Ammar, Khawaja Afzal

AbstractBackgroundSilent or unrecognized myocardial infarction (UMI) diagnosed by surveillance electrocardiography (ECG) carries similarly poor prognosis as recognized MI (RMI) for poorly understood reasons.MethodsThis study included 5430 consecutive patients who presented to the nuclear laboratory and underwent 2‐day stress and rest Tc‐99m sestamibi and ECG studies between March 1991 and June 1999. UMI was diagnosed if ECG showed Q‐wave MI in the absence of a history of RMI. We measured infarct size (% defect size as compared with the entire left ventricular sestamibi uptake), ejection fraction (EF, %), and summed difference score (SDS, sestamibi uptake by myocardium in stress minus sestamibi uptake in rest images as a marker of ischemia). Survival was determined by follow‐up survey (median 6 years).ResultsWe identified 346 UMIs, 628 RMIs, and 4456 subjects without MI (No MI). As compared with RMI, UMI patients had lesser abnormalities on nuclear scans (p < .0001 for all), including smaller infarct size (5.7% vs. 12.2%), higher EF (58% vs. 53%), and lesser ischemia (SDS; 3.9% vs. 2.7%). UMI prognosis was as poor as that of RMI (annual mortality rate 4.7% vs. 4.8% with No MI rate of 2.9%; p < .001 for all comparisons), and this persisted after multivariate analysis. Infarct size quantification successfully risk‐stratified ECG‐UMI patients, but UMI patients continued to predict mortality even if the infarct size was 0%.ConclusionsAlthough UMI patients have lesser abnormalities on nuclear scans, ECG‐based UMI continues to independently predict mortality, indicating the continuing relevance of ECG in clinical practice.

Background : Unrecognized myocardial infarction (UMI), as diagnosed by surveillance electrocardiography (ECG), has the same poor prognosis as recognized (RMI), independent of ejection fraction or ischemia. The value of post UMI risk stratification by infarct size is unknown. Methods : The study group consisted of 5430 patients who underwent 2 day stress (exercise n = 191, pharmacologic n = 155) and rest Tc-99m sestamibi SPECT studies. UMI was diagnosed if ECG showed Q wave MI in the absence of history of MI. SPECT infarct size was quantitated based on a 60% of peak counts threshold method and was expressed as a percentage of the left ventricle (% LV). The association between infarct size and mortality was adjusted for clinical and exercise test prognostic scoring systems. Results : The population consisted of 346 UMI, 628 RMI, and 4456 patients without MI (No MI). Compared to No MI, mortality risk was increased in UMI (RR 1.7, 95% CI 1.6–1.9; p < 0.001) and RMI (RR 1.6, 95% CI 1.4–1.9; p < 0.001) patients. In the UMI group, infarct size was significantly associated with mortality ( p < 0.001), which persisted after adjustment for Mayo prognostic score alone (available in all patients) ( p < 0.001) and for Mayo prognostic score, Framingham risk score, and Duke treadmill score (data available in 137 patients) ( p < 0.001). For every 10% LV increase in infarct size, mortality risk increased 30% (RR = 1.3, 95% CI 1.2–1.5) (see figure ). Conclusions: In patients with UMI, larger quantitated SPECT infarct size predicts increased mortality independent of clinical and exercise test prognostic scoring systems. This finding supports the use of infarct size imaging for risk stratification of UMI patients.

Background— Heart failure (HF) is a progressive disorder associated with frequent morbidity and mortality. An American Heart Association/American College of Cardiology staging classification of HF has been developed to emphasize early detection and prevention. The prevalence of HF stages and their association with mortality are unknown. We sought to estimate HF stage prevalence in the community and to measure the association of HF stages with mortality. Methods and Results— A population-based, cross-sectional, random sample of 2029 Olmsted County, Minnesota, residents aged ≥45 years was identified. Participants were classified by medical record review, symptom questionnaire, physical examination, and echocardiogram as follows: stage 0, healthy; stage A, HF risk factors; stage B, asymptomatic cardiac structural or functional abnormalities; stage C, HF symptoms; and stage D, severe HF. In the cohort, 32% were stage 0, 22% stage A, 34% stage B, 12% stage C, and 0.2% stage D. Mean B-type natriuretic peptide concentrations (in pg/mL) increased by stages: stage 0=26, stage A=32, stage B=53, stage C=137, and stage D=353. Survival at 5 years was 99% in stage 0, 97% in stage A, 96% in stage B, 75% in stage C, and 20% in stage D. Conclusions— The present study provides prevalence estimates and prognostic validation for HF staging in a community cohort. Of note, 56% of adults ≥45 years of age were classified as being in stage A (risk factors) or B (asymptomatic ventricular dysfunction). HF staging underscores the magnitude of the population at risk for progression to overt HF.