Left atrial functional changes following short-term exercise training.

BACKGROUND: Exercise-induced adaptations of the human atria remain understudied, particularly early in the training process. We examined the effects of short-term high-intensity interval training (HIT) and continuous moderate-intensity training (CMT) on left atrial (LA) systolic and diastolic function, relative to left ventricular (LV) function in young, healthy men, by speckle tracking echocardiography (STE). METHODS: Fourteen untrained men (mean age = 25 ± 4 years) were randomized to HIT or CMT, and assessed before and after six training sessions over a 12-day period. HIT included 8-12 intervals of cycling for 60 s at 95-100% of maximal aerobic power (VO2MAX), interspersed by 75 s of cycling at 10 % VO2MAX. CMT consisted of 90-120 min of cycling at 65% VO2MAX. RESULTS: VO2MAX increased following HIT and CMT by 11.5 and 5.5%, respectively (p < 0.05). Calculated plasma volume expanded 11 % following HIT and 10% following CMT (p < 0.005). Resting LV volumes and ejection fraction were unaltered following training. Peak atrial longitudinal strain increased following HIT (41.8 ± 5.2%-47.1 ± 3.7%, p < 0.01) and CMT (38.5 ± 4.6%-41.7 ± 6.0%, p < 0.01). Atrial systolic strain rate increased following HIT (1.6 ± 0.2%/s-2.0 ± 0.3%/s, p < 0.01) and CMT (1.6 ± 0.2%/s-1.9 ± 0.2%/s, p < 0.01). CONCLUSIONS: LA function assessed by STE improves rapidly during short-term intensive exercise training.

Are measures of left ventricular systolic performance during low dose dobutamine stress echocardiograms repeatable over time?

To establish the test-retest reliability and the normal dose-response relationship of echocardiographic measures of Left Ventricular (LV) contractile function to low dose dobutamine stress in healthy individuals. Thirty healthy volunteers (23 males, 7 females) with an average age of 38 ± 13 years underwent dobutamine stress echocardiography (DSE) (at successive doses of 0, 5, 10, and 20 mcg/kg/min) on two occasions, separated by 14 days. Ejection fraction (EF) was determined from 2D echocardiographic measures of left ventricular (LV) end diastolic and end systolic volumes. Longitudinal strain (S) and strain rate (SR) were measured using 2D speckle tracking analysis from three consecutive cardiac cycles. The Intraclass Correlation Coefficient (ICC) and the Coefficient of Variation (CV) were calculated to assess reliability and variability of the study population's EF, S, and SR responses to increasing doses of dobutamine. Left ventricular S and EF gradually increased with low doses of dobutamine but reached a plateau between 10 and 20 mcg/kg/min. Strain rate, however, gradually increases with each increasing dose of dobutamine. These responses were replicated on Day 2 with a high degree of reliability as determined from the ICC and low variability as determined from the CV, which fell within acceptable limits (<10 %). Left ventricular EF, S and SR can be measured during DSE with a high degree of test-retest reliability, and may be of clinical value when serial follow up of DSE measures of LV performance is indicated over time.

A "no-option" left main PCI registry: outcomes and predictors of in hospital mortality-utility of the logistic EuroSCORE.

BACKGROUND: Although high-risk left main PCI populations have been previously described, there is little data describing outcomes and the role of the logistic EuroSCORE in surgical turndown cohorts or patients in extremis due to acute infarction or cardiogenic shock from left main ischemia. METHODS: Consecutive patients with unprotected LM PCI who were surgical turndowns or in extremis were included in this retrospective cohort from 2004 to 2009 at two tertiary centers. Predictors of in-hospital mortality were identified utilizing routine and stepwise logistic regression. RESULTS: There were a total of 56 patients with mean age of 69 (±13). There were 23 (41%) patients with cardiogenic shock. The mean logistic EuroSCORE was 23.5% ± 21%. In-hospital death occurred in 12 (21%) patients, largely restricted to the shock subgroup (11/12). Univariate predictors of mortality included peak CK levels (P = 0.01), transfusion (P = 0.01), cardiogenic shock (P < 0.002), male gender (P = 0.027), and logistic EuroSCORE (P = 0.01). Stepwise logistic regression yielded logistic EuroSCORE (P = 0.04, OR: 1.25 (95% CI: 1.01-1.56) for every 5% increase) and peak CK level (P = 0.001, OR: 1.23 (95% CI: 1.09-1.40) for every 500 unit increase) as independent predictors of in-hospital mortality. The AUC ROC for logistic EuroSCORE was 0.73; and for logistic EuroSCORE plus peak CK level was 0.89. CONCLUSION: PCI appears to be a reasonable option in the high risk "no option" LM population, with the logistic EuroSCORE and peak CK levels being independent predictors of in-hospital mortality. Specifically, the logistic EuroSCORE and peak CK level combined discriminate in-hospital mortality with a high degree of certainty.

The acutely occluded left main coronary artery culprit in cardiogenic shock and initial percutaneous coronary intervention: a substudy of the Manitoba "no option" left main PCI registry.

We aim to describe the in-hospital outcomes of the first reported Canadian cohort of patients with cardiogenic shock and acute myocardial infarction (MI) due to acute and total occlusion of the left main coronary artery, treated with initial percutaneous coronary intervention (PCI). Acute left main thromboses with cardiogenic shock were identified (N = 8) from a retrospective consecutive cohort of high risk left main PCI (N = 56) performed at our institution from 2004-2009. The mean age was 62.3 ± 13.2 years, with 6 (75%) male patients. Successful PCI was performed in all patients, with thrombectomy utilized in 4 patients (50%), stenting in 7 patients (88%), and intra-aortic balloon pump augmentation in 7 patients (88%). Two patients (25%) required extracorporeal membrane oxygenation (ECMO) and 2 other patients required ventricular assist devices. Post-PCI coronary artery bypass grafting (CABG) was performed for 2 patients (25%). The mean SYNTAX score was 26.6 ± 10.5. The mean logistic EuroSCORE was 30.4 ± 12.6%. In-hospital mortality occurred in 3 patients (38%). Acute left main occlusion is a rare but devastating presentation of myocardial infarction, invariably with cardiogenic shock. Emergent PCI may be an effective method to acutely revascularize this subset of patients; however, aggressive post-PCI care including ECMO, CABG, and ventricular support may be required to improve patient survival.

Obstructive sleep apnea: effects of continuous positive airway pressure on cardiac remodeling as assessed by cardiac biomarkers, echocardiography, and cardiac MRI.

BACKGROUND: Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular morbidity and mortality. Although previous echocardiographic studies have demonstrated short-term improvement in cardiovascular remodeling in patients with OSA receiving continuous positive airway pressure (CPAP) therapy, a long-term study incorporating cardiac biomarkers, echocardiography, and cardiac MRI (CMR) has not been performed to date. METHODS: A prospective study of 47 patients with OSA was performed between 2007 and 2010. Cardiac biomarkers, including C-reactive protein (CRP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and troponin T (TnT), were measured at baseline and serially over 1 year. All patients underwent baseline and serial transthoracic echocardiography (TTE) and CMR to assess cardiac remodeling. RESULTS: Following 12 months of CPAP therapy, levels of CRP, NT-proBNP, and TnT did not change significantly from normal baseline values. As early as 3 months after initiation of CPAP, TTE revealed an improvement in right ventricular end-diastolic diameter, left atrial volume index, right atrial volume index, and degree of pulmonary hypertension, which continued to improve over 1 year of follow-up. Finally, left ventricular mass, as determined by CMR, decreased from 159 ± 12 g/m(2) to 141 ± 8 g/m(2) as early as 6 months into CPAP therapy and continued to improve until completion of the study at 1 year. CONCLUSION: Both systolic and diastolic abnormalities in patients with OSA can be reversed as early as 3 months into CPAP therapy, with progressive improvement in cardiovascular remodeling over 1 year as assessed by both TTE and CMR.

Sudden pacemaker failure.

Two cases of sudden pacemaker failure due to fractured wires supplying power to the generator are described. Both devices were Kappa KD703 (Medtronic Inc., Minneapolis, MN, USA) implanted in a prepectoral subcutaneous pocket. In 2002, Medtronic issued an advisory regarding Kappa 700/600 devices. A number of these devices, all subpectoral implants, had presented with intermittent or no output due to fractured wires supplying power to the devices, leading to recommendations to replace susceptible devices in pacemaker-dependent patients. These two cases may warrant extension of this advisory to include all these devices, regardless of implant location.