Abstract-Low heart rate (HR) variability is associated with increased risk of cardiovascular morbidity and mortality, but the causes and mechanisms of this association are not well known. This prospective study was designed to test the hypothesis that reduced HR variability is related to progression of coronary atherosclerosis. Average HR and HR variability were analyzed in 12-hour ambulatory ECG recordings from 265 qualified patients participating in a multicenter study to evaluate the angiographic progression of coronary artery disease in patients with prior coronary artery bypass surgery and low high-density lipoprotein cholesterol concentrations (Ͻ1.1 mmol/L). Participants were randomized to receive a placebo or gemfibrozil therapy. The progression of coronary atherosclerosis was estimated by quantitative, computer-assisted analysis of coronary artery stenoses from the baseline angiograms and from repeated angiograms performed an average of 32 months later. The progression of focal coronary atherosclerosis of the patients randomized to placebo therapy was more marked in the tertile with the lowest standard deviation of all normal to normal R-R intervals ( Key Words: coronary artery disease Ⅲ lipids Ⅲ heart period Ⅲ angiography E levated heart rate (HR) and reduced HR variability are associated with an increased risk of cardiovascular morbidity and mortality in various populations, 1-8 but the pathophysiological link between these associations is not well understood. Experimental studies on monkeys fed an atherogenic diet have demonstrated a relationship between resting HR and progression of coronary atherosclerosis, 9 -11 and there is also a strong relationship between HR and arterial stiffness, 12 but there has been little evidence of any association between HR, or its variability, and human coronary atherosclerosis.Progression of coronary artery stenoses in repeated coronary angiograms increases the risk of adverse cardiac events, suggesting that rapid progression predisposes patients to acute complications of coronary artery plaques and serves as a surrogate end point for clinical events. 13,14 Lipid-modifying therapy has been shown to prevent the progression of coronary atherosclerosis, confirming that abnormalities in plasma lipid concentrations are strongly associated with the progression of coronary artery disease and the occurrence of adverse clinical events. 14 However, lipid theory may not explain all aspects of coronary artery disease, eg, the rapid progression of discrete stenoses in specific coronary arterial regions, which is thought to result from an interplay of hemodynamic, metabolic, and hemostatic factors. [15][16][17][18] To test the hypothesis that elevated HR and reduced HR variability are associated with the progression of human coronary atherosclerosis in patients with lipid abnormalities, we studied HR and its variability, measured by ambulatory ECG, and the angiographic progression of coronary artery disease in patients with reduced HDL cholesterol concentrations.

Cardiac Arrhythmias and Risk Stratification after Myocardial infarction (CARISMA) is a prospective multicenter trial designed to document the incidence of cardiac arrhythmias after acute myocardial infarction (AMI), and to assess the predictive accuracy of various arrhythmic risk markers. In this substudy of the CARISMA trial, microvolt T-wave alternans (TWA) was assessed with specific equipment 6 weeks after AMI during bicycle exercise, atrial (A) pacing, and simultaneous ventricular and atrial (V + A) pacing in 80 patients with left ventricular ejection fraction (LVEF) <40%. The agreement between the acute test results was determined by overall proportion of concordance and the kappa statistic. Sustained TWA was observed in 24, 45, and 50% of the patients during the exercise test, A pacing, and V + A pacing, respectively. The number of indeterminate TWA was significantly lower during V + A pacing (n = 7) than exercise test (n = 34). The TWA concordance rate was 71% between exercise and V + A pacing (kappa= 0.53, P = 0.001), 79% between exercise and A pacing (kappa= 0.54, P < 0.001), and 95% between the two pacing modes (kappa= 0.89, P < 0.001). Patients with positive TWA in all tests had lower LVEF (28 +/- 7% vs 35 +/- 9%, P < 0.01) and wider QT dispersion (99 +/- 44 ms vs 67 +/- 38 ms, P < 0.01) than those with inconsistent test result. The low number of indeterminate tests and high concordance between the test results indicate that V + A pacing may provide a valuable means to assess TWA in patients who cannot complete the exercise test.

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PCI with DES for selected LMCA disease patients results in short- and midterm outcomes comparable to results of CABG in general. PCI is a viable therapeutic option in selected patients with LMCA stenosis.