Leveraging Clinical Digitized Data to Understand Temporal Characteristics and Outcomes of Acute Myocardial Infarctions at a Tertiary Care Medical Centre in Pakistan from 1988–2018 – Methods and Results

Background and Objective:Few data exist on trends in acute myocardial infarction (AMI) patterns spanning recent epidemiological shifts in low middle-income countries (LMICs). To understand temporal disease patterns of AMI characteristics and outcomes between 1988–2018, we used digitized legacy clinical data at a large tertiary care centre in Pakistan.Methods:We reviewed digital health information capture systems maintained across the Aga Khan University Hospital and obtained structured elements to create a master dataset. We included index admissions of patients >18 years that were discharged between January 1, 1988, and December 31, 2018, with a primary discharge diagnosis of AMI (using ICD-9 diagnoses). The outcome evaluated was in-hospital mortality.Clinical characteristics derived from the electronic database were validated against chart review in a random sample of cases (k 0.53–1.00).Results:The final population consisted of 14,601 patients of which 30.6% (n = 4,470) were female, 52.4% (n = 7,651) had ST elevation MI and 47.6% (n = 6,950) had non-ST elevation MI. The median (IQR) age at presentation was 61 (52–70) years. Overall unadjusted in-hospital mortality was 10.3%. Across the time period, increasing trends were noted for the following characteristics: age, proportion of women, prevalence of hypertension, diabetes, proportion with NSTEMI (all p_trend < 0.001). In-hospital mortality rates declined significantly between 1988–1997 and 2008–2018 (13.8% to 9.2%, p < 0.001).Conclusions:The patterns of AMI have changed over the last three decades with a concomitant decline in in-hospital mortality at a tertiary care centre in Pakistan. Clinical digitized data presents a unique opportunity for gaining insights into disease patterns in LMICs.     

Meta-Analysis of Short vs. Prolonged Dual Antiplatelet Therapy after Drug-Eluting Stent Implantation and Role of Continuation with either Aspirin or a P2Y12 Inhibitor Thereafter

Aim: The optimal duration of dual antiplatelet therapy (DAPT) after drug-eluting stent (DES) implantation is an ongoing debate and novel data has emerged. The aim of this meta-analysis was to assess outcomes of short vs. control DAPT duration. In addition, the role of single antiplatelet therapy (SAPT) after DAPT with either aspirin or P2Y₁₂ inhibitor monotherapy was analyzed. Methods: The authors searched MEDLINE and Cochrane databases and proceedings of international meetings for randomized controlled trials (RCT) comparing ≤ 3 months with ≥ 6 months DAPT after DES implantation. The primary and co-primary outcomes of interest were definite or probable stent thrombosis (ST) and bleeding. In addition, we performed an analysis on studies who continued with either aspirin or P2Y₁₂ monotherapy after DAPT. Results: 9 RCTs comprising 41,864 patients were included and we analyzed a short DAPT duration of median 1.5 months vs. 12.1 months in the control group. The risk for ST was similar with short vs. control DAPT duration (0.5 vs. 0.5%; hazard ratio 1.17[95% CI 0.89-1.54];p=0.26). Bleeding was significantly reduced with short vs. control DAPT duration (1.9 vs. 3.0%; 0.65[0.54-0.77];p＜0.0001). ST was not different between short vs. control DAPT duration in the analysis of the 4 RCTs who continued with aspirin after DAPT and the 5 P2Y₁₂ RCTs, respectively, and no heterogeneity was detected (p=0.861). Bleeding was also reduced with short vs. control DAPT in both the aspirin (1.2 vs. 1.7%; 0.71[0.51-0.99];p=0.04) and P2Y₁₂ inhibitor studies (2.1 vs. 3.4%; 0.62[0.47-0.80];p=0.0003) and no heterogeneity was detected (p=0.515). Conclusions: Our meta-analysis shows that short DAPT ≤ 3 months followed by SAPT reduces bleeding and is not associated with an increase in ST. The results were consistent within the aspirin and P2Y₁₂ SAPT studies.     

Troponin level and efficacy of abciximab in patients with acute coronary syndromes undergoing early intervention after clopidogrel pretreatment

Objective We investigated how does troponin level (TnT) affect the benefit achieved by abciximab in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI) after pretreatment with a high loading dose of clopidogrel. Methods The Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment (ISAR-REACT 2) trial included 2,022 patients with non-ST elevation ACS undergoing PCI who were randomized to abciximab or placebo after pretreatment with 600 mg of clopidogrel. The patients were divided into groups with elevated TnT level (n = 1,049) and no elevated TnT level (n = 973). The primary end point of the trial was the composite of death, myocardial infarction and urgent reintervention at 30 days. Results In patients with elevated TnT level the incidence of the primary end point was 13.1% in the abciximab group Vs. 18.3% in the placebo group [relative risk (RR): 0.70; 95% confidence interval (CI), 0.52–0.95, P = 0.02]. The combined incidence of death or myocardial infarction was 12.9% in the abciximab group vs. 17.9% in the placebo group (RR: 0.71; 95% CI, 0.52–0.96, P = 0.03). In contrast, the incidence of the primary end point in patients with no elevated TnT level was identical in both treatment groups (4.6%). The risk of bleeding was not related to TnT level. Conclusions Baseline troponin level affects the benefit of abciximab in patients with ACS undergoing PCI after pretreatment with a high loading dose of clopidogrel. Abciximab reduces the risk of ischemic events only in patients with ACS and elevated troponin level.     

Color Doppler tissue imaging to evaluate left atrial appendage function in mitral stenosis

Two-dimensional color Doppler tissue imaging (CDTI) has so far been used, in general, to evaluate ventricular function. This study examined if the left atrial appendage tissue velocity could reproducibly be measured with CDTI and if they have any predictive value for left atrial appendage (LAA) function and former thromboembolism. Thirty-six patients (24 women, 12 men; mean age 45 +/- 12 years; 18 AF; 11 former thromboembolic stroke) with mitral stenosis undergoing transesophageal echocardiography were examined with CDTI. Peak systolic tissue velocity (m/sec, peak systolic velocity [PSV]) was measured at the tip of the LAA in the basal short-axis view. LAA flow emptying (LAAEV) and filling (LAAFV) velocities (m/sec) were also recorded 1 cm immediately below the orifice of the appendage. Interobserver and intraobserver variabilities were determined for the PSV. LAA ejection fraction was measured by Simpson's method. Mitral regurgitation, AF, transmitral mean gradient, left ventricular ejection fraction, mitral valve area, and left atrial diameter were used as a covariant for adjustment. The intraobserver and interobserver correlation coefficients for the PSV using CDTI was 0.64 and 0.60, respectively (bothP = 0.01). LAAEV(0.29 +/- 0.09 vs 0.19 +/- 0.04, P = 0.001)and LAA ejection fraction(44 +/- 12 vs 29 +/- 14, P = 0.004)were found to be significantly decreased in the patients with decreased PSV (<0.05 m/sec), even after adjustment. The decreased PSV was positively correlated with the low LAAEV (<0.25 m/sec) and history of thromboembolism (r = 0.59, r = 0.38, respectively), and remained a significant determinant of the low LAAEV (OR 50.03, CI 1.46-1738.11,P = 0.02), but not of history of thromboembolism (OR 4.29, CI 0.52-35.01,P = 0.08) after adjustment. In conclusion, these results suggest that CDTI provides a reproducible method for quantification of contraction at the tip of the LAA. Decreased PSV may be predictive of poor LAA function.