Effect of mitral isthmus block on development of atrial tachycardia following ablation for atrial fibrillation.

BACKGROUND: Successful mitral isthmus (MI) ablation may reduce recurrence of atrial fibrillation (AF) and macro-reentrant atrial tachycardia (AT) after pulmonary vein isolation (PVI) for AF. OBJECTIVE: To determine if achieving bidirectional MI conduction block (MIB) during circumferential pulmonary vein ablation (CPVA) plus left atrial linear ablation (LALA) affects development of AT. METHODS: Sixty consecutive patients with persistent (n = 25) or paroxysmal (n = 35) AF undergoing CPVA plus LALA at the MI and LA roof were evaluated in a prospective, nonrandomized study. RESULTS: PVI was achieved in all patients. Bidirectional MI block was achieved in 50 of 60 patients (83%). During 18 +/- 5 months follow-up, 12 patients (20%) developed recurrent AF and 15 (25%) developed AT. Patients in whom MIB was not achieved at initial ablation had four times higher risk of developing AT (P = 0.008, 95% confidence interval 1.43-11.48) versus patients with MIB. In 12 patients with AT undergoing repeat ablation, 22 ATs were identified, with reentry involving the MI in nine, the LA roof in six, and the ridge between the LA appendage and left PVs in seven. In patients with MIB at initial ablation, recovery of MI conduction was seen in eight of 13 undergoing repeat ablation. CONCLUSIONS: AT occurring after CPVA plus LALA is often due to incomplete MI ablation, but may also occur at the LA roof, and ridge between the LA appendage and left PVs. Failure to achieve MI block increases the risk of developing AT. Resumption of MI conduction may also be a mechanism for AT recurrence. (PACE 2010; 460-468).

Prediction of coronary heart disease by erectile dysfunction in men referred for nuclear stress testing.

BACKGROUND: Recent evidence suggests a strong link between erectile dysfunction (ED) and atherosclerotic vascular disease. Stress myocardial perfusion single-photon emission computed tomography (MPS) is a widely used noninvasive imaging modality that allows diagnosis of coronary heart disease and stratification of cardiovascular risk. We sought to determine the relationship between ED and coronary heart disease in men referred for MPS. METHODS: A total of 221 men referred for MPS were prospectively screened for ED with a validated questionnaire. Patient characteristics, MPS findings, and exercise results were correlated with ED. RESULTS: Erectile dysfunction was present in 54.8% of the patients. Patients with ED exhibited more severe coronary heart disease (MPS summed stress score >8) (43.0% vs 17.0%; P<.001) and left ventricular dysfunction (left ventricular ejection fraction <50%) (24.0% vs 11.0%; P=.01) than those without ED. Erectile dysfunction was associated with a shorter exercise time (8.0 vs 10.1 minutes; P<.001) and lower Duke treadmill score (4.4 vs 8.4; P<.001). Multivariate analysis showed ED to be an independent predictor of severe coronary heart disease (odds ratio, 2.50; 95% confidence interval, 1.24-5.04; P = .01) and high-risk MPS findings (summed stress score >8, transient ischemic dilation, or left ventricular ejection fraction <35%) (odds ratio, 2.86; 95% confidence interval, 1.43-5.74; P = .003). CONCLUSIONS: Erectile dysfunction is common in men referred for MPS, is associated with markers of adverse cardiovascular prognosis, and is an independent predictor of severe coronary heart disease and high-risk MPS findings. These results suggest that questioning about sexual function may be a useful tool for stratifying risk in individuals with suspected coronary heart disease.

Imaging techniques in cardiac electrophysiology.

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient's cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient's anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.

Admission predictors of in-hospital mortality and subsequent long-term outcome in survivors of ventricular fibrillation out-of-hospital cardiac arrest: a population-based study.

BACKGROUND: Survival following out-of-hospital cardiac arrest (OHCA) from ventricular fibrillation (VF) is poor and dependent on a rapid emergency response system. Improvements in emergent early response have resulted in a higher percentage of patients surviving to admission. However, the admission variables that predict both short- and long-term survival in a region with high discharge survival following OHCA require further study in order to identify survivors at subsequent highest risk. METHODS: All patients with OHCA arrest in Olmsted County Minnesota between 1990 and 2000 who received defibrillation of VF by emergency services were included in the population-based study. Baseline patient admission characteristics in survivor and nonsurvivor groups were compared. Survivors to hospital discharge were prospectively followed to determine long-term survival. RESULTS: Two hundred patients suffered a VF arrest. Of these patients, 145 (73%) survived to hospital admission (7 died within the emergency department) and 79 (40%) were subsequently discharged. Sixty-six (83%) were male, with an average age of 61.9 +/- 15.9 years. Univariate predictors of in-hospital mortality included call-to-shock time (6.6 vs. 5.5 min, p = 0.002), a nonwitnessed arrest (75.4 vs. 92.4%, p = 0.008), in-field use of epinephrine (27.8 vs. 93.4%, p < 0.001), age (68.1 vs. 61.9 years, p = 0.017), hypertension (36.1 vs. 14.1%, p = 0.005), ejection fraction (32.4 vs. 42.4, p = 0.012), and use of digoxin (34.9 vs. 12.7%, p = 0.002). Of all these variables, hypertension [hazard ratio (HR) 4.0, 95% CI 1.1-14.1, p = 0.03], digoxin use (HR 4.5, 95% CI 1.3-15.6, p = 0.02), and epinephrine requirement (HR 62.0, 95% CI 15.1-254.8, p < 0.001) were multivariate predictors of in-hospital mortality. Nineteen patients (24%) had died prior to the survey follow-up. Five patients experienced a cardiac death, resulting in a 5-year expected cardiac survival of 92%. Multivariate variables predictive of long-term mortality include digoxin use (HR 3.02, 95% CI 1.80-5.06, p < 0.001), hypertension (HR 2.06, 95% CI 2.12-3.45, p = 0.006), and call-to-shock time (HR 1.18, 95% CI 1.01-1.38, p = 0.038). CONCLUSION: A combined police/fire/EMS defibrillation program has resulted in an increase of patients surviving to hospital admission after OHCA. This study confirms the need to decrease call-to-shock times, which influence both in-hospital and long-term mortality. This study also identifies the novel demographic variables of digoxin and hypertension, which were also independent risk factors of increased in-hospital and long-term mortality. Identification of these variables may provide utility in identifying those at high-risk of subsequent mortality after resuscitation.