Clinical impact of nonsustained ventricular tachycardia recorded by the implantable cardioverter-defibrillator in patients with hypertrophic cardiomyopathy.

Nonsustained ventricular tachycardia (NSVT) is a risk factor for sudden death (SD) in hypertrophic cardiomyopathy (HCM). Implantable cardioverter-defibrillators (ICDs) enable accurate assessment of NSVT burden and characteristics. In a cohort of HCM patients with ICD, we characterized Holter- and ICD-retrieved NSVT and evaluated their relationship with prognosis. We studied a cohort of consecutive HCM patients who underwent Holter ECG before receiving a primary prevention ICD. Patients were followed from ICD implantation to the first appropriate ICD therapy. We evaluated the association of NSVT characteristics with ICD interventions. Study cohort included 51 HCM patients (28 males, mean age: 48 ± 15 years). Thirty-four patients (66%) had NSVT at pre-ICD Holter ECG. Out of 17 patients with negative baseline Holter, 7 (41%) showed ICD-NSVT. In patients with both Holter- and ICD-NSVT, these latter were faster (199 ± 27 bpm vs. 146 ± 24 bpm; P < 0.001) and longer (16 ± 8 beats vs. 10 ± 11 beats; P = 0.008) than Holter-NSVT. During follow-up (38 ± 24 months), 11 patients (22%) experienced appropriate ICD therapy. NSVT length in beats (hazard ratio [HR]: 1.05; 95% CI: 1.00-1.10; P = 0.02) but not heart rate (HR: 1.00; 95% CI: 0.98-1.02; P = 0.86) predicted ICD intervention. A simple index of NSVT severity (heart rate × length in beats/100 >28) predicted ICD intervention (HR: 5.45; 95% CI: 1.10-27.32; P = 0.03). Long-lasting and rapid NSVT recorded during continuous rhythm monitoring predict appropriate ICD intervention in high-risk HCM patients. Further studies should assess whether prolonged rhythm monitoring may assist in evaluating patients at intermediate risk of SD, in which the decision to implant an ICD needs to be individualized.

Francia P ，Santini D ，Musumeci B ，Semprini L ，Adduci C ，Pagannone E ，Proietti G ，Volpe M ，Autore C ... -  《-》

Rapid Device-Detected Nonsustained Ventricular Tachycardia in the Risk Stratification of Hypertrophic Cardiomyopathy.

Nonsustained ventricular tachycardia (NSVT) detected by ambulatory Holter (Holter NSVT) is a major risk factor for sudden cardiac death in hypertrophic cardiomyopathy (HCM). We hypothesized that the prognostic utility of Holter NSVT in HCM would improve with prolonged monitoring and a higher heart rate cut-off for detection. We enrolled 60 patients (44 ± 14 years) with HCM, who had a prophylactic implantable cardioverter defibrillator (ICD). Positive Holter NSVT (prior to implant) was defined as ≥3 beats at ≥120 beats per minute (bpm). We assessed the prevalence of rapid NSVT (RNSVT) detected by their ICD within 12 months of its implant, defined as 4-16 beats at ≥150-200 bpm. The primary outcome was appropriate ICD therapy (antitachycardia pacing and shocks) for sustained ventricular arrhythmia (VA). Holter NSVT was detected in 34 patients. RNSVT occurred in 21 (35%) patients of whom five did not have Holter NSVT. Over a median follow-up of 61 (interquartile range 29, 129) months after ICD implant, nine patients had VA. RNSVT, but not Holter NSVT, was significantly associated with VA (hazard ratio 6.2, 95% confidence interval [1.3-30], P = 0.01) by multivariable Cox regression analysis that included conventional risk factors. Receiver operating characteristic analysis for RNSVT (area under curve 0.80, P = 0.005) showed that the occurrence of ≥2 episodes of RNSVT discriminated patients for VA optimally (sensitivity 78%, specificity 84%, positive predictive value 47%, negative predictive value 96%). In this pilot study, RNSVT detected by continuous monitoring independently predicted VA in HCM and offered superior discrimination of VA risk compared to conventional risk factors, including Holter NSVT. Future studies are needed to validate these findings in a larger, unselected HCM cohort.

Viswanathan K ，Suszko AM ，DAS M ，Jackson N ，Gollob M ，Cameron D ，Spears D ，Woo A ，Rakowski H ，Khurana M ，Chauhan VS ... -  《-》

Prognostic Implications of Nonsustained Ventricular Tachycardia in High-Risk Patients With Hypertrophic Cardiomyopathy.

The prognostic significance of nonsustained ventricular tachycardia (NSVT) in patients with hypertrophic cardiomyopathy is incompletely resolved. The study group comprised 160 patients with implantable cardioverter defibrillators (ICDs), of whom 94 patients had 24- to 48-hour ambulatory monitoring preimplant. ICDs were interrogated and ambulatory ECGs monitored for NSVT episodes, with associations between NSVT- and ICD-treated ventricular arrhythmias examined. Eighty-six (54%) patients had runs of NSVT, including 17 before implant on ambulatory monitoring, 44 after ICD implantation, and 22 on both. Agreement between preimplant ambulatory monitoring and ICD interrogation for detecting NSVT was poor (κ=0.18). Eighteen of 86 patients (21%) with NSVT and 6 of 74 patients (8%) without NSVT experienced ICD-treated ventricular tachycardia (VT)/ventricular fibrillation (VF). NSVT was significantly associated with ICD-treated VT/VF (adjusted hazard ratio, 3.98; 95% confidence interval, 1.41-11.29; P=0.0093). ICD-treated VT/VF was associated with NSVT runs at a rate >200 beats per minute (adjusted hazard ratio, 15.63; 95% confidence interval, 4.01-60.89; P<0.0001) and >7 beats (adjusted hazard ratio, 6.26; 95% confidence interval, 2.02-19.41; P=0.0015). Repetitive runs of NSVT were also associated with ICD-treated VT/VF (adjusted hazard ratio, 9.22; 95% confidence interval, 2.53-33.60; P=0.0008). Slower (≤200 beats per minute), shorter (≤7), or a single run of NSVT were not associated with ICD-treated ventricular arrhythmias. On extended monitoring, NSVT was independently associated with ICD-treated ventricular arrhythmias, supporting the importance of NSVT in hypertrophic cardiomyopathy risk stratification. Faster rate (>200 beats per minutes), longer (>7 beats), and repetitive runs of NSVT were more highly predictive of ICD-treated VT/VF.

Wang W ，Lian Z ，Rowin EJ ，Maron BJ ，Maron MS ，Link MS ... -  《-》

Left intraventricular pressure gradient in hypertrophic cardiomyopathy patients receiving implantable cardioverter-defibrillators for primary prevention.

Yazaki K ，Suzuki A ，Shiga T ，Minami Y ，Arai K ，Ashihara K ，Shoda M ，Hagiwara N ... -  《BMC Cardiovascular Disorders》

Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy.

Maron BJ ，Spirito P ，Shen WK ，Haas TS ，Formisano F ，Link MS ，Epstein AE ，Almquist AK ，Daubert JP ，Lawrenz T ，Boriani G ，Estes NA 3rd ，Favale S ，Piccininno M ，Winters SL ，Santini M ，Betocchi S ，Arribas F ，Sherrid MV ，Buja G ，Semsarian C ，Bruzzi P ... -  《-》