFERENCES

 
National Heart, Lung, and Blood Institute Dynamic Registry.   The National Heart, Lung, and Blood Institute Dynamic Registry has previously been described (22) and involves multicenter recruitment of patients undergoing PCI in 5 recruitment waves from July 1997 through February 1998 (n = 2,524), February through June 1999 (n = 2,105), October 2001 through March 2002 (n = 2,047), February through May 2004 (n = 2,112), and February through August 2006 (n = 2,158). Baseline clinical, demographic, and angiographic characteristics, as well as the incidence of death, MI, and the need for a coronary artery bypass graft or repeat revascularization during the hospitalization, were recorded. Patients were interviewed by telephone at 1 year to collect clinical data, including vital status and the type and date of cardiovascular-related events. Each center received approval from its Institutional Review Board, and data were compiled and analyzed at the University of Pittsburgh.

Definitions.   Primary PCI was defined as emergent PCI for the treatment of STEMI within 12 h of symptom onset. Patients undergoing PCI for new left bundle branch block as presentation of acute MI were included. Patients who were previously treated with fibrinolysis ("rescue" or "late" PCI patients) were excluded from the analysis. Patients were stratified by PCI start time, with the routine-hours PCI cohort defined as PCI from 07:00 to 18:59 and the off-hours PCI cohort defined as PCI from 19:00 to 06:59, regardless of the day of the week. A secondary analysis defined the off-hours period to include both: 1) 19:00 to 06:59 for weekdays; and 2) weekends regardless of time of day. This secondary analysis was performed to assess further the association between differences in care during times when personnel were not on-site and biologic differences in circadian rhythm. Angiographic success was defined as at least a 20% reduction in lesion severity and final stenosis of <50%. Myocardial infarction was defined as the presence of either electrocardiographic or biochemical evidence of myocardial necrosis. Myocardial infarction after PCI was defined as a new rise in cardiac enzyme and clinical change to indicate new MI.

Statistical methods.   Baseline clinical, angiographic, and procedural characteristics and in-hospital outcomes were compared between the 2 cohorts by chi-square or Fisher exact test for discrete data and by the Wilcoxon rank sum test for continuous variables. Cumulative event rates at 1-year were calculated by the Kaplan-Meier method and comparisons were made using the log-rank test statistic. The associations between off-hours status and individual or composite in-hospital and 1-year outcomes were evaluated in univariate and multivariable analyses using logistic or Cox proportional hazards approaches. With both logistic and Cox regression methodologies, models were adjusted for prespecified risk factors. One set of models included only clinical and demographic factors, a second set included angiographic characteristics, and the final models included a combination of all variables included in the first and second sets. Both TIMI flow grade and time as a dichotomous variable (i.e., >6 h) were included in the initial model and neither was independently associated with outcome, and as such were not included in the final model presented. Other important variables, such as diabetes mellitus, were also forced into the model but were not significant. They are included in the table for the reader's information, despite lack of statistical significance. Goodness of fit for logistic regression models was assessed using the Hosmer-Lemeshow method (p > 0.20 for all models, indicating good fit), and proportional hazards assumptions were evaluated and met. Other analyses including an analysis by wave to assess the impact of time, as well as adjustment for site, were performed, but did not significantly impact on the findings of the main analyses. Although results improved over time, differences between the 2 groups persisted.

Additional sensitivity analyses were performed to assess for potential misclassification of STEMI in Wave 1 of the registry. In this wave, the variable was coded as "acute MI" and "emergent." To assess whether non-STEMI patients could have been misclassified in this wave, analyses were repeated without Wave 1 data and, when compared with the primary analysis, there were no significant differences in characteristics and results.

	Results

Top Abstract Methods Results Discussion Conclusions REFERENCES

 
Of 10,948 patients enrolled in Waves 1 to 5 of the National Heart, Lung, and Blood Institute Dynamic Registry, 685 (6.3%) underwent primary PCI. The majority of interventions (n = 457, 66.7%) were performed during routine-hours, with the remainder performed during off-hours (n = 228). The peak prevalence of procedures was late morning (11:00) and mid-afternoon (15:00 to 16:00). The mean and median times from symptom onset to PCI were somewhat longer in the off-hours versus routine-hours patients (mean time of 4.6 ± 3.0 h vs. 4.3 ± 3.1 h; p = 0.09 [median: 3.4 h vs. 3.3 h]).

Patient and procedural characteristics.   Patients undergoing off-hours PCI were younger, more often men, and more often smokers compared with routine-hours patients undergoing PCI (Table 1). Off-hours patients had higher rates of cardiogenic shock compared with the rates of cardiogenic shock in routine-hours patients.

Medication use.   Procedural glycoprotein IIb/IIIa receptor inhibitor use (64.5% vs. 64.6%, p = 0.98) and heparin use (95.2% vs. 94.2%, p = 0.7) did not differ between off-hours and routine-hours patients, and aspirin use before the procedure was similar (82.9% vs. 87.7%, p = 0.08). Periprocedural thienopyridine use was lower in patients treated off-hours (48.2% vs. 58.2%, p = 0.01). At discharge, however, there was no difference (p > 0.10 for all) in the use of secondary prevention agents including angiotensin-converting enzyme inhibitors (63.5% vs. 59.5%), beta-blockers (86.3% vs. 87.0%), calcium channel blockers (10.0% vs. 8.0%), statins (71.1% vs. 68.2%), or aspirin (97.2% vs. 96.1%).

Clinical outcomes.   Off-hours patients had significantly higher rates of combined in-hospital death and recurrent MI, as well as combined death, MI, and repeat TVR rates (Table 3, Fig. 1). When examining individual outcomes by time quartile (Fig. 1), the main difference remained in a "diurnal" pattern, with similar event rates during both halves of the day and during both halves of the night. After adjusting for important differences in clinical and angiographic characteristics (as noted in Table 4), the risk of in-hospital death, recurrent MI, and TVR remained higher (adjusted odds ratio [OR]: 2.66) (Tables 3 and 4) in patients presenting during off-hours. Although initial differences in stent use and TIMI flow grade were present, these were not independently associated with outcome in multivariable analysis. Ejection fraction and lesion characteristics including thrombus presence were also examined but were not independently associated with outcome. The end point of TVR was examined in greater detail, and TVR via PCI occurred in 0.9% of routine-hours patients and 3.5% of off-hours patients, while TVR via coronary artery bypass grafting occurred in 2.0% of routine-hours patients and 4.9% of off-hours patients.

View larger version (25K): [in this window] [in a new window] [Download PPT slide]   Figure 1 Hospital Mortality, MI, and TVR by PCI Start Time Quartile Cumulative death, myocardial infarction (MI), and target vessel revascularization (TVR) by time of percutaneous coronary intervention (PCI). Overall and trend: p < 0.001.

Classification of off-hours.   To examine further the association between mortality and time of day versus immediate availability of medical resources, we examined death and MI, and death, MI, and TVR by both time and weekday and weekend (Fig. 2). In both weekdays and weekends, adverse outcomes were highest at night. In addition, rates of adverse outcomes were only slightly higher on weekends at either time than at night, and this was not statistically significant. Finally, adverse outcomes were only slightly higher during weekend days than weekday days, and this was not statistically significant.

View larger version (27K): [in this window] [in a new window] [Download PPT slide]   Figure 2 Adverse Hospital Outcomes by Time of PCI and Day of the Week Adverse outcomes by time of PCI and day of the week. Abbreviation as in Figure 1.

	Discussion

Top Abstract Methods Results Discussion Conclusions REFERENCES

Despite similar lesion characteristics, we found that lesions treated at night were more often accompanied by procedural complications including dissection. Procedural success was a significant factor in subsequent adverse outcomes, but even patients with successful procedures had a higher risk of adverse events during off-hours.

Our findings are consistent with the prior observation that higher angioplasty failure rates occur at night, though hitherto there has not been sufficient angiographic or procedural information to understand potential causes (15,23,24). In this respect, those complications that may be related to operator performance, such as vessel dissection, were more frequent at night, whereas complications potentially related to lesion characteristics, such as distal embolization, were not. The use of time-consuming devices was also less frequent at night than during daytime hours, despite similar lesion characteristics. It is possible that diurnal differences in lesion characteristics, such as lower than TIMI flow grade 3 in the infarct-related artery at the time of intervention during off-hours, and diurnal differences in clinical characteristics, such as higher rates of cardiogenic shock, additionally affected operator performance. Lower rates of preprocedural thienopyridine use during off-hours also may have contributed to higher procedural complications and reduced success.

When procedural success was not achieved, operators were more likely to state that the "lesion did not respond appropriately" during off-hours. We found no significant differences in characteristics indicative of lesion complexity associated with adverse events after PCI (25,26). However, flow characteristics before PCI were less favorable in off-hours patients, and rates of TIMI flow grade 3 were less often achieved after off-hours PCI. It is possible that circadian variations may be associated with differential outcomes after primary PCI. Notably, platelet aggregation is heightened during the morning hours (27,28). A prothrombotic state has been associated with treatment outcome after both fibrinolytic therapy and elective PCI, with resistance to fibrinolytic therapy observed in the early morning hours (29–31). Thus although it is possible that lack of procedural success was purely operator- or procedure-related, it is likely that in some cases biologic factors also contributed to the lower success rates of PCI during off-hours, as poorer flow was present prior to PCI.

Although delays in treatment time have been shown to be a factor in poorer outcomes during off-hours (6–11), in the present study, off-hour angioplasty was not associated with significant delay when using symptom onset to PCI time. Further, we found that the incidence of adverse events was only slightly higher on weekends, a time when delays would be expected to be greater than weekdays, with the majority of difference consistently occurring between nighttime versus daytime PCI, regardless of weekday or weekend. In addition, daytime outcomes were only slightly, and not statistically significantly, better during weekdays than weekends, suggesting that time delay was only 1 factor for subsequent adverse events.

Sicker patients may present during off-hours because of inability to wait for routine-hours. However, the converse has been postulated; namely, that waiting for routine-hours will increase the risk for those who wait, independent of their initial severity. It has also been postulated that off-hours patients are sicker because MI onset while sleeping may lead to longer ischemic times upon arrival. We found higher rates of cardiogenic shock and higher rates of multivessel coronary artery disease in those patients presenting during off-hours. In addition, TIMI flow grade 3 was less likely upon arrival to the catheterization laboratory, although the infarct-related artery was equally likely to be completely occluded in both groups. However, after accounting for these factors, off-hours presentation remained associated with poorer outcomes.

Unlike prior analyses, which mostly have been composed of very large registries, we were able to examine detailed clinical and angiographic features in MI patients (5,6,9,15). In this regard, although difficult to study all potential factors, we found few differences in a wide variety of characteristics, leaving the possibilities of circadian-related differences and operator performance. As mentioned previously, a role for circadian biologic differences may be suggested by less favorable flow upon angiography and after PCI and possibly by higher rates of multivessel coronary artery disease and cardiogenic shock. The possibility of operator fatigue also warrants careful consideration, as this is a potentially modifiable risk factor, and changes in public policy could mitigate its impact. For instance, there has been a recent strong emphasis on the need for public health measures aimed at improving quality of care in MI patients. Regionalization of MI care has been advocated by some to allow shorter DTB times and higher volume operators, both of which have been demonstrated to improve outcome (32,33). In a similar fashion, regional or high volume centers may be able to provide resources including more operators or less daytime duties in nighttime operators, which could reduce the impact of possible operator fatigue. If the presently proposed measures are implemented along with those that additionally address operator and staff fatigue, they may further enhance the benefits of primary PCI (33).

Finally, our findings suggesting that the potential hazard of off-hours PCI is not solely related to differences in DTB time are supported by a recent analysis of the Get with the Guidelines–Coronary Artery Disease (GWTG–CAD) database, where over 62,000 patients were examined and found to have similar mortality rates, despite longer DTB times in the off-hours group (34). Importantly, that analysis differed from the present study in that ours is exclusively a primary PCI cohort, whereas the GWTG–CAD database included 12% who received fibrinolysis, 34% who received no reperfusion therapy, and only 42% who had any revascularization. In addition, only 32% of patients in that study had STEMI. Nonetheless, the STEMI cohort in that analysis also had no significant difference in mortality by time of presentation, but even in this cohort, only 60% underwent cardiac catheterization, and only 70% underwent any revascularization, whereas in our study, all patients underwent primary PCI for STEMI. Finally, our study by definition includes centers that have the capacity to provide primary PCI, whereas the GWTG–CAD database looks at many different types of care centers, including some without primary PCI capability. The wide variety of care and severity of illness in the patients examined in that study may have contributed to lack of appreciable differences in overall mortality by time of presentation, even in STEMI patients. Interestingly, despite these differences, Jneid et al. (34), similarly conclude that "although...campaigns to reduce time to reperfusion are laudable, improvements in DTB times should be complemented by multifaceted approaches to optimize multiple levels of medical care in parallel."

Study limitations.   This analysis uses symptom onset to PCI time. The prognostic significance of symptom onset is not clear, as some prior analyses have suggested a lack of reliability, and others have found symptom onset to be more predictive of adverse events than DTB time (35,36). However, our evaluation of weekend PCI by time allows some understanding of the impact of a "closed" cardiac catheterization laboratory and the effects of its delays in DTB time. Weekend PCI analysis is a means of stratifying outcome, though separate multivariable adjustments were not made for this particular exploratory analysis. The number of control variables required in multivariate models is high given this event rate, leading to overfitted models. Finally, in this cohort study, it is possible that differences exist that are not fully controlled by the statistical methods.

	Conclusions

Top Abstract Methods Results Discussion Conclusions REFERENCES

 
The current study observed over 2.7-fold higher risk for in-hospital mortality, MI, and repeat TVR in patients treated with primary PCI during off-hours. Off-hours primary PCI was associated with lower angiographic success and higher complication rates and may suggest both biologic factors including poorer anterograde flow, as well as nighttime performance issues such as operator fatigue reduced use of adjunctive devices and lower preprocedural thienopyridine use as contributors to poorer outcome. As such, factors that extend beyond differences in DTB time may contribute to poorer outcomes in patients presenting with MI during off hours.

	Footnotes

 
Funded in part by a National Heart, Lung, and Blood Institute grant (HL33292-14).

^_* Reprint requests and correspondence: Dr. Ruchira Glaser, 252 Chapman Road, Newark, Delaware 19702 (Email: ruglaser{at}gmail.com).

Manuscript received April 17, 2008; revised manuscript received August 6, 2008, accepted August 18, 2008.

	REFERENCES

Top Abstract Methods Results Discussion Conclusions REFERENCES

 

1. Keeley EC, Hillis LD. Primary PCI for myocardial infarction with ST-segment elevation N Engl J Med 2007;356:47-54.[Free Full Text]
2. Grines CL, Browne KF, Marco J, et al. Primary Angioplasty in Myocardial Infarction Study Group A comparison of immediate angioplasty with thrombolytic therapy for acute myocardial infarction: the Primary Angioplasty in Myocardial Infarction Study Group N Engl J Med 1993;328:673-679.[Abstract/Free Full Text]
3. GUSTO IIb Substudy Investigators A clinical trial comparing primary coronary angioplasty with tissue plasminogen activator for acute myocardial infarction: the Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO IIb) Angioplasty Substudy Investigators N Engl J Med 1997;336:1621-1628.[Abstract/Free Full Text]
4. Keeley EC, Boura JA, Grines CL. Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomized trials Lancet 2003;361:13-20.[CrossRef][Web of Science][Medline]
5. Pinto DS, Kirtane AJ, Nallamothu BK, et al. Hospital delays in reperfusion for ST-elevation myocardial infarction: implications when selecting a reperfusion strategy Circulation 2006;114:2019-2025.[Abstract/Free Full Text]
6. Kostis WJ, Demissie K, Marcella SW, et al. Weekend versus weekday admission and mortality from myocardial infarction N Engl J Med 2007;356:1099-1109.[Abstract/Free Full Text]
7. McNamara RL, Wang Y, Herrin J, et al. NRMI Investigators Effect of door-to-balloon time on mortality in patients with ST-segment elevation myocardial infarction J Am Coll Cardiol 2006;47:2180-2186.[Abstract/Free Full Text]
8. Sadeghi HM, Grines CL, Chandra HR, et al. Magnitude and impact of treatment delays on weeknights and weekends in patients undergoing primary angioplasty for acute myocardial infarction (the CADILLAC Trial) Am J Cardiol 2004;94:637-640.[CrossRef][Web of Science][Medline]
9. De Luca G, Suryapranata H, Ottervanger JP, Antman EM. Time delay to treatment and mortality in primary angioplasty for acute myocardial infarction: every minute of delay counts Circulation 2004;109:1223-1225.[Abstract/Free Full Text]
10. Magid DJ, Wang Y, Herrin J, et al. Relationship between time of day, day of week, timeliness of reperfusion, and in-hospital mortality for patients with acute ST-segment elevation myocardial infarction JAMA 2005;294:803-812.[Abstract/Free Full Text]
11. Zahn R, Vogt A, Zeymer U, et al. Arbeitsgemeinschaft Leitender Kardiologischer Krankenhausarzte. In-hospital time to treatment of patients with acute ST elevation myocardial infarction treated with primary angioplasty: determinants and outcome. Results from the registry of percutaneous coronary interventions in acute myocardial infarction of the Arbeitsgemeinschaft Leitender Kardiologischer Krankenhausarzte. Heart 2005;91:1041-1046.[Abstract/Free Full Text]
12. Brodie BR, Hansen C, Stuckey TD, et al. Door-to-balloon time with primary percutaneous coronary intervention for acute myocardial infarction impacts late cardiac mortality in high-risk patients and patients presenting early after the onset of symptoms J Am Coll Cardiol 2006;47:289-295.[Abstract/Free Full Text]
13. Lauer MS. Primary angioplasty—time is of the essence JAMA 2000;283:2988-2989.[Free Full Text]
14. Bradley EH, Herrin J, Wang Y, et al. Strategies for reducing the door-to-balloon time in acute myocardial infarction N Engl J Med 2006;355:2308-2320.[Abstract/Free Full Text]
15. Spencer FA, Becker RC. Circadian variations in acute myocardial infarction: patients or health care delivery? J Am Coll Cardiol 2003;41:2143-2146.[Free Full Text]
16. Henriques JPS, Haasdijk AP, Zijlstra F. Outcome of primary angioplasty for acute myocardial infarction during routine duty hours versus during off-hours J Am Coll Cardiol 2003;41:2138-2142.[Abstract/Free Full Text]
17. Saleem MA, Kannam H, Aronow WS, et al. The effects of off-normal hours, age and gender for coronary angioplasty on hospital mortality in patients undergoing coronary angioplasty for acute myocardial infarction Am J Cardiol 2004;93:763-764.[CrossRef][Web of Science][Medline]
18. The MILIS Study Group Circadian variation in the frequency of onset of acute myocardial infarction N Engl J Med 1985;313:1315-1322.[Abstract]
19. Arntz HR, Willich SN, Schreiber C, et al. Diurnal, weekly and seasonal variation of sudden death. Population-based analysis of 24061 consecutive cases. Eur Heart J 2000;21:315-320.[Abstract/Free Full Text]
20. Cannon CP, McCabe CH, Stone PH, et al. TIMI III Registry and TIMI IIIB Investigators Circadian variation in the onset of unstable angina and non–Q-wave acute myocardial infarction Am J Cardiol 1997;79:253-258.[CrossRef][Web of Science][Medline]
21. Muller JE. Circadian variation and triggering of acute coronary events Am Heart J 1999;137:S1-S8.[CrossRef][Web of Science][Medline]
22. Williams DO, Holubkov R, Yeh W, et al. Percutaneous coronary intervention in the current era compared with 1985–1986: the National Heart, Lung, and Blood Institute registries Circulation 2000;102:2945-2951.[Abstract/Free Full Text]
23. Garot P, Juliard JM, Benamer H, Steg PG. Are the results of primary percutaneous transluminal coronary angioplasty for acute myocardial infarction different during the "off" hours? Am J Cardiol 1997;79:1527-1529.[CrossRef][Web of Science][Medline]
24. Zahn R, Schiele R, Seidl K, et al. MITRA Study Group Daytime and nighttime differences in patterns of performance of primary angioplasty in the treatment of patients with acute myocardial infarction. Maximal Individual Therapy in Acute Myocardial Infarction (MITRA) Study Group. Am Heart J 1999;138:1111-1117.[CrossRef][Web of Science][Medline]
25. Zaacks SM, Allen JE, Calvin JE, et al. Value of the American College of Cardiology/American Heart Association stenosis morphology classification for coronary interventions in the late 1990s Am J Cardiol 1998;82:43-49.[CrossRef][Web of Science][Medline]
26. Ryan TJ, Faxon DP, Gunnar RM, et al. ACC/AHA Task Force Guidelines for percutaneous transluminal coronary angioplasty. A report of the American College of Cardiology/American Heart Association Task Force on assessment of diagnostic and therapeutic cardiovascular procedures (subcommittee on percutaneous transluminal coronary angioplasty). Circulation 1988;78:486-502.[Free Full Text]
27. Tofler GH, Brezinski D, Schafer AI, et al. Concurrent morning increase in platelet aggregability and the risk of myocardial infarction and sudden cardiac death N Engl J Med 1987;316:1514-1518.[Abstract]
28. Petralito A, Gibiino S, Maino MF, et al. Daily modification of plasma fibrinogen, platelet aggregation, Howell's time, PTT, TT, and anti-thrombin III in normal subjects and in patients with vascular disease Chronobiologia 1982;9:195-201.[Web of Science][Medline]
29. Andreotti F, Davies GJ, Hackett DR, et al. Major circadian fluctuations in fibrinolytic factors and possible relevance to time of onset of myocardial infarction, sudden cardiac death and stroke Am J Cardiol 1988;62:635-637.[CrossRef][Web of Science][Medline]
30. Kono T, Morita H, Nishina T, et al. Circadian variations of onset of acute myocardial infarction and efficacy of thrombolytic therapy J Am Coll Cardiol 1996;27:774-778.[Abstract]
31. Temizhan A, Dincer I, Pamir G, Alpman A, Oral D. Is there any effect of chronobiological changes on coronary angioplasty? J Cardiovasc Risk 2001;8:15-19.[Medline]
32. Bates ER. Outcomes of angioplasty vs. thrombolysis by hospital angioplasty volume JAMA 2001;285:1701-1707.[Free Full Text]
33. Bradley EH, Roumanis SA, Radford MJ, et al. Achieving door-to-balloon times that meet quality guidelines: how do successful hospitals do it? J Am Coll Cardiol 2005;46:1236-1241.[Abstract/Free Full Text]
34. Jneid H, Fonarow GC, Cannon CP, et al. Impact of time of presentation on the care and outcomes of acute myocardial infarction Circulation 2008;117:1-8.[Free Full Text]
35. De Luca G, Suryapranata H, Zijlstra F, et al. ZWOLFE Myocardial Infarction Study Group Symptom-onset-to-balloon time and mortality in patients with acute myocardial infarction treated by primary angioplasty J Am Coll Cardiol 2003;42:991-997.[Abstract/Free Full Text]
36. Cannon CP, Gibson MC, Lambrew CT, et al. Relationship of symptom-onset-to-balloon time and door-to-balloon time with mortality in patients undergoing angioplasty for acute myocardial infarction JAMA 2000;283:2941-2947.[Abstract/Free Full Text]

This article has been cited by other articles:

				S. R. Dixon, C. L. Grines, and W. W. O'Neill The year in interventional cardiology. J. Am. Coll. Cardiol., June 2, 2009; 53(22): 2080 - 2097. [Full Text] [PDF]

				A. Dominguez-Rodriguez, F. Bosa-Ojeda, and P. Abreu-Gonzalez Cross-Talk Between Primary Percutaneous Coronary Intervention, Arterial Inflammation, and Light/Dark Patterns J. Am. Coll. Cardiol. Intv., April 1, 2009; 2(4): 368 - 368. [Full Text] [PDF]

				R. Glaser Reply J. Am. Coll. Cardiol. Intv., April 1, 2009; 2(4): 368 - 369. [Full Text] [PDF]

				A. P. Shah and W. J. French Physicians ... Wake Up! J. Am. Coll. Cardiol. Intv., December 1, 2008; 1(6): 689 - 691. [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) View Related Interventions with a King on CVN Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Glaser, R. Articles by Wilensky, R. L. Search for Related Content PubMed Articles by Glaser, R. Articles by Wilensky, R. L. Related Collections Related Article