Title: Risk for Incident Atrial Fibrillation in Patients Who Receive Antihypertensive Drugs: A Nested Case-Control Study
Topic: Arrhythmias
Date Posted: 1/26/2010
Author(s): Schaer BA, Schneider C, Jick SS, Conen D, Osswald S, Meier CR.
Citation: Ann Intern Med 2010;152:78-84.
Clinical Trial: No
Study Question: Is the risk of developing atrial fibrillation (AF) affected by the type of medication used to treat hypertension?
Methods: The subjects of this retrospective study were selected from a primary-care database in the United Kingdom and all received monotherapy for hypertension. There were 4,661 patients who developed AF during follow-up and 18,642 matched control subjects who did not. Approximately 70% of patients in both groups were at least 70 years old. The class of drug used to treat the hypertension was analyzed in both groups.
Results: Compared to patients whose hypertension was treated with a calcium-channel blocker (CCB), recipients of an angiotension-converting enzyme inhibitor (ACEI) had a 25% lower risk of developing AF, recipients of an angiotension II-receptor blocker (ARB) had a 29% lower risk, and recipients of a beta-blocker had a 22% lower risk.
Conclusions: Treatment of hypertension with an ACEI, ARB, or beta-blocker reduces the risk of new-onset AF compared to CCBs.
Perspective: Several prior studies have demonstrated that ACEIs and ARBs reduce the risk of AF. Possible mechanisms include lowering of blood pressure, prevention or treatment of heart failure, and prevention of atrial fibrosis. CCBs lower the blood pressure, but do not prevent heart failure or atrial fibrosis. Therefore, the results of this study suggest that prevention of heart failure and/or atrial fibrosis explain the lower risk of AF when hypertension is treated with an ACEI, ARB, or beta-blockers. However, it should be noted that the study does not rule out the possibility of a proarrhythmic effect of CCBs compared to a neutral effect of ACEIs, ARBs, and beta-blockers on the risk of AF. Fred Morady, M.D., F.A.C.C.
Title: Aortic Elasticity and Size Are Associated With Aortic Regurgitation and Left Ventricular Dysfunction in Tetralogy of Fallot After Pulmonary Valve Replacement
Topic: Congenital Heart Disease
Date Posted: 1/26/2010
Author(s): Grotenhuis HB, Ottenkamp J, de Bruijn L, et al.
Citation: Heart 2009;95:1931-1936.
Clinical Trial: No
Study Question: What are the relationships between aortic elasticity, aortic valve competence, and biventricular function in patients with repaired tetralogy of Fallot (TOF) who have undergone pulmonary valve replacement?
Methods: A prospective case-controlled study was performed. Sixteen patients with TOF and 16 age- and gender-matched controls underwent cardiac magnetic resonance imaging for evaluation of aortic root dimensions, biventricular function, aortic elasticity, and quantification of aortic regurgitation.
Results: Aortic root dimensions at the sinuses of ******** were larger in the TOF patients (39.3 ± 5.4) compared with the controls (30.4 ± 3.1). Reduced aortic elasticity was also seen in the TOF group (pulse wave velocity in the aortic arch of 5.5 ± 1.2 m/s compared with 4.6 ± 0.9 m/s). TOF patients were also found to have increased aortic regurgitation (regurgitant fraction of 6% vs. 1%, p < 0.01) and decreased left ventricular ejection fraction (LVEF) (51% vs. 58%, p = 0.01), whereas right ventricular ejection fraction (RVEF) was preserved in both groups. The degree of aortic regurgitation fraction was associated with dilatation of the aortic root (r = 0.39-0.49, p < 0.05) and reduced aortic root distensibility (r = 0.44, p = 0.02). Reduced LVEF correlated with degree of aortic regurgitation and RVEF (r = 0.41, p = 0.02 and r = 0.49, p < 0.01, respectively).
Conclusions: Aortic root dilatation and reduced aortic elasticity are frequently seen in patients following repair of TOF and pulmonary valve replacement. Aortic wall pathology may contribute to LV dysfunction in this patient population.
Perspective: This paper studies the relationship between aortic root pathology and LV function in patients following TOF repair and subsequent pulmonary valve replacement. LV dysfunction has been well-documented in patients after TOF repair, and has often been attributed to intraventricular dependence, as well as perioperative insults with early bypass techniques. This study shows a relationship between relatively mild degrees of aortic insufficiency and root dilatation with LV dysfunction. Although the correlation coefficients are relatively weak, it appears that this was a consistent finding in a relatively small patient population. This study emphasizes the complexity of etiologies contributing to LV dysfunction in patients following repair of TOF. Timothy B. Cotts, M.D., F.A.C.C.