Mouhieddin Traboulsi

Effect of coronary angioplasty on precordial QT dispersion

Dispersion of the QT interval is a measure of inhomogeneity of ventricular repolarization. Because ischemia is associated with regional abnormalities of conduction and repolarization, we hypothesized that the surface electrocardiographic interval dispersion would increase in patients with symptomatic coronary artery disease in the absence of myocardial infarction and that successful revascularization would reduce QT interval dispersion. Thirty-seven consecutive patients with ischemia due to 1-vessel coronary artery disease without prior myocardial infarction who underwent percutaneous transluminal coronary angioplasty (PTCA) were evaluated. Standard 12-lead electrocardiograms were performed 24 hours before, 24 hours after, and late (>2 months) after PTCA. Precordial QT interval dispersions were determined from differences in the maximum and minimum corrected QT intervals. Mean QT interval dispersion before PTCA was 60 +/- 9 ms, immediately after PTCA 23 +/- 14 ms (p <0.001), and late after PTCA 29 +/- 18 ms (p <0.001 vs before PTCA). The shortest precordial QT interval increased immediately after PTCA (367 +/- 40 vs 391 +/- 39 ms; p <0.02) and then remained stable late after PTCA (376 +/- 36 ms, p = NS vs immediately after PTCA). Symptomatic recurrent ischemia in 8 patients with documented restenosis increased QT interval dispersion (56 +/- 15 ms [p <0.01] vs 25 +/- 14 ms immediately after PTCA), which decreased again after successful repeat PTCA (22 +/- 13 ms [p <0.01] vs before the second PTCA). QT interval dispersion decreases after successful coronary artery revascularization and increases with restenosis. Therefore, QT interval dispersion may be a marker of recurrent ischemia due to restenosis after PTCA.

Expedited transfer for primary percutaneous coronary intervention: a program evaluation

Background: A shorter time from symptom onset to reperfusion is associated with improved outcomes for patients with ST-segment elevation myocardial infarction (MI). Primary percutaneous coronary intervention is a favourable method of reperfusion if performed effectively and expeditiously. We sought to evaluate the impact of an expedited pre-hospital diagnosis and transfer pathway developed by a multidisciplinary team on the door-to-balloon time in a large urban community. Methods: We included all patients with ST-segment elevation MI who presented within 12 hours after symptom onset and who sought medical attention through Emergency Medical Services within the boundaries of the city of Calgary in the 16 months following the introduction of the pathway in June 2004. The primary aim was to determine the proportion of patients who received percutaneous coronary intervention within the recommended door-to-balloon time of 90 minutes. Results: The 358 patients (268 men) in the study cohort had a mean age of 63.2 (standard deviation 12.7) years; 140 (39.1%) had an anterior MI; and 23 (6.4%) had cardiogenic shock. The introduction of the pathway resulted in a median door-to-balloon time of 62 (interquartile range 45–84) minutes. A door-to-balloon time within 60 minutes and within the currently recommended 90 minutes was achieved in 48.9% and 78.8% of the patients respectively. The in-hospital and 30-day mortality rates were both 3.1%. Interpretation: In a community with multiple regional hospitals and a single facility for percutaneous coronary intervention, the implementation of a multidisciplinary pre-hospital diagnosis and transfer pathway was feasible and resulted in most patients in the study cohort receiving primary percutaneous coronary intervention within the recommended door-to-balloon time of 90 minutes.

An Early Cardiac Access Clinic Significantly Improves Cardiac Rehabilitation Participation and Completion Rates in Low-Risk ST-Elevation Myocardial Infarction Patients

BACKGROUND Survivors of an acute ST-elevation myocardial infarction (STEMI) remain at high risk for future cardiac events. Cardiac rehabilitation (CR) participation significantly reduces coronary artery disease (CAD) morbidity and mortality risk. Regrettably, poor utilization of CR services post STEMI is common, accentuating a critical action gap in the trajectory of CAD management. The objective of this study was to determine whether integration of an early cardiac access clinic (ECAC), held within 4-14 days of hospital discharge, could improve CR utilization rates following an STEMI. METHODS Between January 2008 and July 2009, 245 consecutively admitted STEMI patients (19.6% female) deemed low risk following early re-establishment of coronary blood flow, were assigned to the ECAC model. An historic comparison group (n=224) was identified based on all STEMI patient admissions at the same tertiary care facility during the 2007 calendar year that met ECAC eligibility criteria. The primary outcomes were rates of CR referral, orientation attendance, program participation, and completion. RESULTS The ECAC cohort had significantly higher rates of CR referral (100% vs 55.8%, P < 0.0001), orientation attendance (96.3 vs 37.1%, P < 0.0001), program participation (87.8% vs 33.5%, P < 0.0001), and completion (71.4% vs 29.9%, P < 0.001) compared to the matched historical comparison group. CONCLUSIONS The utilization of the ECAC model resulted in an unprecedented (∼3-fold) increase in the number of post-STEMI patients participating in CR. Given the unequivocal mortality and morbidity benefits of CR, adoption of the ECAC model has important clinical and economic relevance.

Relation between flow grade after thrombolytic therapy and the effect of angioplasty on left ventricular function: A prospective randomized trial

Recent intervention trials during myocardial infarction demonstrated no benefit from emergency angioplasty after thrombolytic therapy when compared with either delayed percutaneous transluminal coronary angioplasty (PTCA) or a conservative strategy. However, it is possible that subgroups of patients may benefit from early intervention with angioplasty. We performed a prospective randomized trial in patients with a patent infarct-related artery after thrombolytic therapy to determine whether initial flow grade is related to infarct-zone function and whether patients with ineffective reperfusion (greater than 90% stenosis or Thrombolysis in Myocardial Infarction [TIMI] flow less than or equal to 2) might benefit from immediate PTCA. Thrombolytic therapy was administered to 170 patients at a mean of 2.1 +/- 0.5 hours after onset of myocardial infarction. A patent infarct-related artery that was suitable for angioplasty was present in 89 patients who comprised the study group; after randomization, 47 of 50 patients with a patent infarct-related artery had successful emergency PTCA 3.8 +/- 1.5 hours after onset of symptoms, and 39 were scheduled for delayed (18 to 48-hour) PTCA. Reocclusion occurred before the scheduled (delayed) procedure in eight patients (20.5%), and was symptomatic in six. Infarct-region function (by the centerline method) measured initially, before discharge, and at 4 months was similar in both groups; improvement was significant (p less than 0.001) at discharge when compared with initial values with no further change at 4 months. However, patients with ineffective reperfusion had greater hypokinesia initially (p less than 0.05) compared with those with effective reperfusion (less than or equal to 90% stenosis plus TIMI flow 3). Moreover, independent of the timing of PTCA, improvement was greater before discharge in patients with ineffective reperfusion (p less than 0.05) with a trend also evident at 4 months. Importantly, 42 of 51 patients (82%) with a residual lumen less than 0.4 mm after thrombolysis had some improvement in function at discharge; this compared with a previous study in which patients with a similar degree of stenosis (without PTCA) had no improvement. Moreover, reocclusion occurred before scheduled (delayed) PTCA in 37% of patients with greater than 90% stenosis compared with only 5% in those with less than or equal to 90% stenosis (p = 0.02). Thus flow grade is an important determinant of myocardial function in patients with a patent artery after thrombolytic therapy and is predictive both of improvement in wall motion after PTCA and early reocclusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Antiarrhythmic drug effects on QT interval dispersion in patients undergoing electropharmacologic testing for ventricular tachycardia and fibrillation

The effects of antiarrhythmic drugs on QT interval dispersion as a predictor of antiarrhythmic drug therapy has not been rigorously assessed. This study was performed to determine whether the effects of antiarrhythmic drugs on QT interval dispersion predict antiarrhythmic drug response in patients undergoing electropharmacologic testing for ventricular tachycardiarrythmias. Precordial QT intervals and QT interval dispersions were measured at baseline and during steady-state antiarrhythmic drug therapy in 72 consecutive patients with documented coronary artery disease and remote myocardial infarction presenting with spontaneous sustained ventricular tachyarrhythmias who underwent electropharmacologic studies to assess arrhythmia suppression. QT interval dispersion was similar at baseline in drug responders (42 +/- 21 ms) and drug nonresponders (46 +/- 21 ms), whereas during antiarrhythmic therapy QT interval dispersion was shorter in drug responders (33 +/- 15 ms) than in drug nonresponders (55 +/- 29 ms, p <0.001). QT interval dispersion was shorter in 7 drug responders during their effective drug trials (27 +/- 14 ms) than during their ineffective drug trials (47 +/- 24 ms, n = 9, p <0.05). QT dispersion < or = 50 ms (p <0.002) and a patent infarct-related artery (p <0.003) were independent predictors of antiarrhythmic therapy. The positive and negative predictive value of QT interval dispersion during drug therapy to predict a successful drug response was 32% and 96%, respectively. QT interval dispersion predicted the outcome of electropharmacologic studies independent of infarct-related artery patency. QT interval dispersion >50 ms during drug therapy was associated with ineffective drug therapy.

The right and left ventricular intracavitary and transmural pressure-strain relationships

The magnitude of pericardial pressure and therefore the shape of the right ventricular end-diastolic transmural pressure-volume relationship remains controversial. To investigate ventricular compliance, eight dogs anesthetized with fentanyl were instrumented as follows. Right and left ventricular intracavitary pressures were measured with micromanometer-tipped catheters. Right and left ventricular free wall segment lengths were measured by sonomicrometry. Pericardial pressure was measured over the right and left ventricles by means of flat liquid-containing balloon transducers, and transmural pressures were calculated as the difference between intracavitary and pericardial pressures. After defining the pressure-segment length relationship by vena caval constriction followed by release and blood transfusion, the pericardium and chest were opened widely and the cardiac volume manipulation was repeated; this allowed direct measurement of transmural right ventricular end-diastolic pressure for each level of strain recorded with the chest and pericardium closed. When intracavitary right or left ventricular end-diastolic pressure was raised from zero to 20 mm Hg, the respective transmural pressures increased from 0.2 +/- 0.6 (SD) mm Hg to 2.5 +/- 1.8 mm Hg and from 0.3 +/- 0.7 mm Hg to 6.0 +/- 2.5 mm Hg. Ventricular segmental strain increased by 7.0 +/- 0.8% and 6.0 +/- 0.2%, respectively. No statistically significant differences were found between right ventricular calculated (intracavitary minus pericardial pressure) and measured (open pericardium, open chest) transmural pressures at a given strain, thereby confirming the accuracy of our pericardial pressure measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Cirrhotic cardiomyopathy: Implications for liver transplantation

The majority of patients on a waiting list for liver transplantation have end‐stage liver disease. Because of the marked peripheral vasodilatation of end‐stage cirrhosis that masks a latent myocardial dysfunction, cardiac abnormalities in the resting state are usually subclinical and escape the attention of physicians. However, when challenged, the systolic and diastolic contractile responses are attenuated. In addition to these contractile abnormalities, morphological changes, such as enlargement or hypertrophy of cardiac chambers, and electrophysiological repolarization changes, including a prolonged QT interval, can be observed. The constellation of these cardiac abnormalities is termed cirrhotic cardiomyopathy. Liver transplantation induces significant cardiovascular stress. Clamping of the inferior vena cava and portal vein, hemorrhage and blood/volume infusion, and ischemia/reperfusion all cause hemodynamic fluctuation. The changing cardiac preload and afterload status increases the cardiac workload, and thus, the previously subclinical ventricular dysfunction may manifest as overt heart failure during the operative and perioperative periods. Cardiac dysfunction contributes to morbidity and mortality associated with liver transplantation. Cardiovascular events are the third leading cause of death in liver recipients. However, because liver transplantation is the only definitive treatment for end‐stage liver failure and also appears to reverse cardiac abnormalities, it is important to understand the challenges of the heart in liver transplantation. This review focuses on cardiac status before, during, and after liver transplantation. Liver Transplantation 23 826–835 2017 AASLD.

Long-term outcomes of patients receiving drug-eluting stents

Background: We sought to establish the long-term safety of drug-eluting stents compared with bare-metal stents in a usual care setting. Methods: Using data from a prospective multicentre registry, we compared rates of death and of death or repeat revascularization during 3 years of follow-up of 6440 consecutive patients who underwent angioplasty with either drug-eluting or bare-metal stents between Apr. 1, 2003, and Mar. 31, 2006. Results: Drug-eluting stents were inserted in 1120 patients and bare-metal stents in 5320. The drug-eluting stents were selected for patients who had a greater burden of comorbid illness, including diabetes mellitus (32.8% v. 20.8% in the bare-metal group, p < 0.001) and renal disease (7.4% v. 5.0%, p = 0.001). At 1-year follow-up, the drug-eluting stents were associated with a mortality of 3.0%, as compared with 3.7% with the bare-metal stents (adjusted odds ratio [OR] 0.62, 95% confidence interval [CI] 0.46–0.83). The rate of the composite outcome of death or repeat revascularization was 12.0% for the drug-eluting stents and 15.8% for the bare-metal stents (adjusted OR 0.40, 95% CI 0.33–0.49). In the subgroup of patients who had acute coronary syndromes, the adjusted OR for this composite outcome was 0.46 (95% CI 0.35–0.61). During the 3 years of observation, the relative risks for death and repeat revascularization varied over time. In year 1, there was an initial period of lower risk in the group with drug-eluting stents than in the group with bare-metal stents; this was followed by a shift toward outcome rates favouring bare-metal stents in years 2 and 3. The adjusted relative risk of the composite outcome of death or repeat revascularization associated with drug-eluting stents relative to bare-metal stents was 0.73 early in the first year of follow-up; it then rose gradually over time, to a peak of 2.24 at 3 years. Interpretation: Drug-eluting stents are safe and effective in the first year following insertion. Thereafter, the possibility of longer term adverse events cannot be ruled out.

Outcomes of after-hours versus regular working hours primary percutaneous coronary intervention for acute myocardial infarction

Background Primary percutaneous coronary intervention (PCI) is a proven therapy for acute ST-segment elevation myocardial infarction. However, outcomes associated with primary PCI may differ depending on time of day. Methods and results Using the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease, a clinical data-collection initiative capturing all cardiac catheterisation patients in Alberta, Canada, the authors described and compared crude and risk-adjusted survival for ST-segment elevation myocardial infarction patients undergoing primary PCI after-hours versus regular working hours. From 1 January 1999 to 31 March 2006, 1664 primary PCI procedures were performed (54.4% after-hours). Mortalities at 30 days were 3.6% for regular hours procedures and 5.0% for after-hours procedures (p=0.16). 1-year mortalities were 6.2% and 7.3% in the regular hours and after-hours groups, respectively (p=0.35). After adjusting for baseline risk factor differences, HRs for after-hours mortality were 1.26 (95% CI 0.78 to 2.02) for survival to 30 days and 1.08 (0.73 to 1.59) for survival to 1 year. A meta-analysis of our after-hours HR point estimate with other published risk estimates for after hours primary PCI outcomes yielded an RR of 1.23 (1.00 to 1.51) for shorter-term outcomes. Conclusions After-hours primary PCI was not associated with a statistically significant increase in mortality. However, a meta-analysis of this study with other published after-hours outcome studies yields an RR that leaves some questions about unexplored factors that may influence after-hours primary PCI care.

Diagnosis and management of acute ischemic stroke: speed is critical

Globally, stroke is the second leading cause of death.[1][1] The estimated 62 000 strokes that occur each year in Canada affect all age groups, from neonates to elderly people, with occurrence rates rising by age. The lifetime risk of overt stroke is estimated at one in four by age 80 years, and the