Low-dose aspirin for primary prevention of cardiovascular events in patients with diabetes: Benefit or risk?

Primary prevention aims to avert the onset of cardiovascular disease (CVD) by targeting its natural causes and risk factors; secondary prevention includes strategies and therapies that address preclinical or clinical evidence of CVD progression. The value of aspirin for primary CVD prevention is controversial because of increased bleeding, which may offset the overall modest benefits in patients with no overt CVD. In contrast, the benefits of aspirin for secondary prevention have been repeatedly and convincingly demonstrated to outweigh the risk of bleeding. Diabetes mellitus is a strong risk factor for cardiovascular events, and has been associated with an increased risk of both first and recurrent atherothrombotic events. Therefore, prevention of CVD, the major cause of mortality in patients with diabetes, is one of the most important therapeutic goals. Although the benefit of low-dose aspirin for secondary prevention of CVD is well established, its role for primary prevention remains inconclusive and controversial in diabetes patients. The benefit of aspirin for patients with CVD clearly exceeds the risk of bleeding, and even though a modest benefit has also been demonstrated in primary prevention, the trade-off for aspirin initiation against the increased risk of intracranial and gastrointestinal bleeding is more uncertain. Thus, aspirin for primary CVD prevention should be highly individualized, based on a benefit-risk ratio assessment for the given patient. In conclusion, the mere presence of diabetes is apparently not enough for aspirin to confer a benefit that clearly outweighs the risk of bleeding, and further evidence to the contrary is now needed.

Prognostic role of heart rate variability in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: The aim of this study was to investigate whether heart rate variability may predict the outcome in patients with idiopathic dilated cardiomyopathy. METHODS: Time-domain and frequency-domain heart rate variability was analyzed on 24-hour Holter recordings of 56 patients with idiopathic dilated cardiomyopathy (70% males, mean age 49 +/- 16 years; left ventricular ejection fraction 28 +/- 6%). RESULTS: There were 8 cardiac deaths (14.3%) and 11 arrhythmic events (19.6%, either sudden death or sustained ventricular tachycardia) at a follow-up of 18.5 months (range 3-50 months). Furthermore, 6 patients were included in the list for cardiac transplantation, leading to a prevalence of total cardiac events of 37.5 % (21 patients). All time-domain and most frequency-domain heart rate variability parameters did not show any significant relationship with the end points. However, a low frequency to high frequency (LF/HF) ratio < 1.2 was associated with cardiac death (relative risk-RR 6.8, p < 0.03), arrhythmic events (RR 11.0, p < 0.004), and total cardiac events (RR 4.8, p < 0.002). On the multivariate Cox analysis, no variable showed an independent association with cardiac death, but an LF/HF ratio < 1.2 was the only variable independently predictive of arrhythmic events (RR 8.2, p < 0.02), and the most powerful predictor of total cardiac events (RR 3.8, p < 0.009). CONCLUSIONS: Our data show that, in patients with idiopathic dilated cardiomyopathy, a low LF/HF ratio, as assessed on 24-hour Holter recordings, is a powerful predictor of cardiac events.

Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways.

BACKGROUND: Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff-Parkinson-White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. METHODS AND RESULTS: One hundred patients with Wolff-Parkinson-White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V-A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30-250 Hz) "unipolar" electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A-K); (2) from the onset of the delta wave to the onset of the K potential (delta-K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K-V). During unsuccessful versus successful attempts, A-K (51 +/- 11 ms vs 28 +/- 8 ms, P < 0.0001 for left pathways [LPs]; and 44 +/- 8 ms vs 31 +/- 8 ms, P < 0.02 for right pathways [RPs]) and delta-K intervals (2 +/- 9 ms vs -18 +/- 10 ms, P < 0.0001 for LPs; and 13 +/- 7 ms vs 5 +/- 8 ms, P < 0.02 ms for RPs) were significantly longer. CONCLUSIONS: Short A-K interval (< 40 ms), and a negative delta-K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A-K and delta-K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A-K and delta-K interval.

Catheter ablation of left accessory atrioventricular connections: the transseptal approach.

BACKGROUND: In the past few years, there has been a relative explosion of activity in the realm of interventional cardiology. The high rate of success of radiofrequency energy ablation have transformed catheter ablation from an investigational procedure into the first-line therapy for symptomatic Wolff-Parkinson-White syndrome. Radiofrequency catheter ablation for preexcitation syndrome is commonly based on a ventricular approach. Such an approach might be associated with the risk of prolonged arterial catheter manipulation, retrograde left ventricular catheterization, and production of multiple, potentially arrhythmogenic, ventricular lesions created during ablation. Potential risks can be avoided using atrial insertion ablation procedures. The transseptal procedure that was developed in the 1950s and 1960s as a diagnostic procedure and then shelved in the 1970s and early 1980s has now come back into prominence as a therapeutic technique in the treatment of valvular heart disease, and then in the ablation of the left accessory atrioventricular connections. METHODS: Atrial aspect of mitral annulus is a relatively smooth, nonobstructed surface that simplifies catheter movement, thereby permitting rapid and accurate accessory pathway location. Although primary use of earliest endocardial retrograde atrial activation as a marker of accessory pathway atrial insertion is sufficiently accurate to permit successful ablation, direct recording of an accessory pathway potential is an important predictor of successful ablation site. Moreover, the analysis of the unipolar atrial electrogram, recorded during sinus rhythm from the tip of the ablation catheter, provides further information for localizing the atrial insertion of the accessory pathways. Shortest atrial-accessory pathway and negative delta-accessory pathway intervals have been found to be the best predictors of the successful site. RESULTS: A 90.5% success of the transseptal approach on an overall population of 328 patients, higher for overt than for concealed pathways, is comparable with the results of the retrograde. Complications are 0.5%. CONCLUSION: In conclusion, the transseptal approach for ablation at the atrial site is very safe and highly effective, and avoids prolonged arterial cannulation and catheter manipulation in the ascending aorta and left ventricle.