QRS duration predicts death and hospitalization among patients with atrial fibrillation irrespective of heart failure: evidence from the AFFIRM study.

AIMS: The association of QRS duration (QRSd) with morbidity and mortality is understudied in patients with atrial fibrillation (AF). We sought to assess any association of prolonged QRS with increased risk of death or hospitalization among patients with AF. METHODS AND RESULTS: QRS duration was retrieved from the baseline electrocardiograms of patients enroled in the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study and divided into three categories: <90, 90-119, ≥120 ms. Cox models were applied relating the hazards of mortality and hospitalizations to QRSd. Among 3804 patients with AF, 593 died and 2305 were hospitalized. Compared with those with QRS < 90 ms, patients with QRS ≥ 120 ms, had an increased mortality [hazard ratio (HR) 1.61, 95% confidence interval (CI): 1.29-2.03, P < 0.001] and hospitalizations (HR 1.14, 95% CI: 1.07-1.34, P = 0.043) over an average follow-up of 3.5 years. Importantly, for patients with QRS 90-119 ms, mortality and hospitalization were also increased (HR 1.31, P = 0.005 and 1.11, P = 0.026, respectively). In subgroup analysis based on heart failure (HF) status (previously documented or ejection fraction <40%), mortality was increased for QRS ≥ 120 ms patients with (HR 1.87, P < 0.001) and without HF (HR 1.63, P = 0.02). In the QRS 90-119 ms group, mortality was increased (HR 1.38, P = 0.03) for those with HF, but not significantly among those without HF (HR 1.23, P = 0.14). CONCLUSION: Among patients with AF, QRSd ≥ 120 ms was associated with a substantially increased risk for mortality (all-cause, cardiovascular, and arrhythmic) and hospitalization. Interestingly, an increased mortality was also observed among those with QRS 90-119 ms and concomitant HF.

Adenosine testing in atrial flutter ablation: unmasking of dormant conduction across the cavotricuspid isthmus and risk of recurrence.

BACKGROUND: Adenosine-induced hyperpolarization may identify pulmonary veins at risk of reconnection following electrical isolation for atrial fibrillation. The potential role of adenosine testing in other arrhythmic substrates, such as cavotricuspid isthmus (CTI)-dependent atrial flutter, remains unclear. We assessed whether dormant conduction across the CTI may be revealed by adenosine after ablation-induced bidirectional block, and its association with recurrent flutter. METHODS AND RESULTS: Patients undergoing catheter ablation for CTI-dependent flutter were prospectively studied. After confirming bidirectional block across the CTI by standard pacing maneuvers, adenosine (≥ 12 mg IV) was administered to assess resumption of conduction, followed by isoproterenol (ISP) bolus. Further CTI ablation was performed for persistent (but not transient) resumption of conduction. Bidirectional block across the CTI was achieved in all 81 patients (63 males), age 61.2 ± 11.0 years. The trans-CTI time increased from 71.9 ± 18.1 milliseconds preablation to 166.2 ± 26.4 milliseconds postablation. Adenosine elicited resumption of conduction across the CTI in 7 patients (8.6%), 2 of whom had transient recovery. No additional patient with dormant conduction was identified by ISP. Over a follow-up of 11.8 ± 8.0 months, atrial flutter recurred in 4 (4.9%) patients, 3/7(42.9%) with a positive adenosine challenge versus 1/74 (1.3%) with a negative response, P = 0.0016 (relative risk 31.7). CONCLUSION: Adenosine challenge following atrial flutter ablation provoked transient or persistent resumption of conduction across the CTI in almost 9% of patients and identified a subgroup at higher risk of flutter recurrence. It remains to be determined whether additional ablation guided by adenosine testing during the index procedure may further improve procedural outcomes.